The "quick and dirty" is 500sf per ton of cooling but you really need to do a
manual J survey to get the right number. The number here in Fla is not going to
be the same as in Toronto and a CBS rancher is not going to be the same as a 2
story stick built.
That's why so many people are dissatisfied with their HVAC systems. There
are a lot of hacks out there that still go some "rule of thumb" when it
comes to sizing units. I'll give you an example of my houses:
I lived in my last house for 16 years. It had 1700 square foot of living
space. About 2 years before I moved out of it, I put a new furnace and A/C.
Took all the measurements and popped it into the computer and came out to 3
Tons (alright, it was 2.8 tons). My dad decided to have me replace his 20
yrear old system because he was selling the house (at the time I did not
know I would end up buying it). It is almost 2300 square feet and it took a
2 1/2 ton! (It heats and cools fine I might add).
I know that isn't that big of a difference, but it's just to show you how
different it can be when the two houses are less than 2 miles apart (so it's
the same climate). If i had used the "1 ton per 500 sq ft" method, I'd have
almost a 5 ton in this house!
Ouch. They heat the house air. Maybe you need a dirty AC filter instead,
to send the latent heat outdoors with lower vecocity air in the AC and
more dehumidification. Where does all this humidity come from? Air leaks?
Water leaks? A damp basement floor?
I super insulated the house, and am in total shade on a lake , a tight
house done to double to triple insulation standards. Next will be a
furnace with a VS DC motor so I will be able to drop fan speed and
double humidity removal.
It is an extremely tight super insulated house of 1875 sq ft including
heated basement. Zone 6 , to -15f in the midwest.
Last years total gas bill for heating , hot water and dryer and gas
cooking was 336.50
I just need 1 ton not 2 of AC, I have no leaks so don't second guess
the situation . My yearly gas bill proves it.
And no supplemental heating is used. Buildings can be upgraded for
Did you waste money on excess insulation? You could have spent the same
money on less insulation and a little more energy. What did you
estimate the payback term would be when going from double to triple
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