Thread: HVAC Heat Pump
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Old 03-10-2024, 08:00 PM   #3 (permalink)
redpoint5
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Quote:
Originally Posted by freebeard View Post
It's like deja vu all over again.

That's the first thing I remember you posting on the forum.
Well, I joined in 2010, and bought this house in 2019, so there was 9 years of yammering about other things.

First thing I remember posting was a physics question regarding hill climbing. All engine efficiency and aero factors aside, is it more efficient to go faster up a hill. It takes a minimum amount of fuel burn to merely maintain position on a hill, and doing so would be 0% efficient. So you've got to burn the minimum plus something to go up it. The faster the hill is overcome, the less minimum fuel burn is needed. The analogy I gave was a rocket hovering, vs barely gaining altitude, vs going as fast as it can.

I spent too much time estimating how many BTUs I use for heating, converting that to therms, calculating my heating gas bill based on that, figuring out how many kWh I'd use if I heated with a 10 HSPF inverting heat pump... my estimate is I would save between $0-$100 per year. Very tricky converting between all these units. The SEER and HSPF should be simple % efficiency ratings (like a gas furnace) so the math is easy.

Anyhow, I estimated my furnace is on 6% of the year based on my blower on time, which amounts to 657 total heating therms. I also looked at my monthly gas bills, and knowing I have zero heating in July, Aug, Sept, I was able to roughly determine I use 20 therms/mo in hot water, range, dryer. Subtracting that from the total for last year, it comes to 665 therms used for heating.

I pay about $865/yr to heat on 80% efficiency gas. I estimate $790 heating on an inverting heat pump.
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Last edited by redpoint5; 03-10-2024 at 08:10 PM..
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