cobia13
Oct 5, 2007, 04:57 PM
Is there any rule of thumb about the size of a a/c return duct? I cannot get my house below 78 degrees when it is 90+ outside. Even when the house gets to 75 the thermostat will not turn off the unit. I have to dial in a higher number (78).
Thks
cobia13
hvac1000
Oct 5, 2007, 05:51 PM
((I cannot get my house below 78 degrees when it is 90+))
First check the air filter to make sure it is clean.
((even when the house gets to 75 the thermostat will not turn off the unit. I have to dial in a higher number (78).))
Sounds like your thermostat is out of calibration.
((is there any rule of thumb about the size of a a/c return duct?))
Yes there is but it is definitely not the way to correctly calculate the proper size.