What’s the problem with charging by superheat, it worked for me for the last 43 years, TXV, PISTON, or CAP tube, cuts no ice, besides any installer worth his salt will put a sight glass after the dryer if it’s a TXV system ! Anyways I can judge operating conditions with my hand on the suction line, I don’t need a temperature probe unless i’m diagnosing a problem. Forget subcool just make sure of your gauge readings, and look for telltale problems that needle will show by its movements, like a pulsation that may indicate a sticking discharge valve, oh i’m sorry I see you have one of them modern digital manifolds that won’t show things like that, oh well maybe it’s also a radio to keep you entertained while your working. Also your liquid line should be warm to the touch, NOT HOT, and NOT COLD, one could indicate a dirty condenser, the other a plugged system and be careful, Carrier likes to sandwich two coils together on some of their units and they get dirty in between where you cannot see ! Never cared much for Carrier and I can’t stand Trane.
There are a number of ways you can fail by using superheat only. Subcool is used on TXV controlled units to insure there is sufficient refrigerant to feed under all load conditions. Placing a sight glass on a modern A/C unit controlled by a TXV will not give an accurate charge. We are far beyond that. It is kind of 1970s tech. An A/C unit with several cap tubes, superheat can be normal with one tube blocked. An incorrect piston can also give you incorrect superheat. Air in the system will also give an abnormally high head that will increase flow in fixed orifice systems and lower superheat. Low airflow across the evap will also give you correct superheat on a system with low efficiency. Gauge readings must also be checked. There are more, but this will do for now. I would suggest that the hand on the suction line be supplemented by correct gauge readings, temp probe on the liquid line, probe on the suction line, a check with manufacturer's instruction (located on the model plate), ambient temp probe to determine if the gauge readings match, temp split across the evap. I used this method on all systems I worked on. It takes little time to set these probes and they will save you from mistakes. GFM
grayfurnaceman I edited my comment, I assumed monitoring your gauges was a given, you will see that everything you said in your comment is addressed. Any of the problems you presented will show up if the technique I presented is followed, now diagnosing that problem will depend on your technical abilities. And about your sight glass comment, a sight glass is the only fool proof method of insuring a solid column of liquid to your expansion valve, I don’t care what they taught you ! And I find that 70s technology comment pretty funny, I didn’t realize the laws of thermodynamics have been changed ! Want to talk about something, let’s talk about the modern engineering marvels I have been running into lately, like using flammable gasses for refrigerant, i’ll bet you even think the insane pressures of R410A is going to work out, just make sure you honor the 5 year warranty on these compressors in the units your installing as they start blowing out left and right every time the mercury cracks the upper 90s.
Question about a R410A systems, when the system’s compressor won’t energize due to low refrigerant with the low pressure switch, and you have a few lbs remaining in the system, can you charge as liquid directly to high side with compressor off? That is, weighing it in until system won’t accept any more, then, topping it off via subcooling method via low line. Or, must system always be in a total vacuumed state before you can ever do so? Moreover, in what situations can add via high line as liquid.
Unless the charging cylinder is at a much higher temp than the A/C unit, it will not move. I would not consider it viable. The only viable method of liquid in the high side, is with the system well below saturated or, of course, evacuated. GFM
@@userjim9 I have never been a fan of warming blankets. Jamming the contactor or bypassing the low pressure switch is viable, but short cycling will not change the inability to charge in the high side. GFM
Paul.... If a R410 unit is low when testing on a service call or check up, that means the R410 is unbalanced with concerns to oil mixture. R410 requires the precise mixture for it to cool properly and oil sufficiently. Only if the unit is brand new and just requires a top up then can you just add. Otherwise the system (by manufacturer specs) requires you to recover and start from 0 if the unit is found to be low
Just like I learned in school... Although there wasn't any creation called R410a back then. We had it easy with r22, blended refrigerants are a pain... Lol. Good video as always Gray. Thanks for all the knowledge you pass along to all of us.
I didnt notice any recovery machine, i hope you didnt do any atmospheric recovery. just messing with you, good video. id like to add anytime i get into a system that is low, i will leak check first, and i always change out the schrader cores on all ports that have them. as well as clean all coils and change air filters first before taking any readings. I just dont like having call backs
You are The First mechanic among all the Super Techs on you tube that stated the obvious=Back to square one=clean coils,air filters leak test and repair. Good on you mate. Just my two bob worth : R-22 systems can be toped up as for R-22 is not a blend. R-410 and other blended refrigerants should be dumped and recharged with virgin stock. Change filter/dryer. Greetings from Australia.
If only all the customers would pay for the right job to be done too many moron techs give them too many options and taint their minds it should be stamped and said this is proper code and has to be done like this
Sir ....ur the man.... i wish there was utube when i was in school or better yet u were the teacher...i learn alot from ur videos....thank you so much ...really appreaciated!!!!
Another superb run-through for how to adjust charge in an R410A split system with a TXV. I’m finalizing the charge in a similar system right now. It has a brand new condensing unit, but I am still using the existing evaporator and line set. So I knew additional R410A would need to be added to the pre-charged amount which was already in the new condensing unit. It required about 3 LB to be added. I think I’m getting close to the right amount now, but will make one more test of subcooling, indoor supply vs. return air temperature split, and superheat exactly like what is shown here in this video.
I have one of those SMAN4 gauges along with the wireless sensors and transmitters. No need for any math, once set up, it reads the superheat and subcooling in real time. This allows me to very quickly zero in the correct charge and squeeze out the highest efficiency the unit is capable of.
I personally, have a lot of problems in charging system with the TXV & Receiver. I think this give me a lot more clear than before, but if you have more example of charging, please post it. I am so grateful that you are sharing your experiences. John
I did residential for 7 years, I'm currently working for the last 7 1/2 years in big commercial equipment. I started looking for any videos HVAC because I always believe that in this trade is always something new to learn and I found one of your videos and I was hooked. I wish I would it have an instructor like you when I first started in this trade, thank you sir!
I have the same problem . Over thirty years working on systems that hold 50,000 lbs of charge to half an once . Something is always done with a different method to the madness
Hey mate, I saw another video of a guy adjusting the superheat (on a walk in cool room) by adjusting the TXV. This is incorrect right? The only way to do it is what you have done in this video by adding refrigerant to get the correct sub cooling..? Also I always thought it was bad juju to charge a system with liquid or is it ago to do it by adding slowly?
I seldom adjusted TXVs. It would be among the last things I would do when encountering high superheat. Charge levels are best determined by subcool. Blend refrigerants must be charged as a liquid. Liquid charging can be done either high side with unit empty or low side by metering the refrigerant to avoid liquid slugging of compressor. Hope this helps. GFM
Isn't the 11 degrees of subcool rated for a 95 degree outdoor temp? And for 410-A, a good suction pressure is around 120 and a good head pressure is around 420 (also rated for a 95 degree outdoor temp). Shouldn't you drive the head pressure up to around 420 to simulate what the manufacturer recommends? 11 degrees of subcool at 84 degrees outside won't be the same on a hotter day.
According to Trane, the sub cool should stay the same at all temps except below 55F outdoor ambient. It does seem that the sub cool would drop with higher ambients because of the additional boiling refrigerant, but it does not seem to be true. However, I will test it at higher temps and do a video on it. As for the suction pressure, If the system is designed and working properly, the suction pressure will correspond to the indoor air temp and wet bulb. As far as I know, no manufacturer recommends simulating 95F for checking charge. GFM
I'm still a fairly new tech (3 yrs. exp) and still learning the more specific technical details for individual units and systems. I would like to ask, when the information is not present on the unit,for example, older unit with faded tags or new one with missing paperwork. How do you go about finding out the exact specifications for what the unit should run at,as far as subcooling/fan cfm/or static air pressure? Thank you for your time and good video.
Ah, the age old question. Throw in mismatched outdoor unit and evap, and it really gets tough. Target superheat can be used if it is a fixed orifice. TXVs are really pretty simple. You probably will not go wrong 11 to 13 subcool. Fan cfm can be handled by delta T across the coil and evap temp. If the evap temp is below 40F with normal cooling ambients, cfm could be low. Static is quite variable with different systems. Hope this helps. GFM
I know this is a training video probably at your house but would it not be good to mention that if a tech gets to a R410A unit and its found to be low on refrigerant that the unit should be recovered and all new freon put back in so that the right amount of mix is in the unit?. just a thought
+grayfurnaceman What Colin G is saying is that if a tech sees that a system is low on 410a, the tech cannot know how much of R32 or R135 (the components of R410a) has leaked out, so in order to get an honest R410a in the system, the tech should recover the old refrigerant and add all fresh R10a.
That could be pretty costly if it only needs a small amount to bring up to full charge, having to dump the full charge and reinstall with new refrigerant. Can the proportion of the existing mixture be determined by checking the stabilized vapor pressure at the ambient temperature? For a proper blend of R410a, there should be a specific pressure corresponding to the ambient temperature with the system off and given a chance to stabilize. If it's off, maybe adding the lighter component to restore the blend could be done instead of adding the R410a blend. Something like making a measurement of the specific gravity of antifreeze and adjusting by adding coolant or distilled water to achieve the target specific gravity. Otherwise, is there an electronic method of reading the blend components in the system?
Great video. I do have a question. I thought if you were charging by superheat, you should attach the temp probe near the suction service valve. Thanks for the video
Excellent video probes that when u have the time and the dedicated tools the charge would be pretty close to perfect.....One must be careful about Microchannel Cond. Units that can be overcharged very easy running most times into Overcharged High Head Situations specially on 94 degrees temp summer days....tnks
You can use a liquid charging adapter when charging. A liquid charging adapter is basically a fitting that has a small orifice in it to prevent liquid slugging. A liquid charging adapter is just cheap insurance.
r410a system ( with fixed orifice) with equalized pressures of around 200psig. But once compressor starts the low side drops to 50 psig while the high side goes up to 300psig. I checked superheat was like 80F and subcooling was 2F. Does this mean the system has leaked out all the refrigerant? Does the 200psig equalized pressures means there's refrigerant in the system? thank you.
Hi, my r410a with txv unit. The suction saturation temp is about 33F and suction line temp is 48F giving 15F of superheat. But why is my liquid line saturation temp is 97 and my liquid line temp is also 97. I tried adding some refrigerant but nothing changes. This is a high velocity system air handler with a slab coil. I think my suction saturation temp is also too low. Both coils are clean and txv valve is new. Any help would be greatly appreciated. Thanks
You must charge liquid thru high side in an evacuated system. If you charge thru low side, you will put liquid into the compressor and it may slug when started. GFM
Paul.... If a R410 unit is low when testing on a service call or check up, that means the R410 is unbalanced with concerns to oil mixture. R410 requires the precise mixture for it to cool properly and oil sufficiently. Only if the unit is brand new and just requires a top up then can you just add. Otherwise the system (by manufacturer specs) requires you to recover and start from 0 if the unit is found to be low
410 is a 3 way blend. Charge one system via gas and you diminish the quality of the rest of the bottle proportionately to the number of times its done like that.
Question: So on my new Ruud 3.5 ton AC with "N" coil, using 34 ft of (3/8 liquid & 7/8 vapor) lineset. I know to add .6oz per foot over 15 ft. but was curious if it was necessary to add extra 410a to account for the copper elbows? I have three 7/8" elbows and then 2 long hand bends for the 3/8". Cant determine if they are telling me I need to do this no matter what or just if I have a long lineset and high vertical rise which I do not have. Lineset goes 8 feet up from AC service valves to ceiling then 22 feet straight to furnace room and then 3 feet down with the 2 elbows to connect to coil. Manual states, All units are factory charged with R-410A refrigerant to cover 15 feet of standard size interconnecting liquid and vapor lines with a required field installed filter drier. I have installed the filter drier inside before coil and coil also has TXV installed with bulb of course at 10 o'clock position on vapor line also on outside of cabinet.
You said you were gonna do a video on recharging-subcool-superheat ect, and you kept your promesse. Thank you so much. It changed few things in the way I was doing it like taking the low pressure temp after the evaporator for superheat.instead of outside. If ever you have some trick to solve slow leak, you would make my day. Thank you
Good video as always, but I wish you would show where your probes are placed for your various measurements. As it is, some parts are confusing without that context. It would also help to mention alternative ways to get the saturation values without a digital gauge set.
Too confusing for beginners. He keeps moving back and forth to different temp readings with no indication as to what the heck the temp is measuring. Which temp probe is connected to which line? And, why is it important to know the ambient temp when you're doing subcooling? And, he keeps moving back and forth to various readings, just reading off numbers. so fast that it makes your head spin. Terribly confusing video for newbies.
Paul.... If a R410 unit is low when testing on a service call or check up, that means the R410 is unbalanced with concerns to oil mixture. R410 requires the precise mixture for it to cool properly and oil sufficiently. Only if the unit is brand new and just requires a top up then can you just add. Otherwise the system (by manufacturer specs) requires you to recover and start from 0 if the unit is found to be low
+Colin G When a blend has a leak in the liquid side, the refrigerant will leak the highest pressure refrigerant at a higher rate than the lower pressure one. R-410A is a blend of R-32 (50%) and R-125 (50%). It is called a near Azeotropic blend. Meaning it almost leaks at the same rate for both refrigerants. At approx 70F R-125 boils at -55F. At the same temp, R-32 boils at -61F. Looking at the different boiling temps there is only 6F difference. Remember, both refrigerants are leaking, with the higher pressure one leaking slightly more. With these numbers in mind, a small leak can be topped off (after the leak is repaired) with refrigerant without changing out all the refrigerant. Certainly, if there was a large leak, the refrigerant should be replaced. I have never seen a manufacturer claim that a small leak must have the refrigerant replaced. If you have other specs, I would like to see them. Thanks for the thoughts. GFM
Very good video . I have Question pls If he charge with sub cooling when there is a TXV and by wet b dry b on the super heat with non TXV . In what category fits units with capillary metering device. And one more q. If I was to do sub-cooling calculation on a R410a split in cooling mode do I doit in test mode ? Full fan run speed? 18 Celsius set temperature? Thank you
+lucly nn The capillary device is also considered a fixed orifice device and is charged by superheat with wet build and dry bulb or target superheat. GFM
Good video. I appreciate your candidness about recover and refill vs. top off. It is first I have seen with that viewpoint. As a DIY guy, this means I just need a decent manifold set, a scale, temp probe(s), and jug of 410a. I will leave the other tools to the professional when it is time to have serious repairs performed. My unit has been serviced 2 times, 2 diff techs. Neither one found a leak, both ended up charging it up and that was it. Strange observation on my part - it appears to leak when it is powered off for an extended period of time. Crazy.
Love that manifold …..did some refrigeration many moons ago . We didn’t have that , had to do all the superheat and sub cooling by math , wonder how much it cost …thanks a lot for the video ! You explained and a few minutes what it used to take weeks to grasp
Some posts are questioning if the system is low on refrigerant that you need to recover and start with Fresh . how serious is this ? you added 3.3 lbs that sounds like alot My 3yr old system has a leak and 3.2 ls was added . should I turn off unit until they find leak and recover and recharge with fresh R410 A ?
Whether to recharge with new is dependent on several factors. TXV controlled units are pretty easy. Charge until subcool is right. Fixed orifice is a little harder. Sometimes remove and recharge is the best way. You can also use target superheat without removing the charge. This is assuming the system can be pumped down for leak repair. GFM
Thanks Can you describe the several factors ? Why does the ease of charge have anything to do with the R410 being reused . I have heard the mixture proportion is critical and just topping isnt an accurate blend. if large quantity is added . is that true ? 3.2 sounds like a large % of an 8.8 full system . Tech said he can pump all refrigerant back to od unit then replace evap coil if leak is there . I still have questions of proper mix volume when adding 3.2 lbs . Still I dont want to pay for 8.8 virgin A410A if not necessary Please advise .
Mixture proportion is critical. However, R-410A has 2 components whose pressure difference is only about 3#. This means you would have to lose most of the charge before any effect could be noticed. GFM
0n my 8.8 (tag stated) lb. system, we had to top up 3.2lbs to reach subcool of 8. Tech .stopped at 8 deg subcool and unit ideal is 10 +,- 3. . I guess additional could have been added to hit 10 sub on the mark . I heard HoneyWell did a test at 50 % loss and top up numerous times and no negatives to system were found .Looks like even with my line set of 30ft and evap capacity my compressor is safe . Now to find that leak . BTW 2 yrs ago the OD unit froze up ( winter) and shut down due to defrostboard failure 2 or 3 times . Is it likely the high pressure caused a leak in the OD unit ? Tech wants to pull all R410 into OD and test lineset and evap first . Wouldnt checking OD firstt be more practicle ? We havnt seen any oil or discolor anywhere as yet .Sorry so long but I do apprieciate your knowledge and experience .
i read about "target" subcool and confuses me, and i read about return wet bulb temp has to be considered on the equation also, can you make a video on that?
I am fresh out of School green horn. I very much like these videos has reminders and when I get stuck not rembering exactly what to do. Practice and "learning opportunities".. thanks again for very straightforward information.
quimshtgclg With air conditioning systems, unless manufacturer instructions are different, 15 DEGREES F of superheat is about the highest. If charge is low, superheat will increase as there is not enough charge to maintain superheat. Hope this helps.GFM
Thank you very much for your teaching I’ve been learning allot from your videos, I feel that I’m better technically,God bless you for your teaching thanks again for taking your time to make this videos
Great video and good thorough explanation! So the greater the efficiency the less you add to the ambient to get total condensing saturated temp? Like in a standard unit it's ambient plus 30 so in these high efficiency units it's plus 20? With every passing year the standard is getting higher. Will that mean that eventually we will be adding less and less to the ambient? Thanks for your wisdom!
The first reaction of manufacturers to the need to increase efficiency was to increase the size of the condenser coils. This, of course, reduced head and did increase efficiency. It was also the most expensive way to increase efficiency. So, manufacturers have changed things like compressor design, TXV design and fan motor design. The actual size of condensers has again reduced and the efficiency goals have been reached. GFM
Thanks for the video. You cover a lot of great details to watch out for. I am curious what the specific advantages of a TXV are over a fixed orifice for the evaporator. It would be interesting to see a video on an r-22 superheat charge with a fixed orifice.
What do you do if your unit does not have a subcooling chart? Is there a standard? I have an ICP Heil PGAD30D1K7 and cant find a manual or subcool chart. I am getting 10 degrees with the probe and gauges. Thoughts or help is greatly appreciated and Thank You.
Wow, Thank You for taking the time to reply to my post. I checked and it has a TXV but darn if I can find a the required subcooling requirement for this unit. It does have 10 degrees sub cooling and cools well. I just want to make sure it should not be 15. Have a great weekend and again Thank You. v/r mw
+brandon milner Just got your comment. I assume you are looking at the suction pressure. Note the return is at 70F. If you had a normal 75 to 78F, the suction would be higher. GFM
when charging by sub cooling and you get the charge right, how do you look at the super heat and determine if the txv is working properly? No one ever says what your super heat reading should be. They just sat " the super heat looks good" Whats a good reading and why??? I've read to never let super heat get below 20-25.at compressor, always check line temp. at same place you are taking pressure reading. If I could get this question resolved, I would understand super hear and sub cooling much better. Counting on you furnace man.
The txv is design to maintain a superheat of 10 degrees under perfect condition. depending on the load at the evaporator that number can be between 5 and 20 degrees, if you are out of that range......there is a problem
trharesco It depends on the application. Generally, the split should be between 16 and 22F. I will be doing more videos on temp splits this summer. GFM
I got a question I'm pretty new to the Hvac field...in class we're currently doing a recovery and a vacuum and the instructor told us to buy out own gauges so we can get used to using them.....now my question in your opinion which digital manifold is good for a beginner but also good enough to have out in the field price is not really an issue.....thnks
+Carlos Chavez The Testo and the Fieldpiece are the most common choices. I really have no problem with either of these. They are quality products. I use the Fieldpiece but that is mostly because it is easier to see on the videos. GFM
+grayfurnaceman thanks for the reply I went and bought me a testo 550 and I excited to try out..thanks again I'm really understanding more about the Hvac system just by watching your videos 👍👍👍
For manufacturers whose installation manuals advise to add additional [R-410] refrigerant for indoor matchups and/or longer line set lengths will the resulting subcool value be higher than their suggested published value? I.E. if they recommend SC of 9 based on a charge of 11.7 lbs. is it possible to see, say, 14, if you add an additional 2 lbs due to the indoor coil matchup and longer line length?
Brian Fletcher most AC systems have lists supplied with the AC that tell you how much refrigirant needs to be removed or added when line length changes.
In my career in HVAC, in 35 years of repairs, I have adjusted a TXV perhaps 10 times. In at least 5 of those times, adjustment of the TXV did not help. Look for everything else first, adjust last. GFM
@@grayfurnaceman You said you recovered some refrigerant from the unit prior to testing so you already knew it was low. Good job. Chuckyoufarley made a good point.
Kyle Faubertq The Fieldpiece is very good. Mostly the competition is between Testo and Fieldpiece. The primary reason for the use of the Fieldpiece in my videos is the larger numbers for the videos. Both of these products are very good. When I get a chance, I will be doing a comparison. Hope this helps. GFM
I cant wait to get my certs in. I always wanted to do this type of work. thanks for the great video's. this is way better then the typical schools I see people going to
IMon Trust me when i say I have very little experience. I always start by checking the airflow , making sure both coils are clean and filter is clean I would think if freon levels are low, If freon levels are normal, Insufficient heat getting to Evaporator . Overcharge of freon can cause the same problem also possible restriction at the caps I'm only going for my universal test atm It looks very easy. After i pass the test i will try to get on at a local A/C company to get better experience .
Daniel Furlong good doing on checking for airflow on everything. Lack of airflow on an evaporator will give you low pressures with a low superheat and cold suction line. You gotta run the system for 10 minutes before determining a problem with your refrigerant.
Great vid Gray. Listen Gray I'm thinking of purchasing a set of digital manifold gauges like your using. Are you up to date on which unit is a good unit to purchase at this time......?
I thought your indoor and outdoor temperatures didn't matter with TXV systems. I thought that as long as it's running desired subcooling, and the superheat is no more than 12 or 13, it was good.
John Smith TXV systems are better at lower ambients, however air conditioners run at fairly narrow indoor and outdoor temps. On residential systems, outdoor below 70F and indoor below 70F the numbers cannot always be trusted.
I happen to live in Arizona, and it can get over 118 degrees here sometimes. Let's say my indoor temperature is 70, and my outdoor temperature is 130, if the system uses a piston, will I have any superheat under these conditions?
Is it possible for the outdoor temperature to get so much hotter than indoors that there might not be any superheat? If it is about 70 indoors and 130 outdoors, would that be enough to cause zero superheat?
This is just one example of the lack of ability of HVAC service Technicians to diagnose problems and fix them. My brother had a 1.5-Ton air-conditioner installed on an oil furnace that only had a quarter horsepower blower motor and they installed an evaporator coil directly on top of the furnace which resulted in it being to close to the furnace heat exchanger causing an airflow restriction. Actually in that oil furnace the quarter horsepower blower motor should only be used with heating and never less than a third horsepower motor used when there's an evaporator coil Installed in the system. the evaporator coil was always heat under loaded. Additionally, the system almost immediately begin to lose charge in the area of the evaporator coil. The first tech who came out with had an analog manifold gauge on the suction line and saw that the pressure was normal, however, the system had a TXV metering device on it and therefore you have to charge by sub cooling and of course he didn't have any way to check either the superheat temperature or the subcooling temperature; therefore he misdiagnosed the system as being okay. Over the years the same company was called in; again a total non-diagnosis was the result. Then another company was called, which I thought they might be the best company; however, he merely removed a clean return air filter; he had a set of digital manifold gauges which showed the superheat and sub cooling of the system. Subcooling was only 1°F and normally you need 8 to 10°F of subcooling on a TXV system. However, when the superheat got down to around 16°F and the thermostat expansion valve superheat target was probably 12°F; the tech said the system is overcharged and he took the manifold gauges off the system. However, the sub cooling was only a mere 2°F; he left the system still way under charged, he never searched for the leak, nor diagnosed extremely low airflow through the system indoors resulting in situation where you couldn't possibly properly charge the system. This is only one example of how the technicians here in the Southwest Wisconsin area, where I am now living, simply can't seem do anything right, it is difficult for me to believe that HVAC service work could be that bad, but I believe the number of service technicians that do their work correctly is a very low percentage. our HVAC industry is shamefully disgraceful condition…
Hello. Is there any way to calculate subcooling for INVERTER AC without having good measuring instruments ? I have 12000btu AC ( 3500 W) r410a and is not working as it should. I live in Europe and I use it for warming up my room in heating mode. After all calculations I did and after all possible error is still far from specifications. I only have low pressure from the day it was installed : 100 psi. It was 93 F outside in that day. I kept complaining about efficiency at installer and they came last days and measured again pressure, suspecting leaks. It was again 100 psi. He started recharging using gauge only and it reached arround 130-160psi then compressor stopped. He removed refrigerant until compressor is on and that's it. When he left he measured arround 115-120 psi low side and 460psi high side. This unit has only one port for gauge measuring and high side was measured on heating mode when pressure was high. This technician doesn't have other instruments for measuring this unit except pressure gauges. Unit is working a little better now. There are higher temperature at inside unit. It was about 115 F before and now it gets 122F but there is a major change in time it gets to that temperature : it takes much longer. Before , at lower pressure it didn't passed 115F but it was fast. Now it gets after double time at 122F. Room temperature is arround 77F, outside temperature is 53F. Is it working good enough ? Can I measure suction temperature near outdoor unit and find out subcool ?
What’s the problem with charging by superheat, it worked for me for the last 43 years, TXV, PISTON, or CAP tube, cuts no ice, besides any installer worth his salt will put a sight glass after the dryer if it’s a TXV system ! Anyways I can judge operating conditions with my hand on the suction line, I don’t need a temperature probe unless i’m diagnosing a problem. Forget subcool just make sure of your gauge readings, and look for telltale problems that needle will show by its movements, like a pulsation that may indicate a sticking discharge valve, oh i’m sorry I see you have one of them modern digital manifolds that won’t show things like that, oh well maybe it’s also a radio to keep you entertained while your working. Also your liquid line should be warm to the touch, NOT HOT, and NOT COLD, one could indicate a dirty condenser, the other a plugged system and be careful, Carrier likes to sandwich two coils together on some of their units and they get dirty in between where you cannot see ! Never cared much for Carrier and I can’t stand Trane.
There are a number of ways you can fail by using superheat only.
Subcool is used on TXV controlled units to insure there is sufficient refrigerant to feed under all load conditions. Placing a sight glass on a modern A/C unit controlled by a TXV will not give an accurate charge. We are far beyond that. It is kind of 1970s tech.
An A/C unit with several cap tubes, superheat can be normal with one tube blocked.
An incorrect piston can also give you incorrect superheat.
Air in the system will also give an abnormally high head that will increase flow in fixed orifice systems and lower superheat.
Low airflow across the evap will also give you correct superheat on a system with low efficiency.
Gauge readings must also be checked.
There are more, but this will do for now.
I would suggest that the hand on the suction line be supplemented by correct gauge readings, temp probe on the liquid line, probe on the suction line, a check with manufacturer's instruction (located on the model plate), ambient temp probe to determine if the gauge readings match, temp split across the evap.
I used this method on all systems I worked on. It takes little time to set these probes and they will save you from mistakes.
GFM
grayfurnaceman I edited my comment, I assumed monitoring your gauges was a given, you will see that everything you said in your comment is addressed. Any of the problems you presented will show up if the technique I presented is followed, now diagnosing that problem will depend on your technical abilities. And about your sight glass comment, a sight glass is the only fool proof method of insuring a solid column of liquid to your expansion valve, I don’t care what they taught you ! And I find that 70s technology comment pretty funny, I didn’t realize the laws of thermodynamics have been changed ! Want to talk about something, let’s talk about the modern engineering marvels I have been running into lately, like using flammable gasses for refrigerant, i’ll bet you even think the insane pressures of R410A is going to work out, just make sure you honor the 5 year warranty on these compressors in the units your installing as they start blowing out left and right every time the mercury cracks the upper 90s.
Question about a R410A systems, when the system’s compressor won’t energize due to low refrigerant with the low pressure switch, and you have a few lbs remaining in the system, can you charge as liquid directly to high side with compressor off? That is, weighing it in until system won’t accept any more, then, topping it off via subcooling method via low line. Or, must system always be in a total vacuumed state before you can ever do so? Moreover, in what situations can add via high line as liquid.
Unless the charging cylinder is at a much higher temp than the A/C unit, it will not move. I would not consider it viable.
The only viable method of liquid in the high side, is with the system well below saturated or, of course, evacuated.
GFM
It seems then just holding down the contact switch, going into low line is the best way, versus using warning blanket on cylinder.
Or, if system is short cycling due to low charge. that's probably good indicator you can go into high side?
@@userjim9 I have never been a fan of warming blankets.
Jamming the contactor or bypassing the low pressure switch is viable, but short cycling will not change the inability to charge in the high side.
GFM
Bravo.
Sorry, just to much jumping around and not clear with your explanation. Very hard to follow. Just my opinion.
Sorry it did not work for you.
GFM
This man has taught me more than school every did.My hats off for you sir.
🤔😂🤣
Same here lol
great refresher, felt like I was back in school again, keep up the good work Professor Grayfurnaceman
Paul.... If a R410 unit is low when testing on a service call or check up, that means the R410 is unbalanced with concerns to oil mixture. R410 requires the precise mixture for it to cool properly and oil sufficiently. Only if the unit is brand new and just requires a top up then can you just add. Otherwise the system (by manufacturer specs) requires you to recover and start from 0 if the unit is found to be low
Right. It is no longer the original blend as the different refrigerants will leak or at different rates.
Just like I learned in school... Although there wasn't any creation called R410a back then. We had it easy with r22, blended refrigerants are a pain... Lol. Good video as always Gray. Thanks for all the knowledge you pass along to all of us.
I would expect the subcool to be the same.
GFM
I didnt notice any recovery machine, i hope you didnt do any atmospheric recovery. just messing with you, good video. id like to add anytime i get into a system that is low, i will leak check first, and i always change out the schrader cores on all ports that have them. as well as clean all coils and change air filters first before taking any readings. I just dont like having call backs
You are The First mechanic among all the Super Techs on you tube that stated the obvious=Back to square one=clean coils,air filters leak test and repair.
Good on you mate.
Just my two bob worth : R-22 systems can be toped up as for R-22 is not a blend. R-410 and other blended refrigerants should be dumped and recharged with virgin stock. Change filter/dryer.
Greetings from Australia.
If only all the customers would pay for the right job to be done too many moron techs give them too many options and taint their minds it should be stamped and said this is proper code and has to be done like this
Sir ....ur the man....
i wish there was utube when i was in school or better yet u were the teacher...i learn alot from ur videos....thank you so much ...really appreaciated!!!!
Thanks for the support.
GFM
Another superb run-through for how to adjust charge in an R410A split system with a TXV.
I’m finalizing the charge in a similar system right now. It has a brand new condensing unit, but I am still using the existing evaporator and line set. So I knew additional R410A would need to be added to the pre-charged amount which was already in the new condensing unit. It required about 3 LB to be added. I think I’m getting close to the right amount now, but will make one more test of subcooling, indoor supply vs. return air temperature split, and superheat exactly like what is shown here in this video.
I have one of those SMAN4 gauges along with the wireless sensors and transmitters. No need for any math, once set up, it reads the superheat and subcooling in real time. This allows me to very quickly zero in the correct charge and squeeze out the highest efficiency the unit is capable of.
I personally, have a lot of problems in charging system with the TXV & Receiver. I think this give me a lot more clear than before, but if you have more example of charging, please post it. I am so grateful that you are sharing your experiences. John
chandarasena This playlist may help: ruclips.net/p/PLItXrh64d2JNue0B3iGRSAPpPgni6mcqS
GFM
I did residential for 7 years, I'm currently working for the last 7 1/2 years in big commercial equipment. I started looking for any videos HVAC because I always believe that in this trade is always something new to learn and I found one of your videos and I was hooked. I wish I would it have an instructor like you when I first started in this trade, thank you sir!
+bladimir becelinoff Welcome
GFM
Thanks for the support.
GFM
bladimir becelinoff will get
I have the same problem . Over thirty years working on systems that hold 50,000 lbs of charge to half an once . Something is always done with a different method to the madness
!
Hey mate, I saw another video of a guy adjusting the superheat (on a walk in cool room) by adjusting the TXV. This is incorrect right? The only way to do it is what you have done in this video by adding refrigerant to get the correct sub cooling..? Also I always thought it was bad juju to charge a system with liquid or is it ago to do it by adding slowly?
I seldom adjusted TXVs. It would be among the last things I would do when encountering high superheat. Charge levels are best determined by subcool. Blend refrigerants must be charged as a liquid. Liquid charging can be done either high side with unit empty or low side by metering the refrigerant to avoid liquid slugging of compressor. Hope this helps.
GFM
I really like watching this man explain, in common sense terms, what is going on and what he is doing....The videos are always excellent.
Isn't the 11 degrees of subcool rated for a 95 degree outdoor temp? And for 410-A, a good suction pressure is around 120 and a good head pressure is around 420 (also rated for a 95 degree outdoor temp). Shouldn't you drive the head pressure up to around 420 to simulate what the manufacturer recommends? 11 degrees of subcool at 84 degrees outside won't be the same on a hotter day.
According to Trane, the sub cool should stay the same at all temps except below 55F outdoor ambient. It does seem that the sub cool would drop with higher ambients because of the additional boiling refrigerant, but it does not seem to be true. However, I will test it at higher temps and do a video on it. As for the suction pressure, If the system is designed and working properly, the suction pressure will correspond to the indoor air temp and wet bulb. As far as I know, no manufacturer recommends simulating 95F for checking charge.
GFM
I'm still a fairly new tech (3 yrs. exp) and still learning the more specific technical details for individual units and systems. I would like to ask, when the information is not present on the unit,for example, older unit with faded tags or new one with missing paperwork. How do you go about finding out the exact specifications for what the unit should run at,as far as subcooling/fan cfm/or static air pressure? Thank you for your time and good video.
Ah, the age old question. Throw in mismatched outdoor unit and evap, and it really gets tough. Target superheat can be used if it is a fixed orifice. TXVs are really pretty simple. You probably will not go wrong 11 to 13 subcool. Fan cfm can be handled by delta T across the coil and evap temp. If the evap temp is below 40F with normal cooling ambients, cfm could be low. Static is quite variable with different systems. Hope this helps.
GFM
I know this is a training video probably at your house but would it not be good to mention that if a tech gets to a R410A unit and its found to be low on refrigerant that the unit should be recovered and all new freon put back in so that the right amount of mix is in the unit?. just a thought
Colin G You need to explain further. Are you saying the refrigerant should not be replaced?
GFM
+grayfurnaceman What Colin G is saying is that if a tech sees that a system is low on 410a, the tech cannot know how much of R32 or R135 (the components of R410a) has leaked out, so in order to get an honest R410a in the system, the tech should recover the old refrigerant and add all fresh R10a.
That could be pretty costly if it only needs a small amount to bring up to full charge, having to dump the full charge and reinstall with new refrigerant. Can
the proportion of the existing mixture be determined by checking the stabilized vapor pressure at the ambient temperature? For a proper blend of R410a, there should be a specific pressure corresponding to the ambient temperature with the system off and given a chance to stabilize. If it's off, maybe adding the lighter component to restore the blend could be done instead of adding the R410a blend.
Something like making a measurement of the specific gravity of antifreeze and adjusting by adding coolant or distilled water to achieve the target specific gravity.
Otherwise, is there an electronic method of reading the blend components in the system?
Great video. I do have a question. I thought if you were charging by superheat, you should attach the temp probe near the suction service valve. Thanks for the video
its a TXV, you charge by subcooling.
Nice video. Thanks!
Actually is one the better videos addressing this topic than many I have seen in the past.. great job.
Thanks for the support.
GFM
thanks for sharing your knowledge. I value your experience. thanks
Josh Hdz. Welcome.GFM
Excellent video probes that when u have the time and the dedicated tools the charge would be pretty close to perfect.....One must be careful about Microchannel Cond. Units that can be overcharged very easy running most times into Overcharged High Head Situations specially on 94 degrees temp summer days....tnks
what do you mean by comparing the ambient temperature to the condensing temperature?
also why was the sman showing 16 degrees superheat, is that because you measured superheat outside instead of inside?
hi, doesn't that affect the compressor when adding liquid into the low side like that? thanks.
It will affect the compressor if you add the refrigerant too fast. Watch the video again and pay close attention to Grayman's instructions! Good job!
You can use a liquid charging adapter when charging. A liquid charging adapter is basically a fitting that has a small orifice in it to prevent liquid slugging. A liquid charging adapter is just cheap insurance.
r410a system ( with fixed orifice) with equalized pressures of around 200psig. But once compressor starts the low side drops to 50 psig while the high side goes up to 300psig. I checked superheat was like 80F and subcooling was 2F. Does this mean the system has leaked out all the refrigerant? Does the 200psig equalized pressures means there's refrigerant in the system? thank you.
All the 200 psig means is there is enough refrigerant in the system to make a saturated mix. You could be quite low on charge.
GFM
Hi, my r410a with txv unit. The suction saturation temp is about 33F and suction line temp is 48F giving 15F of superheat. But why is my liquid line saturation temp is 97 and my liquid line temp is also 97. I tried adding some refrigerant but nothing changes. This is a high velocity system air handler with a slab coil. I think my suction saturation temp is also too low. Both coils are clean and txv valve is new. Any help would be greatly appreciated. Thanks
on a new out side unit with nu22b add charge low side or high side? apt maintenace
techs do different sides what is correct.please help thank you gfm
***** what is the best way to charge liquid in evacuated system thru highside or lowside? thank you for all replys and videos
You must charge liquid thru high side in an evacuated system. If you charge thru low side, you will put liquid into the compressor and it may slug when started.
GFM
Paul.... If a R410 unit is low when testing on a service call or check up, that means the R410 is unbalanced with concerns to oil mixture. R410 requires the precise mixture for it to cool properly and oil sufficiently. Only if the unit is brand new and just requires a top up then can you just add.
Otherwise the system (by manufacturer specs) requires you to recover and start from 0 if the unit is found to be low
Thanks for the videos I'm currently studying to become a Hvac technician and your videos really help me a lot
+Carlos Chavez Welcome
GFM
+Carlos Chavez Welcome
GFM
410 is a 3 way blend. Charge one system via gas and you diminish the quality of the rest of the bottle proportionately to the number of times its done like that.
Question:
So on my new Ruud 3.5 ton AC with "N" coil, using 34 ft of (3/8 liquid & 7/8 vapor) lineset. I know to add .6oz per foot over 15 ft. but was curious if it was necessary to add extra 410a to account for the copper elbows?
I have three 7/8" elbows and then 2 long hand bends for the 3/8". Cant determine if they are telling me I need to do this no matter what or just if I have a long lineset and high vertical rise which I do not have. Lineset goes 8 feet up from AC service valves to ceiling then 22 feet straight to furnace room and then 3 feet down with the 2 elbows to connect to coil. Manual states, All units are factory charged with R-410A refrigerant to cover 15 feet of standard size interconnecting liquid and vapor lines with a required field installed filter drier. I have installed the filter drier inside before coil and coil also has TXV installed with bulb of course at 10 o'clock position on vapor line also on outside of cabinet.
you charge to superheat at evaporator outlet if it's a cap tube metering device. subcool for TXV. good video GFM.
will you please stop smacking your LIPS!!! thx for the videos otherwise!
johnny danger Can't do much about that.
GFM
+Johnny Rotten John so you also want milk with your cookies lol
I thought that Gary had "just a pinch between yer cheek and gum".
You said you were gonna do a video on recharging-subcool-superheat ect, and you kept your promesse. Thank you so much. It changed few things in the way I was doing it like taking the low pressure temp after the evaporator for superheat.instead of outside. If ever you have some trick to solve slow leak, you would make my day. Thank you
Maybe you shouldn’t make videos
I would be interested in your thoughts.
GFM
Good video as always, but I wish you would show where your probes are placed for your various measurements. As it is, some parts are confusing without that context. It would also help to mention alternative ways to get the saturation values without a digital gauge set.
thanks Mr. Gray
20° is a bit high across the coil. May want to increase the fan speed a notch to increase efficiency. Great video and information 👍.
Super helpful. Very good details and explanation.
bul
Thanks for your help in making it simple to understand!
I'm curious to learn what would my subcooling look like with a bad TXV.
H
Too confusing for beginners. He keeps moving back and forth to different temp readings with no indication as to what the heck the temp is measuring. Which temp probe is connected to which line? And, why is it important to know the ambient temp when you're doing subcooling? And, he keeps moving back and forth to various readings, just reading off numbers. so fast that it makes your head spin. Terribly confusing video for newbies.
Charging is not a beginning subject. Its more toward the end. I have many videos on A/C that may help on my channel.
GFM
Paul.... If a R410 unit is low when testing on a service call or check up, that means the R410 is unbalanced with concerns to oil mixture. R410 requires the precise mixture for it to cool properly and oil sufficiently. Only if the unit is brand new and just requires a top up then can you just add.
Otherwise the system (by manufacturer specs) requires you to recover and start from 0 if the unit is found to be low
+Colin G When a blend has a leak in the liquid side, the refrigerant will leak the highest pressure refrigerant at a higher rate than the lower pressure one. R-410A is a blend of R-32 (50%) and R-125 (50%). It is called a near Azeotropic blend. Meaning it almost leaks at the same rate for both refrigerants. At approx 70F R-125 boils at -55F. At the same temp, R-32 boils at -61F. Looking at the different boiling temps there is only 6F difference. Remember, both refrigerants are leaking, with the higher pressure one leaking slightly more. With these numbers in mind, a small leak can be topped off (after the leak is repaired) with refrigerant without changing out all the refrigerant. Certainly, if there was a large leak, the refrigerant should be replaced. I have never seen a manufacturer claim that a small leak must have the refrigerant replaced. If you have other specs, I would like to see them. Thanks for the thoughts.
GFM
Very good video . I have Question pls
If he charge with sub cooling when there is a TXV and by wet b dry b on the super heat with non TXV . In what category fits units with capillary metering device. And one more q. If I was to do sub-cooling calculation on a R410a split in cooling mode do I doit in test mode ? Full fan run speed? 18 Celsius set temperature? Thank you
+lucly nn The capillary device is also considered a fixed orifice device and is charged by superheat with wet build and dry bulb or target superheat.
GFM
Best video! even better then school haha
Question what's the best target SH and SC?
Good video. I appreciate your candidness about recover and refill vs. top off. It is first I have seen with that viewpoint. As a DIY guy, this means I just need a decent manifold set, a scale, temp probe(s), and jug of 410a. I will leave the other tools to the professional when it is time to have serious repairs performed. My unit has been serviced 2 times, 2 diff techs. Neither one found a leak, both ended up charging it up and that was it. Strange observation on my part - it appears to leak when it is powered off for an extended period of time. Crazy.
Leaks can certainly do that.
GFM
Love that manifold …..did some refrigeration many moons ago . We didn’t have that , had to do all the superheat and sub cooling by math , wonder how much it cost …thanks a lot for the video ! You explained and a few minutes what it used to take weeks to grasp
I think it was about $300. Glad it helped.
GFM
Some posts are questioning if the system is low on refrigerant that you need to recover and start with Fresh . how serious is this ? you added 3.3 lbs that sounds like alot My 3yr old system has a leak and 3.2 ls was added . should I turn off unit until they find leak and recover and recharge with fresh R410 A ?
Whether to recharge with new is dependent on several factors. TXV controlled units are pretty easy. Charge until subcool is right. Fixed orifice is a little harder. Sometimes remove and recharge is the best way. You can also use target superheat without removing the charge. This is assuming the system can be pumped down for leak repair.
GFM
Thanks Can you describe the several factors ? Why does the ease of charge have anything to do with the R410 being reused . I have heard the mixture proportion is critical and just topping isnt an accurate blend. if large quantity is added . is that true ? 3.2 sounds like a large % of an 8.8 full system . Tech said he can pump all refrigerant back to od unit then replace evap coil if leak is there . I still have questions of proper mix volume when adding 3.2 lbs . Still I dont want to pay for 8.8 virgin A410A if not necessary Please advise .
Mixture proportion is critical. However, R-410A has 2 components whose pressure difference is only about 3#. This means you would have to lose most of the charge before any effect could be noticed.
GFM
0n my 8.8 (tag stated) lb. system, we had to top up 3.2lbs to reach subcool of 8. Tech .stopped at 8 deg subcool and unit ideal is 10 +,- 3. . I guess additional could have been added to hit 10 sub on the mark . I heard HoneyWell did a test at 50 % loss and top up numerous times and no negatives to system were found .Looks like even with my line set of 30ft and evap capacity my compressor is safe . Now to find that leak . BTW 2 yrs ago the OD unit froze up ( winter) and shut down due to defrostboard failure 2 or 3 times . Is it likely the high pressure caused a leak in the OD unit ? Tech wants to pull all R410 into OD and test lineset and evap first . Wouldnt checking OD firstt be more practicle ? We havnt seen any oil or discolor anywhere as yet .Sorry so long but I do apprieciate your knowledge and experience .
i read about "target" subcool and confuses me, and i read about return wet bulb temp has to be considered on the equation also, can you make a video on that?
***** thank you sr!
went to fcc and still dont wana go to that place
I am fresh out of School green horn. I very much like these videos has reminders and when I get stuck not rembering exactly what to do. Practice and "learning opportunities".. thanks again for very straightforward information.
+Bobby Dean Morgans II Welcome and good luck in he field. Never stop learning or it will pass you by.
GFM
So with TXV the superheat should always be no more than 15 psi if the valve is working right, even if the charge is low?
quimshtgclg With air conditioning systems, unless manufacturer instructions are different, 15 DEGREES F of superheat is about the highest. If charge is low, superheat will increase as there is not enough charge to maintain superheat. Hope this helps.GFM
Thank you very much for your teaching I’ve been learning allot from your videos, I feel that I’m better technically,God bless you for your teaching thanks again for taking your time to make this videos
Welcome
GFM
Great video and good thorough explanation! So the greater the efficiency the less you add to the ambient to get total condensing saturated temp? Like in a standard unit it's ambient plus 30 so in these high efficiency units it's plus 20? With every passing year the standard is getting higher. Will that mean that eventually we will be adding less and less to the ambient? Thanks for your wisdom!
The first reaction of manufacturers to the need to increase efficiency was to increase the size of the condenser coils. This, of course, reduced head and did increase efficiency. It was also the most expensive way to increase efficiency. So, manufacturers have changed things like compressor design, TXV design and fan motor design. The actual size of condensers has again reduced and the efficiency goals have been reached.
GFM
Thanks for the video. You cover a lot of great details to watch out for. I am curious what the specific advantages of a TXV are over a fixed orifice for the evaporator. It would be interesting to see a video on an r-22 superheat charge with a fixed orifice.
I am working on that now.
GFM
what brand digital thermometer are you using? not the fluke, the black one.
Its just a cheapo from China but it is quite accurate.
GFM
Great job save me a semester of school lol
What do you do if your unit does not have a subcooling chart? Is there a standard? I have an ICP Heil PGAD30D1K7 and cant find a manual or subcool chart. I am getting 10 degrees with the probe and gauges. Thoughts or help is greatly appreciated and Thank You.
The unit could have a fixed orifice. Subcool is important on fixed orifice, but most units are charged by superheat.
GFM
Wow, Thank You for taking the time to reply to my post. I checked and it has a TXV but darn if I can find a the required subcooling requirement for this unit. It does have 10 degrees sub cooling and cools well. I just want to make sure it should not be 15. Have a great weekend and again Thank You. v/r mw
Excellent Vide and information. Thank you for sharing !
Welcome
GFM
The charge is still not accurate. Evaporator shows signs of restriction.
+brandon milner Just got your comment. I assume you are looking at the suction pressure. Note the return is at 70F. If you had a normal 75 to 78F, the suction would be higher.
GFM
when charging by sub cooling and you get the charge right, how do you look at the super heat and determine if the txv is working properly? No one ever says what your super heat reading should be. They just sat " the super heat looks good" Whats a good reading and why??? I've read to never let super heat get below 20-25.at compressor, always check line temp. at same place you are taking pressure reading. If I could get this question resolved, I would understand super hear and sub cooling much better. Counting on you furnace man.
The txv is design to maintain a superheat of 10 degrees under perfect condition. depending on the load at the evaporator that number can be between 5 and 20 degrees, if you are out of that range......there is a problem
how do you like those gauges? was thinking of grabbing a set
I have had no problem with this set.
GFM
What is the reference in determining the Temperature Difference Between the Evaporator Coil?...Thanks a lot for sharing.
trharesco It depends on the application. Generally, the split should be between 16 and 22F. I will be doing more videos on temp splits this summer.
GFM
grayfurnaceman Thank you very much for the reply and looking forward on the video about the temp splits... thanks for you sharing the knowledge....
I got a question I'm pretty new to the Hvac field...in class we're currently doing a recovery and a vacuum and the instructor told us to buy out own gauges so we can get used to using them.....now my question in your opinion which digital manifold is good for a beginner but also good enough to have out in the field price is not really an issue.....thnks
+Carlos Chavez The Testo and the Fieldpiece are the most common choices. I really have no problem with either of these. They are quality products. I use the Fieldpiece but that is mostly because it is easier to see on the videos.
GFM
+grayfurnaceman thanks for the reply I went and bought me a testo 550 and I excited to try out..thanks again I'm really understanding more about the Hvac system just by watching your videos 👍👍👍
Is that a Craftsman lathe in the background? :)
Yes, its an oldie and maybe not so goodie.
GFM
Good stuff dude.
Good stuff
Love your VDO easy to understand thanks
Welcome
GFM
thanks man..... these r410 cylinders come with a dip tube... so is necessary to keep the cylinder upside down to ensure liquid entry?
I have never seen one with a dip tube. If it does have one, you would charge with it upright. It is noted on the cylinder with an arrow.
GFM
Thanks a lot....what is the pressure in a new fully capacity r410a cylinder?
The pressure depends on the ambient temperature. You can find temperature pressure charts on the internet.
GFM
so you finished with a saturation temp of 102 and a discharge line temp of 91 to get the sub cool of 11?
+JasonKraft Yes except the line is the liquid line not discharge.
GFM
+grayfurnaceman thanks for the reply and all of your videos are very educational
Hi, i was wondering if i need to bleed the air out of the hose by unscrewing the hose from the gauge first?
Whenever installing gauge set, all hoses should be bled at the gauge set.
GFM
@@grayfurnaceman wow thank you so much for the quick reply! Your channel has been really helpful to me. Cheers!
For manufacturers whose installation manuals advise to add additional [R-410] refrigerant for indoor matchups and/or longer line set lengths will the resulting subcool value be higher than their suggested published value? I.E. if they recommend SC of 9 based on a charge of 11.7 lbs. is it possible to see, say, 14, if you add an additional 2 lbs due to the indoor coil matchup and longer line length?
Brian Fletcher most AC systems have lists supplied with the AC that tell you how much refrigirant needs to be removed or added when line length changes.
Brian Fletcher The adjustments are to keep the subcool the same when adapting longer linesets or different indoor coils.
GFM
grayfurnaceman Thank you, GFM; that one has had me confused.
thanks for all you do! You are a very good teacher.
Welcome
GFM
What about adjusting TXV when subcool is correct and superheat is high?
In my career in HVAC, in 35 years of repairs, I have adjusted a TXV perhaps 10 times. In at least 5 of those times, adjustment of the TXV did not help. Look for everything else first, adjust last.
GFM
+grayfurnaceman, thanks you Sir!
You are sharing great knowledge!
👍
Happy new year.
GFM
Thank you master!
You have a wonderful and a happy new year too!
may have these instruction in french ?
+jean-robert lavallée I can't figure out how to do it.
GFM
good lesson
That was a very helpful presentation thanks a lot! 3lb charge does make me curious as to what leak you repaired because that sucker was dry.
4842Chuck The unit was being used as a test mule. It had no leak.
GFM
@@grayfurnaceman You said you recovered some refrigerant from the unit prior to testing so you already knew it was low. Good job. Chuckyoufarley made a good point.
Thank you for the info.
thank you
Good Video
do you like the fieldpiece gauge? im thinking of buying one... any review would be nice.
Kyle Faubertq The Fieldpiece is very good. Mostly the competition is between Testo and Fieldpiece. The primary reason for the use of the Fieldpiece in my videos is the larger numbers for the videos. Both of these products are very good. When I get a chance, I will be doing a comparison. Hope this helps.
GFM
Thank you, I would appreciate that.
thanks Mr for your time
great job
Welcome
GFM
thank you...
Personally I think he needs to explain what all the terms are... and show where he collects temperatures.
This is not an entry level video. Some assumptions of prior knowledge is necessary.
GFM
grayfurnaceman I think you are right. A review of terms would have helped me but maybe mot everyone. Thanks
I intend to make up a series that teaches the basics with all the terms and methods. I just have not gotten around to it.
GFM
thank you sir for teaching
Welcome
GFM
U need to study the txv again
Tim Nies Then I think you should do a video on how to do it right.
GFM
awesome explanation sir!!
Thanks for the support.
GFM
Awesome video well explain
Emil Falck Welcome
GFM
Great video gfm..
jon50harding Thanks for the support.GFM
I cant wait to get my certs in. I always wanted to do this type of work.
thanks for the great video's. this is way better then the typical schools I see people going to
Daniel Furlong but are you ready? Test question for you. You have low pressures low superheat and a low suctionline. What's the problem
IMon Trust me when i say I have very little experience.
I always start by checking the airflow , making sure both coils are clean and filter is clean
I would think if freon levels are low, If freon levels are normal, Insufficient heat getting to Evaporator .
Overcharge of freon can cause the same problem also possible restriction at the caps
I'm only going for my universal test atm It looks very easy. After i pass the test i will try to get on at a local A/C company to get better experience .
Daniel Furlong good doing on checking for airflow on everything. Lack of airflow on an evaporator will give you low pressures with a low superheat and cold suction line. You gotta run the system for 10 minutes before determining a problem with your refrigerant.
Lack of airflow problems are dirty evaporator coil, dirty filters, undersized duct. Crushed duct. You'll usually get a block of ice.
Daniel Furlong learn how to use your gauges to read problems
Great video.
Glad it helped.
GFM
What lathe is that? Do some video
+profuse007 Are you talking about the Monarch?
GFM
+grayfurnaceman yes
+profuse007 I have not thought about it. It could happen.
GFM
Great vid Gray.
Listen Gray I'm thinking of purchasing a set of digital manifold gauges like your using.
Are you up to date on which unit is a good unit to purchase at this time......?
I thought your indoor and outdoor temperatures didn't matter with TXV systems. I thought that as long as it's running desired subcooling, and the superheat is no more than 12 or 13, it was good.
John Smith TXV systems are better at lower ambients, however air conditioners run at fairly narrow indoor and outdoor temps. On residential systems, outdoor below 70F and indoor below 70F the numbers cannot always be trusted.
I happen to live in Arizona, and it can get over 118 degrees here sometimes. Let's say my indoor temperature is 70, and my outdoor temperature is 130, if the system uses a piston, will I have any superheat under these conditions?
Is it possible for the outdoor temperature to get so much hotter than indoors that there might not be any superheat? If it is about 70 indoors and 130 outdoors, would that be enough to cause zero superheat?
John Smith Superheat is for all conditions. It's a troubleshooting tool that is used in all conditions. A term. Same for subcool.
This is just one example of the lack of ability of HVAC service Technicians to diagnose problems and fix them. My brother had a 1.5-Ton air-conditioner installed on an oil furnace that only had a quarter horsepower blower motor and they installed an evaporator coil directly on top of the furnace which resulted in it being to close to the furnace heat exchanger causing an airflow restriction.
Actually in that oil furnace the quarter horsepower blower motor should only be used with heating and never less than a third horsepower motor used when there's an evaporator coil Installed in the system. the evaporator coil was always heat under loaded.
Additionally, the system almost immediately begin to lose charge in the area of the evaporator coil. The first tech who came out with had an analog manifold gauge on the suction line and saw that the pressure was normal, however, the system had a TXV metering device on it and therefore you have to charge by sub cooling and of course he didn't have any way to check either the superheat temperature or the subcooling temperature; therefore he misdiagnosed the system as being okay.
Over the years the same company was called in; again a total non-diagnosis was the result. Then another company was called, which I thought they might be the best company; however, he merely removed a clean return air filter; he had a set of digital manifold gauges which showed the superheat and sub cooling of the system. Subcooling was only 1°F and normally you need 8 to 10°F of subcooling on a TXV system.
However, when the superheat got down to around 16°F and the thermostat expansion valve superheat target was probably 12°F; the tech said the system is overcharged and he took the manifold gauges off the system. However, the sub cooling was only a mere 2°F; he left the system still way under charged, he never searched for the leak, nor diagnosed extremely low airflow through the system indoors resulting in situation where you couldn't possibly properly charge the system.
This is only one example of how the technicians here in the Southwest Wisconsin area, where I am now living, simply can't seem do anything right, it is difficult for me to believe that HVAC service work could be that bad, but I believe the number of service technicians that do their work correctly is a very low percentage. our HVAC industry is shamefully disgraceful condition…
Hello.
Is there any way to calculate subcooling for INVERTER AC without having good measuring instruments ? I have 12000btu AC ( 3500 W) r410a and is not working as it should. I live in Europe and I use it for warming up my room in heating mode. After all calculations I did and after all possible error is still far from specifications. I only have low pressure from the day it was installed : 100 psi. It was 93 F outside in that day. I kept complaining about efficiency at installer and they came last days and measured again pressure, suspecting leaks. It was again 100 psi. He started recharging using gauge only and it reached arround 130-160psi then compressor stopped. He removed refrigerant until compressor is on and that's it. When he left he measured arround 115-120 psi low side and 460psi high side. This unit has only one port for gauge measuring and high side was measured on heating mode when pressure was high. This technician doesn't have other instruments for measuring this unit except pressure gauges.
Unit is working a little better now. There are higher temperature at inside unit. It was about 115 F before and now it gets 122F but there is a major change in time it gets to that temperature : it takes much longer. Before , at lower pressure it didn't passed 115F but it was fast. Now it gets after double time at 122F. Room temperature is arround 77F, outside temperature is 53F.
Is it working good enough ? Can I measure suction temperature near outdoor unit and find out subcool ?
+Laurentiu alien24cl These units are charged by weight only. The leak should be found the the charge weighted in.
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