Underperforming Heat Pump - http://www.hvacmechanic.com/ Forums
Original message
| gettin hot
 |  "Underperforming Heat Pump"
, posted Mon 9 Jun 14:13:  
I have a 5 ton Bryant heat pump that just hasn't been it's old self lately. The compressor and TXV were replaced last fall. Seemed to do OK during winter, but this spring coil began freezing up in AC mode. Tech comes out and sees low suct pressure and immediately adds freon. Schrader valve is leaking too so he replaces core. Coil still freezes up, mainly at night. Comes back out and replaces TXV. Suction pressure is still low and coil still freezes. He is stumped now. I ask about airflow and sure enough turns out the insulation in the air handler is coming loose and needs to be secured. Air flows are now back in the 400 CFM/ton range. He says "let's let it run a couple of days and see how it works. You might have a cap tube plugged."
Being an engineer and tired of techs guessing, I've taken a few measurements. Based on these, what should I expect him to do or look for when he comes back out.
Outdoor amb 87F, WB 77F, Suct 65psi/48.5F (11.5 superheat), Disch 241psi/88F (27 subcooling), Indoor return air 72F, WB 60F, Supply 58.6F, WB 51F, liquid line temp @TXV inlet 89.6F, TXV outlet 89.3F, Evap disch line temp 49F. Liquid line sight glass clear and dry.
Equip documentation says target subcooling should be around 12F at these conditions. Refrigerant overcharge or something else?
Thanks
[this message was edited by gettin hot on Tue 10 Jun 21:41] |
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| geo fan
| "Re(1):Underperforming Heat Pump" , posted Wed 11 Jun 21:19
you only replaced the compessor your pressures indicate to me an absolutly filthy evaporator coil which is probly incased in the ductwork and they probly recomended replacing that when your condenser went and probly difficult to accsess but if all my assumptions are correct it would be worth it to do what it takes to check
ps being a tech im sick of nonothing pencil pushers wondering why everingthing isnt hunkydory when they beg for the cheapest way instead of the best way
ctd2b
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