How to handle frozen evaporator coils
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- Опубликовано: 28 авг 2024
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I’m finding this class very informative and well tought. It’s been 40-45 years since I handled refrig/hvac. And I’m wanting to learn again. Thanks !
This is probably one of the most informative videos I’ve listened to.
This is a great video !! Easy to understand and yet it also made me think.
A video on Heat Pump Hot Water Heaters would be great as there seems a lot of voodoo around them.
(18:07) Wow!
This video is phenomenal. I learned more about the evaporator coil and airflow in this single video than I have from watching videos from other RUclipsrs AND from my instructor at school.
I am so glad that I found this video and subscribed to your channel!
My instructor at school actually taught us incorrectly regarding a refrigerant's pressure/temperature relationship! He told us that the more refrigerant there is in a system (or container), the higher the pressure will be.
Period.
Granted, like you said, quantity IS one of the determining factors. However, it isn't the primary factor that is ultimately what causes those pressure changes to occur. And because he failed to elaborate further on the subject, we were left ignorant of the situation.
All we have to do is look at a P/T chart from a different perspective: Instead of saying to ourselves, "Okay, this R-410A container is 208psi, so the refrigerant contained inside must be 72°F.", we need to instead say, "The ambient temperature is 72°F, so this R-410A container SHOULD be at 208psi." If its psi is higher than that, then it is either over-filled, or there are some non-condensables trapped inside...
Love your videos, big guy; please don't stop teaching us. 😏
Glad to see you back. Honestly, imho your videos are more informative and better presented than any channel i have seen on YT. I rarely have to rewatch parts of your videos.....i understand the first time. That is what I like best about them. Thx.
Thanks! Glad you find it useful.
Great job explaining everything thank you very much!
Wow what a rookie mistake that guy made. Charging with a frozen coil. I can’t believe he didn’t let it defrost and. Come back later to check. Can’t believe he had 10 years of experience. Maybe he never learned the basics. Could have been a low charge, a restriction, low load from restricted airflow, low head pressure from running in a low ambient, etc. you can tell by the look of the frost, or ice. Frost means it happen Fairly fast where a restriction or shortage frosts at the beginning then moves along, forming mor of an iced look. If the suction line frosts soon after starting, it is from low airflow. You my friend are a very good teacher
01:22
Dear Eric,
Thanks alot. You are awesome. What a what of explaining a problem and solution. Your presentation is amazing. I have become a fan of you sir
What a way*
Wow, thanks!
Hey brother how are you ?
Make please more video about subcool and superheat maybe about refrigeration stuff summer coming.
Like the way you explain .
We were on an 8 system maintenance We found three of the 16 seer carrier units with very low pressures in a little bit higher than normal head pressures and all three of the capacitors were about the Fail. ❤ for today. Was getting about 101 and 360 on a 86° day afterwards was like 128/330😮😢🥳😎👍
That’s not rare in South Florida that’s every day lol❤😂😂😂😂
Fascinating. I really enjoyed following this through.
iced up coilatitis song by nor-cal is also pretty informative on this
Great class and great video keep them coming 👍🏻
The most common here in south Florida is what you just mentioned low on refrigerant blower motor failures constantly and TXV‘s with the rare contactor problems and that order 123 and 4 With a lot of cases of dirty coils and filters because they run all year long❤🎉😂
Awesome video and lesson !!!!!!!
Thank you very much
You are welcome
If it stays at 23 to 29° it’s gonna freeze regardless how much refrigerant in there. Like you said earlier if it’s totally full or totally empty it’s all reliant on the temperature going in and out of that coil🥳😍🥶😱
23:30 - Technically, the compressor's job is to create a pressure difference by raising the pressure at its outlet and lowering the pressure at its inlet. The job of the metering device is to create a pressure difference in the opposite direction.
46:46 - When you say temperature drop here, are you referring to TD, or ΔT? 48:00 - OK, you answered the question, here (i.e., ΔT, which is the difference between the return and supply air temperatures and _not_ temperature difference - TD, which is the difference between the air temperature and the saturation temperature of the refrigerant).
Thanks for that wonderful ideas
Always great content and thanks you Always
I have found hundreds of coils that were frozen due to just lack of refrigerant from my guys out there plus what I found myself so I take it that’s have to say that was on the top three😮🥵🧐
Always enjoy your presentations! One question in regards to the fan cycle switch. Is there a chart or reference I can access to determine the proper psi for the switch? I assume high side fan switches comes in many different psi settings. Thank you!
For the encapsulated non adjustable ones, you select them based on the refrigerant used.
Should also have a low pressure switch and or a LA T sensor or freeze stat on the suction❤ we use
Neither all four have to work❤ ❤ ❤ ❤
30:48 - I was taught the complete opposite.
When a unit is low on refrigerant, your manifold gauge will show high Superheat, low Subcooling, and low pressures on both sides. And since temperature & pressure are directly proportional, the lower your temperatures, the lower your pressures. You even confirmed this at 33:22.
Would you please elaborate on my confusion here?
Thanks.
This is a very insightful question. I apologize for the delay in response. To be clear, we need to differentiate between the temperature of saturated refrigerant which follows the pressure / temperature relationship you mentioned and the temperature of superheated vapor leaving the evaporator in the suction line which does not follow that relationship. High superheat will be the case as you mentioned. If you start a unit that has low refrigerant with low suction pressure and a saturation temperature of, say, 20degrees (well below freezing) and a high superheat of 25 degrees, the suction gas temperature leaving the evaporator will be 45 degrees (well above freezing). Hope that helps clear things up.
@@hvacservicementorOh man; thank you so much. That most def cleared things up for me.
I've been in the field for 2 years now, and never considered that superheated vapor doesn't follow a pressure/temperature chart. I always assumed that, no matter a refrigerant's pressure, you can always convert that to a known, relative temperature.
Sounds like a zoning system lol❤❤😂😂🎉🎉
Don’t forget your stinking contactor in the dirty filter🎉💯🔥
Why the evaporator coil of my home AC freezes at night? During the day no problem.
I had a customer call said the unit was freezing up we get out to the job and I noticed a big hole in the return plenum the size of a license plate I asked the customer what the hole was about he said the other company said there was not enough hot are going into the unit to keep it from freezing I just 😅 I fix the hole in the plenum check the air filter that was clean check the pressure thay were good so I sat there and watched the air handler the blower fan would shut down and start back up a couple minutes later we replace the blower motor everything is good some technicians are not technicians
Sitting and watching. A very important part of the diagnostic process.
Good video, one question, checking RH , where about location should be? Close to return or middle of the room? Close to thermostat?
When checking RH, we are interested in what the Evaporator sees. You want to measure RH as close to the inlet of the evaporator as possible. Usually, this is in the Return air stream at the air filter or main RA intake grille. If there is a outside air duct joining the return trunk between the RA grille and the evaporator, that can throw things off a bit.
Typically the evaporator skin temperature is about five degrees above saturated suction pressure so R22 won’t ice until about 52 lbs suction. There is a loss because of circulating oil, and heat transfer of the evaporator material.
Is it possible for evap to freeze due to being overcharged?
HI, what is the formula you use for the table in 48:00 ?
That table was extrapolated from the old slide charts that major manufacturers used to hand out over the parts counter. Carrier was perhaps the best known one, but Trane and Goodman made them as well. Nowadays, that info is sometimes published in the unit catalog or selection documents. It's a bit harder to find. either way, it is not unique to any one manufacturer. There is a direct relationship between the cooling in Btu/h, air flow in CFM and delta T that is true for all comfort cooling applications. When it comes to mini splits, VRF, and special applications like CRAC, these numbers are no longer reliable and you need to go to that individual manufacturer for the right specs. Additionally, for the last decade or so, Carrier brands have abandoned the old standard of 400 CFM per ton on their residential split systems in favor of 350 CFM per ton for all but arid climates. This naturally creates a higher Delta T and they will publish this in their literature.
Sir. I have a 3 month old dual fuel heat pump Lennox. In cool mode it runs fine, gas furnace doesn’t trip on high limit but on heat pump mode my pressures sky rocket to 575 psi on both sides with in 15 seconds of runnngs then trips on high limit and gives me an ambient sensor fault. I diagnose it as a faulty/clogged txv but not sure witch on exterior or interior so I’m changing both. Can u help me asap? What would cause those pressures?
This isn't tech support. That would be irresponsible.
Audio only in the left channel. Sorry, cant watch.
If that’s a downflow unit that would be disastrous. I would tell them to turn it completely off you would almost have to babysit it regardless are there going to be a flood and some damage of some sort. The best thing is to have freeze protection so it cannot freeze. As well as low pressure switch etc.😂🎉❤😎👍
Where are the handouts available?
@HVACServiceMentor Is your website down/misconfigured? All I get is a blank screen with a credentials pop-up. I'd love to see what you've got on your site but I can't right now.
site was in transition go to hvactraining.squarespace.com/
At 59:30 do you have a typo in the slide? Isn't the switch normally closed, open on DROP pressure switch? When pressure gets too low, you want the fan to stop so pressure can rise. So you open the switch, which shuts off the fan. Normally, you expect the fan to run at all times, so it is normally closed. Am I understanding it correctly?
Also, as many others have noted in the comments, what happened to your website? It immediately asks for a login, and there is no way to view anything else.
I will look into the video about your question. Website was in transition go to hvactraining.squarespace.com/ (Edit) Good Catch! There is a typo. It should read Normally open, Close on Rise. This switch is normally open. Normal refers to the position of a switch when the unit is at rest. This switch will be open until pressure rises to the cut in point when it will close. While you are correct that the switch will open when pressure falls below the cut out point, standard practice is to consider what switches will do on a rise in the controlled medium. This can get extra confusing with low pressure switches and loss of charge switches. Under normal circumstances, when the unit has normal pressure, these types of switches will be closed at all times. Those switches are often drawn on schematics as normally open because it is the rise of pressure above their setpoint which closes them. If you were to find one in a box and test it, you would find it open. In fact, I've seen those drawn both ways! Great question!
Just spent the last hour trying to figure out why my right speakers and headphone all stopped working. Turns out it’s just this video.
Sorry about that. I'm a better tech than a video producer🙂
Excellent video. Thank you. How do I sign up for free class? It takes me to login but no way to signup. Thanks
site was in transition go to hvactraining.squarespace.com/ click on subscribe
@@hvacservicementor Thank you. Greatly appreciated!
@@rydorien sure thing. I just upload an entire 2.5 hour session of the gas heating boot camp today on RUclips. Let me know what you think if you get a chance to watch it.
Do you do walk in classes?
I mean refrigeration walk inn.
O.M.G.... I tried. But listening to you is like watching paint dry.
No one has forced you to listen.
I tried to go to the website but it asks for login info ...
site was in transition go to hvactraining.squarespace.com/
But the blower is more important because if the air that's going thru the coil isn't enough then it's going to freeze and if it's to much then it won't cool
The blower is responsible for delivering the heat load to the evaporator. It is very important. In three phase units, reverse rotation of a fan motor will create this problem.
@@hvacservicementor
TXV is the elegant solution. In the absence of that, why not adjust the airflow across the evaporator to regulate the heat load? For example, a temperature commanded VFD. Or a 2/3 speed fan motor switching speeds based on inlet air temperature thresholds. Or multiple fans with reverse flow blocking shutters.
Watching in saudi arabia...
More liquid in the system can cause ice.like R22....thats posible...ser thanks..
As Salam Aleykum my brother.
How is work there is busy there 💰 ?
@@Hvacr123 yes ser very busy..and the weather is to hot...
@@alvinobalan2320 yes I heard about it .and also I’d UAE they need good technicians too for good money 💰
Would love to hear what you got to say. But you just talk in circles. Get on with it ! ! ! !
Is it possible for evap to freeze due to being overcharged?
No. You can create all kinds of other problems, though!
Is it possible for evap to freeze due to being overcharged?
Nope overcharging a system alone won't cause it to freeze the evaporator.
Generally, the answer is No. Freezing evaporator is almost always related to heat load at the evap in some way.