Restoring an old furnace

[Inventive1]

I'm interested in installing a furnace in my garage. Natural gas is available, and is said to be the cheapest fuel. I had some HVAC experience, but have been away from that business for 25+ years. (Much of that knowledge has been forgotten!)

Back when I worked in HVAC, the systems were relatively simple and easy to understand. Recently, a family member asked me to repair her 6 year old high efficiency heat pump. That unit had a variable speed fan, it was computer controlled, etc. I was surprised how complicated her system was to service. The price of the fan motor was also shockingly high.

This experience made me wonder if it might be better to find an older furnace and install it in the garage instead of a new furnace. I performed an internet search on restoring old furnaces and found nothing. So perhaps this is just a bad idea. What would be the advantages and disadvantages of an old furnace?

 

[danski0224]

Parts availability and cost.

 

[gahrajmahal]

When we had ours replaced a few years ago I asked the repairmen to leave the old one, duct work and packing materials so we could recycle everything. They knocked a few dollars off cause they didn’t have to clean up much. Often with old appliances I repurpose some components and save a few clean sheet metal panels for projects around the garage. The old furnace was working fine when we replaced it so I carefully removed the individual components, listed them on Craigslist and sold most of them. The repairmen said my heat exchanger even looked good and could be used as a spare. At the time our guy said not to replace the central air conditioner if it was working ok as it checked out ok. It’s been about five years since and this marks around 30 years since it was originally installed.

 

[billconner]

I think you can find a new simple one and it will be much more efficient.

 

[Wheelingit]

I wouldn't try to re-use and old heater. Get a basic new unit. One without all the whistles and bells.

 

[fitter30]

Just buy a builders grade.

 

[kaymccampbell]

Unless it's a nearly new takeoff, you don't want a used gas furnace. The heat exchangers perforate after a while, and will give you a free dose of monoxide.

 

[engineer2]

Agree most of the old furnaces are simple and many use standardized parts except for the circuit board. They are plentiful on the used market. Just look up the model number ahead of time to see if it might have issues. I would avoid old ones with a standing pilot light and troublesome older high-efficiency units. That puts you into the 1990's age-wise.

I got a free Williams wall furnace that was going to be thrown out. It needed a $20 thermocouple magnet. It's been good for 20 years so far.
You can also get a new ceiling-hung gas heater for a reasonable price.

 

[Jim greengo]

Depends on your definition of an old furnace.
Heat exchanger is the biggest thing that would worry me,anything else is easily replaced.

 

[38 Dodge Coupe]

I considered doing the same thing. My dad was a heating and refrigeration tech and knew his way around installations and he put the old house furnace in his garage. It worked great but it did take up some real estate on the floor. Years ago when I added a heater to my garage I elected to go with a new unit that suspended from the ceiling. Although it did cost more at the time, I have been pleased with the unit. (40,000 BTU natural gas from Menards) I insulated the garage and it is quite comfortable. A side benefit is that it puts the furnace further away from the gas cans that are on the floor that I have for my mower and tiller.

 

[PoorUB]

Most "old" funaces I took out were shot! That was the reason they were removed.

 

[Bert_]

I've got a used furnace in my garage. Pulled from a house because they wanted to add central air and I sold them a new furnace at the same time. Probably 40 years old but decent shape.

 

[The Cobbler]

A family member has a rental property, 1-1/2 yrs ago a new furnace & AC were installed while doing major reno's. I was tasked with taking the old furnace out of the basement , took it it to pcs to get it upstairs easier. the heat exchanger looked like new, no rust, no cracks . heavy as all get out. circa 1984 . 35 yrs old and no signs of being remotely close to failure . was locally made . the fan could have used some new bearings as it was noisy , but other than that it was flawless . no way the new install will be there in 35 yrs.

 

[etherhuffer]

old heat exchangers lasted, which is why they were less efficient. I asked at install if our new furnace would be serviceable in the future. The response was that the heat exchanger would likely fail faster than the old one. If circuit boards involved, those become unobtanium. It was a fortune to get an updraft fan for in-law's furnace

 

[BD1]

Some insurance companies will not insure or payout if the heater / furnace is not approved for garage use.