Wood furnace warped - worth/safe to repair?

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New Member
Feb 6, 2024
New Brunswick
Hi all, I was directed here after making a similar post elsewhere asking for opinions. Disclaimer; new to home owning, oil heating, and wood heat.

We purchased our home last month and it has a combo oil/wood furnace heat system. We had a small flue fire last week, which prompted me to schedule a service and cleaning of the wood furnace. We were assured that the chimney and furnace were serviced regularly, and took it at face value. We had been burning in it for over a month nonstop, fighting off some bitter cold days with ease.

During the service, the tech mentioned the inside being completely warped and the furnace being unsafe to use. He also noted heavy creosote buildup in the chimney and mused it likely wasn't cleaned in well over a year. We never lit another fire after the flue fire and turned to oil only, so we thanked him for the warning and began to price out a repair.

My question to this community is this; is it worth a repair, or should we scrap it? Our initial plan this spring was to remove the oil furnace and install cold climate heat pumps with wood auxiliary heat. However, the repair to both furnace and chimney (clay liner is cracked) is a little pricey, but we love the wood heat and we have over two full seasoned cord left to burn. Oil is prohibitively expensive ($2000+ CAD per tank) so it's an unfortunate situation to find ourselves in directly after purchasing the home.

Any and all thoughts are welcome. Thanks in advance!

Wood furnace warped - worth/safe to repair?

Wood furnace warped - worth/safe to repair?
Wood furnace warped - worth/safe to repair?
Wood furnace warped - worth/safe to repair?
Check your owners manual. Many of the firebox parts are usually wear items & can be replaced.
That looks to be quite an old combo wood boiler. The problem with dual fuel units is the efficiency on either fuel is usually quite poor. A modern oil only boiler would probably reduce your usage by 10% minimum possibly 20%.

I was working on similar vintage unit wood only boiler a few years ago to get it going again and even found a manual (I think I got it on this site). The front loading door was in rough shape and I ended up having to weld in new hinges. It is a pretty simple design and probably never was airtight. As long as the controls are working and set correctly, the safety relief valve is in place and plumbed into the firebox and it will hold pressure it is probably usable. It is a very simple internal design and easy to clean but not very efficient. I dont really know how it could be "warped" except for the front loading door which is not part of the pressure vessel. The hinges on the door in the picture were rusted to the point that I couuld not open the door fully and I had to cut them off and welded in new hinges, then drilled and shimmed the new hinges so that the door sits flat but definitely not airtight.

The big issue is that without thermal storage its real PITA to run, it probably good in very cold weather with someone stoking it to match the load but once its capacity exceeds the heating demand it really had no good way of reducing load except cutting off the air with the air flap. Put in too much wood and sometimes the air flap will not stop it quick enough and it will overheat putting heat into the dump zone (if the dump valve is working and connected). In some cases, even that will not work and the safety relief valve will open and dump water into the firebox (making a big cloud of gray ash and water vapor come out of the air flap coating everything with ash within five or six feet).

The second that air flap shuts, its creosote maker so I am not surprised it had a lot of creosote in it. Since its pretty much and all or nothing boiler, it can burn poorly seasoned wood to some extent and that makes the creosote problem even worse. It is not that hard to clean the boiler but until someone gets used to it the chimney may need cleaning a couple of times a winter.

In the case of the boiler I was working on which had not been run for awhile, after I talked with the owner and got her memories of all the issues they had operating it mostly related to lack of storage, they elected not to run it and its still sitting there. BTW, the manual indicated that there is asbestos sheet under the bottom of the refractory. Not an issue unless someone is chipping out the refractory but a potential disposal issue.

Wood furnace warped - worth/safe to repair?
I think this is a furnace not a boiler...
It looks bad because of not only the warp ,but possibly openings in the burn chamber.
No to repair it.
If you like the heat of wood then get a stand alone efficient wood furnace and get you heat pump as well.
I don't think there is a new wood oil combo furnace made any more
I agree it may be, but its still a very primitive beast made by the same company. If it is wood furnace it needs to be smoke tested to ensure that the heat exchanger is not cracked.
That's an old inefficient (dirty burning) wood furnace, and has been run hard, hence the warped firebox...and old overheated steel does not take repairs well...I'd call that machine scrap.