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Force air gas furnace - repair or replace

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  • Nov 28th, 2019 12:50 am
[OP]
Jr. Member
Jan 11, 2007
128 posts
30 upvotes

Force air gas furnace - repair or replace

My 23-year old Lennox gas furnace had a service and check up this week. The repairman said the heat exchanger shows signs of rust and should be replaced. He said that because of its age, getting parts is difficult and would be around $3,000. He suggested a replacement, and take advantage of the rebate available from Fortis. However, the quotes that they provided even the cheapest is close to $7K (with tax and installation, but before rebate), and the high end one (which he is pushing for) is close to $8K. All quotes are for Lennox.

My question are:
- is 23-year old furnace that old and not worth fixing? I am no expert, but have been to houses with much older furnace
- what is the price range of gas furnace replacement? I'm no reference to see if the quotes are in the right ball park.
8 replies
Deal Expert
User avatar
Feb 11, 2007
19448 posts
22565 upvotes
GTA
DealMarker wrote: My 23-year old Lennox gas furnace had a service and check up this week. The repairman said the heat exchanger shows signs of rust and should be replaced. He said that because of its age, getting parts is difficult and would be around $3,000. He suggested a replacement, and take advantage of the rebate available from Fortis. However, the quotes that they provided even the cheapest is close to $7K (with tax and installation, but before rebate), and the high end one (which he is pushing for) is close to $8K. All quotes are for Lennox.

My question are:
- is 23-year old furnace that old and not worth fixing? I am no expert, but have been to houses with much older furnace
- what is the price range of gas furnace replacement? I'm no reference to see if the quotes are in the right ball park.
New furnace is a good idea at that age. You should be able to get one for $3-5k, don't forget rebates. Contact Craig at https://www.fourseasoncomfort.com/ He's the RFD recommended HVAC guy.
If the women don't find you handsome, they should at least find you handy.
Deal Fanatic
Jul 7, 2017
8353 posts
4064 upvotes
SW corner of the cou…
This guy's probably out west with Fortis as a NG provider.

FWIW, the older (especially 50-55% efficiency) furnaces are much more durable than HE or even 80% efficient ones Unfortunately they also send a lot of heat up the chimney.
I smile when I see container ships sailing past my house laden with stuff made in China
Deal Addict
Jun 16, 2009
3788 posts
2327 upvotes
Woodbridge
Which province / city do you reside in ? Furnace price is tooooo steep ( 7K) if you are in GTA.
I am not a big risk taker, so will never have a very old furnace in home. If you have to chnage the furnace anyways in the near future than why not start reaping the benefits RIGHT NOW?
Newer furnaces are much more complicated with tonnes of electronics to get the best efficiency, safety features. It will be unwise to compare it with old models for reliability.
DealMarker wrote: My 23-year old Lennox gas furnace had a service and check up this week. The repairman said the heat exchanger shows signs of rust and should be replaced. He said that because of its age, getting parts is difficult and would be around $3,000. He suggested a replacement, and take advantage of the rebate available from Fortis. However, the quotes that they provided even the cheapest is close to $7K (with tax and installation, but before rebate), and the high end one (which he is pushing for) is close to $8K. All quotes are for Lennox.

My question are:
- is 23-year old furnace that old and not worth fixing? I am no expert, but have been to houses with much older furnace
- what is the price range of gas furnace replacement? I'm no reference to see if the quotes are in the right ball park.
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[OP]
Jr. Member
Jan 11, 2007
128 posts
30 upvotes
Yes, I'm in Vancouver.

Just did a quick check, my existing furnace is 80% efficiency.
Deal Fanatic
Jul 7, 2017
8353 posts
4064 upvotes
SW corner of the cou…
You might want to get the furnace model number and start searching for parts. Have no idea whether a heat exchanger is easy/not time consuming to replace or not.

At any rate, these things will show signs of rust. Just natural given it's metal (iron) and it's exposed to heat. I think what matters is whether it has corroded through or is coming close.
I smile when I see container ships sailing past my house laden with stuff made in China
Deal Expert
User avatar
Feb 11, 2007
19448 posts
22565 upvotes
GTA
Signs of rust sounds like not much rust. He would say completely rusted out if it was that bad.

Plus, since you are in Vancouver, you likely won't use it much anyhow, and could use a space heater if the furnace did give out.
If the women don't find you handsome, they should at least find you handy.
Deal Fanatic
Dec 12, 2009
5429 posts
2923 upvotes
Toronto
engineered wrote: Signs of rust sounds like not much rust. He would say completely rusted out if it was that bad.
Or would have red tagged it if really bad.

@DealMarker it sounds like you have time to do your research on furnaces and local costs. Do that.
Once you have a idea of replacement costs, you can compare that to repair costs and the age.
At some point of time, it just makes sense to replace the furnace. e.g. the cost of repair is 1/2 the cost of new (pick your number)
A new one typically comes with a 5 or 10 year or longer warranty. That means you will have a reprieve from repairs for a while.

Likely you will need a new A/C about the same time as the furnace or a few years afterwards. You may as well price that out as well. Try for a package deal.
A/C efficiencies have improved in 25 years.
Deal Expert
Jan 27, 2006
20527 posts
13917 upvotes
Vancouver, BC
DealMarker wrote: Yes, I'm in Vancouver.

Just did a quick check, my existing furnace is 80% efficiency.
Sounds like you have the same generation furnace as the one I'm currently running - a Whisperheat.
engineered wrote: Signs of rust sounds like not much rust. He would say completely rusted out if it was that bad.

Plus, since you are in Vancouver, you likely won't use it much anyhow, and could use a space heater if the furnace did give out.
I'm thinking that the service person was really out to try to get a sale on a new furnace rather than giving an honest opinion on the furnace.

All NG forced-air furnaces will have some degree of rust as the combustion process produces water as well as some other byproducts which are slightly corrosive. While heat exchangers are typically coated with a corrosion-resistant coating, the constant heating and cooling of the heat exchanger may cause some cracks in those coatings creating openings for corrosion to happen. Rust in heat exchangers is only a problem IF the heat exchanger is cracked all the way through the metal allowing combustion gases to mix in with the heated air - ie a carbon monoxide issue. A couple of good carbon monoxide sensors should help warn you if there is a problem.

As for parts, OP, don't let the repair guy scare you. Since I've owned the furnace, I have had no issues in obtaining parts and doing the work myself - replaced the ignitor circuit as well as the furnace fan motor. These furnaces are pretty simple things compared to the newer furnaces.

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