HVAC Troubleshooting | Low (and Strange) Delta T Issues
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- Опубліковано 24 сер 2024
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Never seen either of these scenarios because I live in basement furnace land
I've run into those Goodman air handlers with stuck sequencer energizing the heat strips while running in AC. 10 degree delta. Stuck the amprobe on the strips and sure enough, heating and cooling simultaneously. Ended up just replacing the entire strip kit since everything was rusty from previous water damage.
I just had a job that had 12degrees delta t. The pressures were slightly low liquid line(260psi), slightly high suction (170 psi). Outdoor ambient was abour 90 degrees. System was only about 6 months old. It was the compressor. I replaced the compressor and everything worked perfectly after that.
3 degree Delta, unit overcharged, 20 pounds of refrigerant stuffed into a unit designed for 8 pounds. Recovered and worked fine. And got to resale the refrigerant taken out.
2 degrees delt. Blower door off, with door switch bypassed. Pulling in 125 degree attic heat.Customer changed filter and left door off. .
If I ever wrote a book on hvac , I could have several chapters on issues caused by installers and customers. . But both blame the equipment as being junk.
First scenario is a similar issue I found with my older GE refrigerator, defrost element was turning on during normal cooling operation, result of a badly worn mechanical defrost timer. Compressor was running constantly to maintain temperature with a spotlessly clean condenser coil. A few minutes of laying on the floor with a DVM, and the unwanted assistance of my black cat, found the problem.
Used to be a fairly common problem with GE refrigerators. Defrost heaters working as hard as the compressor lol
Good tips. I have encountered both cases a couple of times.
All of this is very true. Heading out to one today that is a bit of a head scratcher. It will be part of my video today.
5 degree delta. 4 inch gap between air handler and return plenum under side of unit. Also evap totally blocked with insulation and rat nest .
ALWAYS measure Delta T at the air handler, or at least return air temp
I had a similar problem. I have a 2 year old York and the supply was blowing 115 F the other week with the AC set to 74. My upstairs zone valve in my oil boiler was open even though the Sensi thermostat was set to AC and the log showed no heat called for the last month. I closed the furnace ball valve and it went down to 54 F on the supply. Now I am still having a problem. At night when the outside air is 80F the upstairs air handler in the attic blows out 54F but during the day when it is 90F (and attic is over 110) it blows out 63F. I changed filters and cleaned the outside condenser with no change.
Very informative! 😁👍🔥
I will be replacing a failing condenser fan motor on an older Trane 410A residential unit.
High superheat and 11° Delta T on a piston operated coil.
When spun by hand, the fan only completes a few rotations. Amp draw is well below its rating even with the bad bearings.
Great tips, thanks, Zack!
I had a scenario last night. Im in NC. 10 degree delta t. Ambient temp 92. Low humidity outside. Pressures 132/317. 13 sh. 2 sc. Comp amps 6. FLA 12.8. I slowed the fan speed down to med. high. added a 1lbs of 410 pressures didnt change and delta t went to 12-13. Im thinking the txv is starting to go bad.
Thanks for let us know this nice experience from u, thanks again for
Yep 4 degree Delta. Heat strips running in the middle of August. WTF.
Would you recommend insulating the outside portion of the air handler if it's in the attic?
Delt of 4 degrees, Superheat 50 degrees, Furnance running in middle of summer right after maintenance done. Low voltage wires touching in attic.
Delt of 2 degrees, Return open to 130 degree attic. due to blown out return, bad duct work.
When this happens, you need to bring in the Delta Force 😆
Maybe check everything visually before putting guages on and saying it's working perfectly
👍
Dirty inside coil
I wish to be excluded from giveaways. When we had the add-on AC installed in our mobile home, the installer failed to check the function of the furnace. Oops. I checked the furnace one before it was cold enough to need it. The thermostat was calling for heat and cooling at the same time in heating mode. I called the same company that installed the AC to fix the issue. They billed for the changout of the thermostat. I think they should have ate that cost considering the installer didn't test the furnace in the first place.
ALWAYS measure Delta T at the air handler, or at least return air temp