I have some questions about the sizing of the HVAC system our installer is planning to install in about 10 days.
We have a 2200 sq.ft., 2 story bungalow in the S.F.Bay Area, the lower half is new & under construction, no existing ductwork.
I ran the HVAC-Calc program & with these results:
Sensible Heat Gain: 28,631
Latent Heat Gain: 959
Total Heat Gain: 25,590
Total Heat Loss: 23,551 [28,261 with 20% safety factor]
Summer temp. 72
Winter temp. 72
Relative Humidity 50
Summer temp. 82
Winter temp. 36
Summer grains of moisture 59
Daily temp. range: Medium
Were looking at a Carrier Infinity 96 system. The installer wants to put in a 60,000BTU furnace, with a blower capable of about 1,050CFM, claiming that with the 2 stage burner & variable speed blower, it will be fine.
This looks like double the furnace the HVAC-Calc. would suggest, no? Wouldn't that give us short cycle times, & decreased efficiency & comfort? I really want to maximize efficeny, not to mention comfort.
The installer, using his rule-of-thumb sizing [never heard of Manual J], does not inspire confidence, but, due to a heat wave here 2 weeks ago, all the good HVAC pros are booked for over a month. [Our contractor needs to sheetrock over the ducts in ~2 weeks.]
So, I'm depending on you Pros to help us avoid installing an expensive & poorly designed system.
As far as AC [which we'll need only 20-30 days/year], he's planning a 2 ton system.
I mentioned my HVAC-Calc results to "Mr. No-J", and he said that the smaller 40,000BTU sytem has a larger cabinet, which may not fit in our available space. Does it come in a 30,000BTU size?
So, thanks in advance for any help you can offer!