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-   -   Should i go from GAS to Total Electric HVAC & Water heater? (http://www.diychatroom.com/f17/should-i-go-gas-total-electric-hvac-water-heater-41762/)

ehoez 04-03-2009 09:47 PM

Should i go from GAS to Total Electric HVAC & Water heater?
 
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.

kenmac 04-03-2009 09:57 PM

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

Yoyizit 04-03-2009 11:11 PM

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.

Home Air Direct 04-03-2009 11:14 PM

: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.

Good luck.
Jay

beenthere 04-03-2009 11:27 PM

As othrs said. A heat pump would save you money.
But, just regular electric resistance heat would cost you more then gas.

But. Based on that gas bill.
You should first do some improvements to your home.
Seal it up. Add insulation.

Home Air Direct 04-03-2009 11:34 PM

:thumbsup: Insulate.

You can't spend too much on insulation. It pays you back.

beenthere 04-04-2009 06:11 AM

Quote:

Originally Posted by Home Air Direct (Post 254770)
:thumbsup: Insulate.

You can't spend too much on insulation. It pays you back.

While adding insulation is always a good idea.

First work on lowering infiltration(hard to caulk around plates in the attic after you blow insulation in).

yuri 04-04-2009 09:50 AM

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.

beenthere 04-04-2009 11:15 AM

Best to use them while doing a blower door test.

Will show even more yet.

A lot of people have no idea how much they pay to have recessed lights, in the way of energy waste.

If people knew how unsealed the inside wall plates in the attics are.
They would flip out. Specially the cavities that are being used as return ducts.

myhvachelp 04-06-2009 09:57 AM

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 35F 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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