New Grandaire furnace, gas high efficiency 40k btu in 1200 sft house
near boston. All new insulated duct work, hooked up and seems to run
right, but the air coming out of the supplies is only about 75
degrees. Any ideas why its so cool?
Most probably the furnace wasn't set up right... blower curves, static
pressure, temp rise, manifold pressures and the rest. OTOH, it may be set up
right if the vent air temps were taken and the house was 35 - 45 degrees or
I believe I would be calling the installer back to check it and make sure
that its not just operating, but operating correctly.
The house was about 60 degrees. This is the 3rd heating system this
guy has done for me and I've never had any problem. He's never seen
anything like this so I wondering if anyone else has.
Like I said.... its not set up correctly. Assuming a 90+ furnace, you should
have a 30 - 60F temp rise, .10wc or less static pressure, around 800 -
850cfm blower speed(depending on temp rise), and your manifold pressure will
be dependant on if your on nat gas or propane. Your not getting anywhere
near what your supposed to.... its not set up or adjusted correctly. If your
installer can't figure this out, you need another installer.
Is the burner cycling on and off as the blower runs continuously? If
so, depending on the model, that could indicate airflow is too low.
Hmmm, but then the outlet air should be hot! Doesn't make sense.
40K BTU sounds maybe a bit low, but depends on the actual heat loss of
Could be something in the gas valve is set wrong, and you are not
getting the correct gas flow.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.