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Electric vs. Gas Furnace

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  • Sep 29th, 2008 4:54 pm
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[OP]
Newbie
Nov 5, 2006
41 posts

Electric vs. Gas Furnace

I am thinking of converting my electric forced air furnace into a gas furnace. The electric furnace is still working but I'm wondering how much I can save on energy cost by switching into gas.

It would cost me about $4-5K for the new gas furnace. Is it worth it to convert? If I do covert to gas, how much per month I can save on energy cost? The contractor said I would need a 100,000 BTU furnace for a 3600 sq. ft. home on top of a walkout basement. Pls. help me to make this decision. Thx.
9 replies
Newbie
Jul 26, 2008
84 posts
ottawa
skysky wrote:
Sep 26th, 2008 6:32 pm
I am thinking of converting my electric forced air furnace into a gas furnace. The electric furnace is still working but I'm wondering how much I can save on energy cost by switching into gas.

It would cost me about $4-5K for the new gas furnace. Is it worth it to convert? If I do covert to gas, how much per month I can save on energy cost? The contractor said I would need a 100,000 BTU furnace for a 3600 sq. ft. home on top of a walkout basement. Pls. help me to make this decision. Thx.
I'm not expert but I found CMC site useful for this type of stuff:
check out:

http://www.cmhc-schl.gc.ca/en/co/renoho ... sh_018.cfm
[OP]
Newbie
Nov 5, 2006
41 posts
Thanks Jazzyred for the link.

However, I still can't find an easy answer. Can anyone in the industry or who knows this area well offer me some guidance or estimation?
Member
Dec 10, 2007
324 posts
12 upvotes
How much do you pay monthly for your electric furnace?
[OP]
Newbie
Nov 5, 2006
41 posts
OldFortYork wrote:
Sep 26th, 2008 10:11 pm
How much do you pay monthly for your electric furnace?
Believe it or not, that's a good question as I have just taken possession of this house. I will try to call the hydro company on Monday and find out.
Deal Guru
Aug 2, 2001
13002 posts
3782 upvotes
One thing to consider is, do you have anything else on gas? My gas bill has $30-$40/month in fees (Not related to the gas I use). If I were to get rid of my gas furnace/water heater and move to electric, I would save the $30-40/month in fees. Even if the electric devices were not as efficient, their inefficiencies would still need to be greater than the basic monthly fees.


I would love to here what your electric furnace costs you per month, as when my furnace needs replacement I will be exploring what it costs to get rid of the natural gas appliances altogether.
Deal Addict
User avatar
Mar 8, 2002
3777 posts
581 upvotes
Ottawa
It typically costs two to three times more to heat your home and hot water with electricity than it does with gas.

In the OP's example, for space heating only (excluding hot water):

Ontario (rates are averages including delivery and other charges)
Gas $0.44 /m3 = $12.32 /MMBTU (1 million BTU's)
Electricity $0.13 /kWh = $36.64 /MMBTU

Toronto LBPIA Heating Degree Days (30 yr avg) 7318.8 HDD BASE 65F

3600 sq ft home with 1800 sq ft basement 3600 SQ FT
Average heating need per square foot (contractor guess) 18 BTU

Estimated annual heating load 126.5 MMBTU

Estimated Annual Cost with gas at 80% efficiency $1,947.13
Estimated Annual Cost with gas at 84% efficiency $1,854.41
Estimated Annual Cost with gas at 90% efficiency $1,730.78
Estimated Annual Cost with electricity at 100% efficiency $4,633.24

Estimated annual savings based on 84% efficient gas: $2,778.83

These numbers were based on a fair number of assumptions and for a more accurate estimate you would need a qualified person to do a heating load analysis of your home. But if nothing else, it does give you an idea of the magnitude of the savings available with gas over electric in Ontario. This also shows how spending thousands more on a high efficiency furnace vs a mid efficiency yields very little savings.

One other key point with moving away from electric heating - you won't be subject to increased time-of-day electricity pricing (when it comes into effect in the future) to heat your home.
Deal Addict
User avatar
Mar 8, 2002
3777 posts
581 upvotes
Ottawa
A dollar a cubic meter?!? Man, you are getting ripped off! You must have signed with a marketer or got slammed by one.

44 cents a cubic meter comes from my gas bills, basically take the bill total and divide by monthly consumption in cubic meters. This gives a more realistic picture of the actual cost per cubic meter. The rates that the utilities advertise are for a unit of energy only and do not include all the other charges, like taxes, delivery, debt retirement, minimum customer charge, meter charge, regulatory charges, etc.
Member
User avatar
Mar 24, 2008
366 posts
8 upvotes
MacGyver wrote:
Sep 28th, 2008 9:47 pm
These numbers were based on a fair number of assumptions and for a more accurate estimate you would need a qualified person to do a heating load analysis of your home. But if nothing else, it does give you an idea of the magnitude of the savings available with gas over electric in Ontario. This also shows how spending thousands more on a high efficiency furnace vs a mid efficiency yields very little savings.
That was a very thoughtful post. I hope you don't mind me attempting to clarify one of your assumptions.

1. The price difference between a mid and high efficiency furnace is not "thousands". There is a one thousand dollar difference between a two-stage AC motor mid-efficiency and a two-stage AC motor high efficiency furnace in my price book.

2. I'm can't think of a manufacturer currently making a 84% AFUE furnace. 80% is common and I believe you can still find some 78s.

3. At the two hundred dollar cost difference you suggest, then the "pay-back" of the high efficiency furnace is five years.

4. However, if the homeowner participates in the EcoEnergy rebate program, then a top of the line high efficiency furnace (95% AFUE, DC/ECM motor) is the same cost as the mid I just described.

5. Another benefit of the high effiency furnace is not needing to use inside air for combustion purposes.

6. By Ontario Building Code, mid-efficiency furnaces cannot be installed in new construction. Most people don't want to invest in phased-out technology.

Cheers,
Deal Addict
User avatar
Mar 8, 2002
3777 posts
581 upvotes
Ottawa
I just pulled some efficiency numbers out of a hat. 84% is the maximum efficiency available before you move to a high-efficiency condensing furnace. Switching to high efficiency may not be easy or cheap, not because of the furnace itself, but also because of the venting requirements which have become more stringent in recent years. Also the efficiencies are theoretical maximums, when your furnace is running at part load the efficiencies will not be as good.

In my case I replaced my furnace with a mid efficiency because a high efficiency would require all new venting, which cannot physically be installed in my house without violating several codes and annoying the neighbours with the noise.

If you can get in on the ecoENERGY incentives, then by all means! :)
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