Thread: My new project
View Single Post
Old 04-21-13, 12:10 PM   #95
Supreme EcoRenovator
AC_Hacker's Avatar
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,002
Thanks: 303
Thanked 712 Times in 532 Posts

Originally Posted by AC_Hacker View Post
Is this really true?

What is the price of electricity in your area, and what is the price of gas in your area?

Did you try the BuildItSolar Fuel Calculator? You can plug in your local values...

I'd be very interested to know your results.


OK, since S-F won't talk to me, I did my best to look up the prices from 3500 miles away...

FROM THIS LINK it looks like electricity is:

7.314/kWh = $0.07314/kWh

FROM THIS LINK it looks like gas price per therm is:


I don't know what S-F's Heat Pump HSPF might be, but my older heat pump has a HSPF of:

7.7 (really, not so good)

COP = HSPF/3.412, so...

COP = 7.7/3.412 = 2.26 (that's pretty low for today's mini-splits).

I'll assume that S-F's gas heat is 95% efficient (I'd be surprised if it was higher).

...and using BUILD-IT-SOLAR's FUEL_COMPARISON_CALCULATOR, I am getting the result that to provide 100,000 BTUs of heat would require:

NAT GAS: $1.40/100,000 BTUs

HEAT PUMP: $0.95/100,000 BTUs

So, it looks like the heat pumps would be a lot cheaper to run... like about 68% as expensive.

But, if we look at the environmental damage caused by CO2:

NAT GAS: 12.63 pounds of CO2 per 100,000 BTUs of heat

HEAT PUMP: 18.14 pounds of CO2 per 100,000 BTUs of heat

That would be the coal fired plants doing their work....

Looking at it this way, it looks like the heat pumps would actually increase the probability that Xringer's grand children would suffer from Asthma.

I guess that more and more insulation really is the best alternative...

I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote