| Temps:
OK, I measured some temps around 6:30pm this evening, after the unit was running for 1 hour plus. The thermostat was set at 72 deg.
Outside temp: 69 deg.
Outside hot air exhaust: 80 deg (right above fan)
Inside house temp, first floor: 69 deg
Inside house temp, middle floor: 71-72 deg (near thermostat)
Inside house temp, upper floor: 76 deg
Return air temp: 70 deg (right at furnace filter)
Discharge air temp: 51 deg (right above A-coil)
Discharge air temp at various house vents: 55-56 deg
It seems the temp differentials are fairly normal? So that means the AC is working OK?
Also, I do have a powered attic fan that is on a thermostat. I've played with the temperature settings on that (anywhere from about 90 to 120 or so) and it hasn't seemed to make much actual difference.
Ductwork:
I know there are 5" ducts to all the lower floor vents (I can see these in the basement). I understand 6" or 8" are more common?
But the vents to the upper part of the house must all run off the one rectangular vent (8 x 23) that goes up thru the walls and across the garage ceiling. (I have 2 bedrms above garage) I can't tell what size ductwork runs off of that and down to the individual vents in each room. (Although I would assume it is the same as the basement). That ductwork is all enclosed in the ceilings/walls and I can't get to it to inspect it. I did pull one vent cover off the large 8 x 23 duct in the basement, and checked it with a flashlight, I couldn't see any sign of obstruction or blockages.
Contractors:
The furnace was put in just before we bought the house, 2 yrs ago, so I have no idea about that. Seeing what I am seeing now, I am afraid the previous owners put in the cheapest new furnace they could just to sell the house, or the contractor undersized the unit drastically? Could the blower not be sized correctly to deal with all the backpressure from the ductwork? The strange thing is that I don't remember having a problem heating the house the last couple yrs. (although it could be because heat rises to the upper levels?)
With the AC contractor, he's been out a few times, and says the AC seems to be working OK. He's not sure about the airflow, if that's the problem or not. He has NOT done any load calcs, etc... though. To tell you the truth I'd rather find the problem myself and then determine the best course of action (fixing it myself or going back to a contractor, etc...).
Is there any chance, if it is the blower, that I could get a more powerful blower that will swap right into the same furnace? I've googled the part number on the blower but didn't find a whole lot of info (other than direct replacements)
Thanks everyone so far, your input has been very helpful to me.  |