quote:

Originally posted by jigray3:
If these new units last 12ish years and they cost $12K to install, give or take, they cost essentially $1000/year.

Damn, I'm in the wrong business.

And you need to be saving more than $83/mo on power bills to make it "worth it" rather than running an older unit longer.

And that is just to 'break even', cuz you'd need to start over in 12 years.

quote:

Originally posted by Stlhead:
Your math is pretty close if you are using resistance heat. You are missing the 8% - 10% efficiency loss of the gas furnace, and the efficiency gain of the heat pump. You get about 2.5 times the heat from a heat pump as you put in in electricity. With those energy rates I would estimate that the actual numbers for heat pump vs gas furnace are $1.35 for gas and $1.85 for a heat pump. Note that your climate and your equipment selection can change these figures, along with energy cost changes. You guys get robbed for energy in your beck of the woods.

I’m good with that.... the gas furnace was cheaper than a heat pump would have been in equipment cost. I don’t know why electric rates are high here... and ours is much lower than other very nearby cities because we get our power from a irrigation district. PGE electric rates are supposed to be MUCH higher.

quote:

Originally posted by thumperfbc:

As I understand it 1 therm is approximately the same as 30 kWh, correct? According to my last bills each KWH cost me $0.16 and each therm of NG cost me $1.24. $0.16x30 = $4.80 for an equivalent amount of energy. The electric rate will go up in the summer too, though won’t be using the heater then.

Therm is 100,000 Btu
KW is 3,413 Btu, so times by 29.29 to get a Therm

Using .16 cents for electric and 1.24 for natural, here's the numbers:

All per 100K Btu

Straight electric 4.68

HP with varying COPs:
As the temperature drops, so does the efficiency.
(2.0 being at 0 degrees F)

3.6 1.30
3.3 1.42
3.0 1.56
2.5 1.87
2.2 2.13
2.0 2.34

Natural Gas:

80% 1.51
90% 1.34
92% 1.31
96% 1.26

Looking at your local rates, I'd recommend a 95-96%, two-stage, variable speed, gas-fired furnace and straight A/C.

P.S. When the time comes that equipment only last 12 yrs., I'll hang my hat and retire. And I don't expect that to happen anytime soon.