I just bought a 30+ yr old home, it has a fully working, (ORGINAL 1970 era) Natural gas furnace, and AC unit, both works FINE.. nothing wrong.. (we'll i did have to replace the thermocoupler last week, but now works fine)..
I wanted to know what you guys think..
I Live in Atlanta GA, not too cold, but can hit low 30s everynow and then for about 2months out of the year.
Home is aprox 1500sf
Should i go Total electric?
Gas bill in Jan was $250s
Electric bill was only $70.
Electric is 7.9cents per KwH here..
Gas is 89cents per therm (/w 12month lock) for 2009 (but $30 per month, base charge)
Gas was $1.19 per therm for 2008
just having the gas turned off would save $30 a month.
I'am in lower al & it gets cold here.. You could go either way. If you update your gas equip. it would save . You may want to check elec. rates vs gas in your area.. Elec heat pump with back up gas or back up heat strips. Keep in mind if & when the heat strips come . They use alot of elec. Like I said check the rates in your area for both
A therm = $0.89 worth of gas = 29.3 kwh = $2.34 worth of elec.
$250 gas bill = 281 therms = 8230 kwh = $658
but you need to know the COP of the heat pump if you get one.
Almost all of the $70 in elec. usage also went into heating your house.
:thumbsup: Yeah, what Kenmac said. You are in prime heat pump country. You should be able to get an 80% gas furnace for the same $ as an air handler as your back-up. Personally I would ramp it up a little and get the extra 13-14% gain of efficiency and get a no frills 93% gas furnace as the back-up. I wouldn't waste my money and get any bells or whistles in the furnace, as it really will not pay off, as a secondary heat source. (exception, is if you are trying take advantage of tax credit). Throw a Honeywell 8320U1008 stat coupled with a C7089U1006 outdoor temp sensor to act as your dual fuel kit and you should be good to go.
Then, you have the best of both worlds. I have rarely seen an area where elec. heat strips were ever as efficient as gas at any price. 32-45 degree nights are what the HP was built for, and you have a bunch of those to take advantage of.
What do you guys think about those infra red scans of a home before doing the insulation. I watch This Old House hour and they did one. It was shocking to see how much loss there is around light fixtures/bathroom exhaust fans and anywhere the ceiling is perforated. I think it would be worth the money to know where the worst leaks are.
ehoez/OP may need to add a erv/hrv to get some ventilation in his house if he seals it up airtight. Right now the old chimney is doing that for him.
As a ballpark on comparing the costs of 1 million btu's of heat for gas furnace and heat pump, here are some calculations:
Gas at $1.19 per therm, 70% efficient furnace (a guess on what yours is now):
(1,000,000 / 100,000 BTU per therm) x 1.19 / .70
= $17.00
Gas at $1.19 per therm, 80% efficient furnace:
(1,000,000 / 100,000 BTU per therm) x 1.19 / .80
= $14.88
Gas at $1.19 per therm, 92% efficient furnace:
(1,000,000 / 100,000 BTU per therm) x 1.19 / .92
= $12.93
Heat pump w/electricity at 7.9 cents per KWH, average C.O.P. = 3.25 at 35°F ambient:
(1,000,000 / 3414 btu per KWH) x .079 / 3.25
= $7.12
It looks like an HP will save quite a bit on operation, but without knowing your local install costs its hard to say how long a payback it will be. You could consider keeping your existing furnace as backup instead of investing in a new furnace, or heat strips, you may not use that much.
Yes, tightening your thermal envelope is never wasted money. A blower door and thermal imaging test will help find the low hanging fruit/high return areas to focus on.
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