Delta T’s and Blower Speeds.. HVAC Service Call
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- Опубликовано: 1 окт 2024
- In this video we do a quality inspection on a system that was just installed. After checking the Delta T something is wrong. Watch and learn what we do to get the system cooling properly. Enjoy
I would recommend using static and the units CFM chart to set blower speed. Delta-T will vary based on humidity in the home. Match the cfm’s to the tons of the coil to push the correct amount of air. 350-450cfm per ton.
the video is interesting but when I see the pressure in the suction line that is over 140 psi I would also be contemplating the possibility that the compressor may have a valve problem because something that I have been able to verify is that in the machines that claim to be from high efficiency is only theory because on the nameplate of the condenser they put that it is 30,000 BTU or 2.5 TR and the compressor is 22,000 BTU where the missing 8,000 BTU are and in a period of time the compressor is making a great effort and as a result it is that low pressure so high and there it may be showing valve problems and as we can find out, it is easy to run the freon in the machine and if when picking it up the machine does not go on the blue clock to empty and stays at 70 or 50 psig does not collect more and then we realize that the compressor is not doing it. and to check the speed of the evaporator fan motor is important because if inside the pressures.
I had the same problem yesterday. After installing 1.5 ton unit (410a with a piston) in a 2 bedroom condo my suction line was 150psi and my line temperature was 76F. I realized that I forgot to adjust the fan speed (9-speed variable Goodman motor) the default was set to 1330cfm. I only needed 600cfm...
Wow. Thanks for the information 👍
Fantastic demonstration of this. I didn't know it could be this drastic. I would usually only pull down the speed if the customer complains of high humidity. This is a killer thing to know. Thanks!
No it'll dehumidify.
That was the problem with my setup. Mine was purposely "mismatched" as in 3.5T coil and condenser and 4 ton AH. Only got a 13 delta T at best. I switched the black wire (high speed) to the blue wire (med-high speed) and the delta T went up to around 17. Mine is a piston, not a TXV. At least it's removing humidity now!
Great lesson on how blower speed affects the system!!
I've got a 5ton deltaT at 15 blower speed down to 1575 in a 2100 Sq ft home.When it's hot and a load home doesn't cool.If I speed up blower deltaT going get even lower.Subcooling is good superheat is good.Im thinking high static is main issue but evap could be starving.What do yall think
Thanks a lot for the information
What a super nice guy. You’re my kinda people!
Great video 👍🏻 keep them videos coming stay safe out there
so what range of numbers is considered a good delta t, or does that vary on the system?
Awesome video an great information ....Thank You.
Great follow up. Keep the customer happy. Gold star for you. Thanks for the vids.
Wow great insight. Im rather new and this really gives me alot of valuable info
Do you check static pressure with air flow chart from manufacturer
Really good vid and that's often overlooked. Thanks for a well done video.
Nice troubleshooting and paying attention to the pressures. Good tip about checking the fan speed setting.
Where is the trap for the coil? Is withing the 3 to 6 ft.?
@@carlgibson593 Manual says different.
@@carlgibson593 First of all I just asked a question. Then gave you an answer due to manual instructions. Every manual for the past 25 years of my career states installing p traps whether on air handlers or Evap coils. the manual supersedes local codes. due to your great video taking I can't see the model number on the coil. But i suspect it is an ADP Cased coil. Having a p trap With a clean out tee that is capped and the trap filled with water prevents cool air escaping from the system. And you know that we don't want any air loss. Plus putting in a breather Tee right after the trap helps with draining due to droops that maybe in the condensate line. that may not be properly supported. Am I being superior? No. its experience bub, You should learn to appreciate it!
@@carlgibson593 Now your getting nasty!
Good job man! very good information 👍🏼
Thanks for sharing..God bless
I have the same problem at my house where my DT is 13* and my Job Link Probes tell me the blower speed is too high but how can I find a lower speed if I have a Variable Speed motor, mess with the Dip Switches??
Possibly but you can’t always go by the job link app. Anytime the delta t is low it will always say the blower speed it high when it’s potentially a different issue. What is your SH and SC?
@@HVACTechTips My SC is at 8* (it calls for a 7.5* per specs) and my SH is at 12*. txv system. Now at that time of checking the relative humidity was at 55 to 60% since I live close to Gulf of Mx.
@@juanrobles9511 it really depends on a lot of things. Enough return? No vents closed? Low load in the house? Your blower may be set to a higher tonnage. You would have to check the dip switch settings on the back of the furnace door and match to the condenser tonnage to the switches on the board. If it doesn’t have dip switches it will have speed taps on the top of the blower motor where you can adjust speeds
What is the delta T
goodjob bro
Thanks again for the great info
I just have a hard time understanding when to speed up or slow down blower speed according to delta T any simple way to go by it?
You should always start with the manufacture specs. You can usually find it on the door or schematic. If you have a low delta t raise speeds, if you have a high delta t, lower speeds
This is backwards
@@joshuameadows5574 I was thinking the same thing
Facts! Thanks man
Great video
Slamming? Is that an industry term? Talk actually industry terms.
You mama slamming these nnnts. 😅
Will Variable speed Blower Motor affect your delta T?
It can. But if the system is sized correct, it should keep a good delta t