retask old furnace chimney with woodstove

[mudbone]

Hello everyone. I know this topic has been batted around but my particular situation hasn't come up... or I haven't used the correct search terms. We're looking at a house that has a fubar/useless oil furnace. We aren't going to replace the furnace(we're going to go with a ductless split system... purely electrical). I'd like to use the old furnace chimney to vent a woodstove. We occasionally lose power in our area when it snows and I don't want to be beholden 100% to electrical heat. And using a kerosene heater is a pain in the backside. All the threads I've read here assume that people are trying to use the chimney for the oil furnace and woodstove at the same time. So that's not the case. The chimney would be dedicated solely to the woodstove. My intuition tells me that it's probably not a good idea to retask the chimney unless a liner/pipe is used. I'd appreciate your thoughts on the matter. Thank you.

 

[peakbagger]

If there is conventional tile liner inside the chimney and its in good shape (meaning inspected by a professional), of adequate size to match the woodstove, there is no need for a new woodstove specific liner. If the chimney is unlined I would be surprised it was used for oil.

 

[mudbone]

Mr. Peakbagger, (and anyone else reading who cares to chime in)
1st of all I wanted to say thank you for the reply. That was very helpful. I also noticed that you have "mini split heat pump" as part of your tagline and I was hoping you might answer a couple questions about ductless split systems. The Mrs and I found a nice fixerupper of about 900 sq ft(3 rooms, bathroom and the kitchen). The inside looks like a bad hangover but nothing some drywall mud, new linoleum and some paint wouldn't cure. I'm regarding it as a single bedroom apartment that isn't attached to anything. I was thinking about a Mr. Cool 2 Zone of about 27K-30K BTU's with the aforementioned woodstove for heat when it gets REALLY cold or we lose power. The house is older (1947) so I'm presuming it is not well insulated(we haven't done the inspection yet). That's why I'm interested in the 30K BTU range. I'd like an edge. I hate being cold. I'd appreciate your thoughts on MrCool or Alpine as a brand (I know Fujitsu rules but they're at the high end pricewise) and the choice of 27K-30K BTUs of capacity. Thank you.

 

[peakbagger]

You may want to wait a bit for others to comment. I gave you my opinion but others may have equally valid comments. I just happened to read it first.

I am a fan of Mitsubishi brand which is also pricey. I did my own install and therefore wanted to go with a unit with good long term reputation. If you go in the Green Room forum, there are a couple of threads on the Mr Cool and other lower cost (and usually lower efficiency units). If you have not contacted your utility yet I recommend you do they may have free or reduced energy audits and efficiency upgrades. Does not hurt to make the call. Money not spent on heating and cooling by air sealing and insulation is the best return on investment. With 900 square feet, the proposed mini split looks really oversized unless the place is real leaky building. Minisplits are perfect fit for most of the middle atlantic. I am way up in northern NH and my 12000 btu unit keeps about twice the square footage down to about 30 degrees and covers my AC needs for about 1000 square feet. Where a minisplit is not so good is when the temps drop down below about 20 F. Yes they still put out heat but less of it and are less efficient. Air based heating usually is bit less effective than hot water radiant so most folks tend to keep the thermostats higher.

Given your square footage, my guess is you will end up with small woodstove. Woodstoves are mostly radiant heat and if you can see the stove in small house you are getting heat from it. Its a PITA to get the heat to move around closed off rooms. That means the area around the stove is hot while the bedrooms may be cold. The other thing to consider is in order to heat with a modern stove, dry wood is not optional, the wood has to be dry for typically 2 years and has to be stored ready to go. In an emergency situation its too late to go looking for dry wood. There are biobricks (basically compressed sawdust) that dont take up much room and are good in pinch. My guess might be the latest version of Jotul 602 has a small footprint and would throw off plenty of heat.

 

[xman23]

I agree, with peakbagger, an old lined oil burner chimney could work for a wood stove. Of course the condition needs to be evaluated. I know two people that have new multiple zone, inverter speed drive, heat pumps. They work for heat and air conditioning. With motor speed compressor control they have become economical to operate. My daughter and a friend say they are much cheaper than oil or electric. Although there efficiency does fall off the colder it gets. I'm sure someone here will have the numbers on that. I've been considering doing this for sometime. They have started making cassette size units that can fit into ceiling and walls. Much nicer look than the units hanging on the wall.

 

[bholler]

Yes the chimney certainly could be useable. You need to have it inspected