So just had a Brand new Goodman furnace and a/c installed before winter hit. As soon as heating season started i noticed it was short cycling and had a flash code of 4. I contacted the installer and he did a few things. 1. increased blower speed. 2. Said it was not getting enough return air and cut a large vent into ducting right before filter. #3. Turned gas pressure down. It was no longer overheating but the air coming out did not even get the ducting warm. It would take forever to warm the house enough for furnace to turn off. I verified all ducts are open supply and return. Filter is brand new. I checked gas pressure and he had it adjusted to 1.50 where manufacturers spec is 3.50. I adjusted it back up to 3.50 but again after 5 minutes it would turn off and flash code would turn on. I adjusted it back down to 2.50 and at that pressure it does not overheat anymore but it bothers me that the gas pressure would need to be turned down. It should operate at 3.50 for best efficiency as that is what manufacturer wants it set at. What do i need to look at to figure out why my furnace overheats when gas pressure is set to its optimal pressure? Any insight would be appreciated!!
Goodman Furnace short cycling because of high limit . Cant figure out why
hvac
Best Answer
How many square feet is your house? When was it built? And where do you live? You should never alter the gas pressure from 3.5 inch water column. It has more to do with the flame speed then the capacity. If the pressure is too low then your flame will ride on the burner faces and destroy them. NG burns at about 12" per second and 3.5 inch NG comes out of the orifices at about 12" per second. Without the requested information above answering your question is essentially impossible. Duct size may be an issue, but it's more complicated then it's 8x24. Also if you have air conditioning make sure the evaporator is clean.