Desperate Times Call for Desperate Measures... a.k.a. I Need Advice on my Ancient Wood Furnace

[cassieUP]

There is an old wood furnace in our house that is hooked up to our propane forced-air furnace in the basement. We don't know a very much about the wood furnace. The woman we bought the house from said her parents used to only heat the house with wood and electric baseboard heat.They had the gas furnace installed a few years ago, and the wood furnace is hooked up to the gas furnace.

We had no plans to use the wood furnace until last Thursday when our propane supplier called us and told us propane was up to $5.99/gallon (we paid $1.99/gallon back in November so we were pretty shocked). After spending almost $700 for 110 gallons of propane, we decided that it was time to try out the wood furnace because there is no way we can afford to heat our house with propane at this time.

We are not at all prepared to heat with wood, but we really don't have a choice now. I'm pretty sure the wood furnace is homemade. It seems to be build pretty well. The sides stay cool enough to touch while a fire is going. What we are confused about is how it works. There is a big steel box attached to the side of it, and we assume it used to be the blower for the furnace because it is attached to duct work that is not attached to the gas furnace. Except now, it sucks air out of the unused floor vents and into the wood furnace when it turns on so I guess it's now a cold air return. The ducting that comes out of the top of the wood furnace is attached to the plenum of the gas furnace, so when the cold air return comes on, the gas furnaces blower motor turns on and sends the heat up through the new ducting and floor vents. There is a damper on the front of the wood furnace, and it looks like it should be automatic, but the motor seems to be seized up so we have been opening it and closing it ourselves.

I have been using the top-down method to start fires, and I am having much better luck with the furnace than my husband. I'm using the north-south orientation when I load the wood. I am not using as much wood as I would like because our wood supply is very limited until we get a delivery (hopefully) in the next couple of days, and the temps could get down to -20 in the next two days. I can usually get the house up to about 61 degrees. I let the fire burn down and start it back up in 4-5 hours when the temperature gets down to around 57.

I guess my main question is about what I think is the cold-air return/intake. Is it making this process more or less efficient? Part of me feels that it's a waste of electricity (which is also insanely expensive up here) and make the wood burn too fast, but the other part of me feels that it must make the wood burn hotter and therefore is better for creating more heat. I'm assuming part of the reason the wood is burning so fast is because it's really old, too dry, and some of it is pine. Also, any tips to make this process work better? Buying a new wood furnace is not an option at this time. I just feel like I am putting in a lot of work and I'm still pretty cold.

Sorry about the long post, but I'm at a loss right now, and I'm kind of panicking because there doesn't seem to be any relief coming in the weather or propane prices. We have our gas furnace set to kick on if the house gets to 50 degrees, and it hasn't kicked on since we started using wood. We plan to use wood again next year and will actually be prepared for it. I will really appreciate any advice!

Cassie

 

[Boil&Toil]

Pictures would be a great help here.

Do you know, or can you tell, if the furnaces each have their own flue or are sharing a flue? Have you had the flue inspected? It can cost you a great deal more than absurdly expensive propane if your wood furnace (about which you know little) sets your house on fire, so some caution is called for, even (or especially) in desperate times.

 

[Kemer]

Please be careful I have two friends who lost there houses due to wood burners

 

[cassieUP]

I don't believe the furnaces share a flue. The gas furnace is high efficiency, so it vents out a pvc pipe on the side of the house. The wood furnace and sauna stove share the same flue, and we use the sauna stove all the time without problems. I would much rather be using the propane furnace and just start using wood next winter after we have had time to properly prepare, but it's not really an option right now.

 

[Buzz Saw]

I have a similar set up with a Hot Blast furnace.Looks like the wood burner has it's own cold air return then send the hot air into the propane plenum for distribution. Does the propane fan blower have to run to move the air? Assuming there is a blower in that box next to the wood burner. If my hot blast had larger fan I wouldn't have to run the propane fan.

 

[PastTense]

Do you still have the electric baseboard heaters in the house? If they and the house wiring are still in good condition that would probably be about half as expensive as your $5.99 propane. How much are you paying per kilowatt hour of electricity? If not you might buy a couple space heaters to help out (assuming you have good wiring). Note the safety recommendations about electric space heaters.

You might ask the person who delivers the wood for their opinion. Obviously if the delivery person is a teenager they probably wouldn't know much but if an older adult who has dealt with wood all his life definitely.

 

[STIHLY DAN]

Get a carbon monoxide detector now. Starting an old unit with no info or history of it in a last minute frenzy could be bad. very bad. If the wood unit has a fan, the gas fan should not run.

 

[jdogg]

A. Clean furnace and check for holes or cracks in firebox.
B. If A is ok ck. stovepipe to chimney replace if needed.
C. Sweep chimney (from bottom if roof is snow covered) At bare min. pull stovepipe out of chimney and ck. chimney with a handheld mirror from the bottom on a sunny day. Should be clean with little to any cresote build-up, no nests or buildup of any type.
D. Start a small fire and see if OK, smoke going up and out, furnace blower should come on etc. A furnace without a blower yeilds only radiant heat. (50% or less IMO)

 

[jdogg]

I'd come look at it for you but my guess is your in the UP and im not going up there (Sault Ste Marie) to see the grandkids before March.
Should be a fair amount of local woodburners get someone who knows what their doing to look at this furnace ASAP!

 

[stee6043]

It's been a cold one in Michigan, that's for sure!

If I were in your position I'd pay a pro to check the chimney, make sure I have CO detectors on every floor, double check smoke detectors and fire extinguishers and then start small. Small fire to get things moving and see how it all works...