Converting Oil Furnace to Wood

Discussion in 'Homesteading Questions' started by ChiliPalmer, Jun 9, 2006.

  1. ChiliPalmer

    ChiliPalmer Well-Known Member

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    Got a couple of questions for anyone who knows a thing or two about furnaces. Say you had a basement forced air furnace which currently burns heating oil. You have a fair-sized woodlot on the property and want to convert the furnace to burn wood instead.

    1. Is that possible, or would you have to remove the entire furnace system and install a new one intended to burn wood?

    2. What are the costs of such a thing (removal and new installation or converting)? I'm not asking firm exact figures, any general ballpark would be great. Is it a simple thorough cleaning and new grate, or a moderately bigger job which costs moderately more? $800? $1800? $4800?

    Thanks!
     
  2. Gideon

    Gideon Well-Known Member

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    An oil fired furnace has a small firebox that the actual heat is generated in. I would take out the entire furnace or leave it for backup and duct in from the wood burner. Is your basement ground level or sub grade? Either way you could have the wood burner outside for ease of feeding. Lots are going to remote wood burning units that is piped in via closed circuit lines to your existing duct system. We have gone to wood heat nearly entirely but using a stationary heater(Ashley)and ducting overhead for distribution. The "gaspack" system is just sitting there-just in case. We have gas logs and gas heaters for backup plus gas range. No problem heating up the casa.
     

  3. ChiliPalmer

    ChiliPalmer Well-Known Member

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    Ah! I understood all that! Wonderful, and here I thought all the explanations I was sure to get would go right over my head. So, with a freestanding wood stove and tapping into the ductwork, you're just paying for the stove, brick and piping, yeah? How would the forced air be kicked on? (Below-ground basement, btw.)

    I've looked at those outside wood furnaces and they don't appeal, personally; it's a wasteful burn with lots of smoke and wood for less heat per cord. The upside seems to be that mortgage companies will accept it as it's outside. I would install one if the bank insisted, but otherwise I'd like to stick with an indoor heating system.
     
  4. myheaven

    myheaven Well-Known Member Supporter

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    I have just a plain old wood stove and my friend tought me a great trick. Turn on my furnace fan and it will cycle the hot air threw out the house. ANd realy it does. I tried it this march and my basment went from 34 to 54 deg f. We took and added a cold air retun tube to the celing (dryer vent) to pull the hot air from the top better. You can easly add on a wood stove to an exsiting furnace they run about 1000.00 in my neck of the woods. It depends on your sqft. The furnace (wood) runs the heat threwyour exsting duct work with either your old furnace fan or a new one on the wood stove. Ill see if I can get you a link.
     
  5. myheaven

    myheaven Well-Known Member Supporter

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  6. ChiliPalmer

    ChiliPalmer Well-Known Member

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    That thing is AWESOME. That's exactly what I needed to see, now all I need to do is estimate the installation and extras and I've got a figure to work with. +1 Myheaven.
     
  7. myheaven

    myheaven Well-Known Member Supporter

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    Call your local fire marshal and see the laws also your insurance person( if you have a loan on your house) Our only rule was ours had to be installed by a professonal and inspected by the fire cheif (fire cheif installed it). Wood heat ROCKS!!!!!!!
    MAke sure the wood is dry 2 years is best the btus are out of this world with 2nd year wood.
     
  8. Peacock

    Peacock writing some wrongs Supporter

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    Hm...I wonder if it would be possible to use something like this for a boiler/baseboard heat system? We also have an oil furnace, and it's pretty old, may need replacing in the not-so-distant future anyway.
     
  9. myheaven

    myheaven Well-Known Member Supporter

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  10. Peacock

    Peacock writing some wrongs Supporter

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    Well isn't that just the coolest thing! +2 myheaven! :)
     
  11. myheaven

    myheaven Well-Known Member Supporter

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    YEah i know im good!!!!! lol just kidding.
     
  12. myheaven

    myheaven Well-Known Member Supporter

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    Only thing that could make these the bomb is to have the fans cerulators(sp) and thermostats run on solar. then no worries when power goes out.
     
  13. fordson major

    fordson major construction and Garden b Supporter

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    two very important points are the distance the duct work is from the ceiling and the chiminey. wood heat, either a stove or furnace ,operates at a much higher temp then oil or gas. this means the distance to the joists is much greater than other means of heating. also the chimmney must be able to take a higher temp and may need to be larger/higher than it is presently. costs can run from 1 to 12,000. depending on how handy you are and how much of the old system you can safely use .after decades of heating with wood we are switching too an outdoor wood boiler, it can eat much crappier wood than an indoor stove and much longer lengths. much easier sleeping at night too, no worries of a chimmney fire and lots of heat stored in the water. and no more mess in the house, both dirt,dust and smoke!
     
  14. rambler

    rambler Well-Known Member Supporter

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    An add-on wood air firnace will run you $2000-3000 in materials. Or of course much more if you want.

    In addition these days you need a seperate chimney from the oil burner. Used to be oil & wood could share, there is little real concern but regulators need to regulate. (Gas furnaces do need a seperate chimney!)

    An add-on wood boiler (water radiators, baseboards, or in-floor pex heating) will run you about $3000-4000 in materials. Or, much more if you want. Many of the wood boilers can be plumbed to provide very limited heat during a power outage, the water will curculate by gravity. You can't build a hot fire, but keep things from freezing....

    There are ways to set up the controls to kick on the fan (or curculators for water sytems) to work with either furnace, and to allow the oil burner to kick on when the wood furnace runs low on heat.

    There are a few combination furnaces made that combine wood & oil, or wood & gas in one unit. These are expensive, but if you need to replace your old oil burner anyhow, might be worth looking at.

    I have a lot of links around, especially to wood boilers, from my research a couple years ago, if you want.

    --->Paul
     
  15. Ross

    Ross Moderator Staff Member Supporter

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    Some oil fired chimneys and furnaces can be co-vented with wood and work legally together. Converting the oil is out, it was never built to handle the heat from wood and would have no capacity anyhow. Ducting a woodstove into existing duct work is illegal here and likely everywhere. It also directly distributes any CO into your living space that leaks out of the wood stove. Adding a wood furnace to an oil fired central heating system is as FM describes, doable but with added clearances. Its your best indsie wood heating option even with a seperate chimney but it is going to be pricey. Do check your local regs and insurance, nothing is more expensive than re-doing the job!
     
  16. free-2-b-me

    free-2-b-me Well-Known Member

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    The former house we owned for some 20 years had a hot air furnace in the basement . For the last 15 or so years we lived there we heated the 2 story with an add on wood furnace . Put the add on right next to the furnace - ran duct from add on into furnace hot air plenum - ran the stove exhaust right into the existing chimney .
    I see the add ons all the time at Tractor Supply for under $1000 .
    The add on does have a blower and when you attach the duct to the hot air plenum the furnace blower also came on - we did that when it was really cold to boost the warm air - otherwise we just kept the furnace shut off.
    Wish we could do that here - we live in a mobile home now.
     
  17. moonwolf

    moonwolf Well-Known Member

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    My heating system is an outside wood burning boiler and a back up oil burning furnace that kicks on if I don't burn wood (two thermostats).
    There is a heat exchanger in the plenum above the oil furnace. Water that is heated from the outside wood burner is fed to the heat exchanger unit and when the blower fan comes on, the heat is distributed through the ductwork. If the water is not hot because wood isn't buring, the preset oil furnace thermostat kicks in and oil will burn to force heat through out the ductwork.
    Best system I've ever had for living in the country.
    You need to have an oil furnace which is the cost, when you add the outside wood burning furnace, that cost about $4000 if you trench and do the underground pipe work yourself. Payback on that at current oil fuel prices is about 3 years if one burns wood from their own woodlot. If you have to buy wood as here about $80/cord, than payback is about 5 years.
     
  18. free-2-b-me

    free-2-b-me Well-Known Member

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    That's what we want to get for here moonwolf but , my husband tends to think that it might not work with a mobilehome furnace . Whatcha think ?
     
  19. moonwolf

    moonwolf Well-Known Member

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    I don't see why not. If your oil funace has a plenum, the hot water to air heat exchange unit can be installed there. The size of that unit on my furnace is about 2ft. x 2 ft. x 6" deep. one end connects to input of hot water from the furnace and the other to flow out 'cold' back to the furnace via a mini pump.
    the furnace flower works to push the warmed air from when you use wood through the exchanger, and it puses warmed air if you burn oil.
    Even if you didn't have duct work and all that, you could have a separate squirrel type blower rigged up below that wood heat exchager to put warm air into a space. I've seen that done where a guy had the outside boiler but no indoor funrace system. He just used the heat exchager as the heat source and blew a fan (box fan) through that. It heated quite a large space bigger than a mobile home. I'd go with fitting into your plenum if possible for best use, and if you have the duct makes it backup to the oil furnace or vice versa. You can also heat your water via a heat exchanger unit to your hot water tank if you have the outside wood boiler. For about $100. You'll have all the hot water you need and want during wood burning season at no electrical cost except for the tiny pump.
     
  20. free-2-b-me

    free-2-b-me Well-Known Member

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    Thanks for the reply moonwolf . I guess I will call a couple of the places around here that sell them . I have spoken to a few people that have them and they love them. If we do decide to get it I would like it set up to heat the garge also .