# Outdoor Wood Furnaces



## BisonMan

I am building a house on my farm property and since there is no Natural Gas I am going with a wood boiler and propane as a backup.

I was wondering if any of you guys had them, if there were models that you would recommend, things to avoid / consider


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## Wethay

I looked at them many years ago. The plan was to use wood almost exclusively, but to have a back up fuel source for a prolonged absence from the house, illness, etc. I was going to go with diesel as the secondary fuel source because it would be around and would be kept from getting old by running it through the farm equipment. I was looking seriously at one that had a stainless steel firebox. I learned a guy at work was looking at them and we compared notes. He was going with a steel firebox. His thinking was he didn't know how to weld stainless but if he ever had to repair/ replace his firebox he could do it if it was steel. Made me rethink some.


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## Aaroncboo

If I'm not mistaken I think somebody I'm here either sells them or has one. Maybe they'll chime in. They're definitely a neat concept


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## swmnhay

Aaroncboo said:


> If I'm not mistaken I think somebody I'm here either sells them or has one. Maybe they'll chime in. They're definitely a neat concept


MLappin,

Marty does


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## PaulN

When Marty comes along, he will be able to answer your questions better then anyone else here. He sells and installs them.

In the mean time, here's my experience. I've had one since 1993. It sits 140' from the house. We have LP for backup, but rarely use it. The house is 110 years old, so not the most energy efficient. I go through ~10 cord a year, plus or minus, depending on the year. Most people with more modern homes will use 3 - 4 cord a year. In case you're wondering, yes, the fire will last all night. As long as you are in good health and don't mind cutting firewood, I say go for it.


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## slowzuki

Lots of rotted out ones for sale, I would do your research on the brand before buying. They are not the easiest things to patch.

We considered one when building but didn't due to the cost for a quality one at the time. I think in retrospect the time savings of burning big chunks rather than finely split wood inside would have been a good move even at twice the cords.

If you live near other folks make sure it's not oversized as they smoke like a freight train when the damper slams closed. That's the biggest complaint around here about them.


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## Wethay

I know that several years ago I was still on the mailing list and got "buy now before price goes up because of regulations... Like wood stoves have fallen under the realm of pollution control so have wood furnaces. At least one offered a quick start option where it would burn diesel for a short amount of time to get the fire going again when the draft opened, but I have thought that it would be nice if the draft was controlled a bit instead of just opened or closed. I had also thought that a lumber kiln would be nice for the spring and fall when some heat in the house, mostly during the night, would be nice but it wouldn't be much work for the furnace. The furnace would provide heat for the kiln until it was needed in the house.


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## RockyHill

As Cy (swmnhay) said MLappin will be an excellent resource.

We had a Central Boiler at the farm we sold about 11 years ago. We considered moving it but mistakenly thought it wasn't worth the effort. We wanted to go a less expensive route so we installed a Ridgewood where we live now. It used repurposed tanks for the firebox. Works well for us. We also use a heat exchanger for our domestic hot water. We built a domestic water heat exchanger with the Central Boiler and bought the plate style that we're using now. Really haven't seen any difference between the two styles. The huge mistake we made with the one we have now is the insulated pipe. With the Central Boiler the line to the house did not melt snow-ever. The pipe that came with this one loses a lot of heat. Where it comes under the concrete walk, even rain water evaporates quickly.

We use baseboard heaters and also have a heat exchanger with a fan behind it for the side of the house that baseboard heaters wouldn't work.

As mentioned, the smoke can be a concern to neighbors.

Shelia


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## BisonMan

Wethay said:


> I know that several years ago I was still on the mailing list and got "buy now before price goes up because of regulations... Like wood stoves have fallen under the realm of pollution control so have wood furnaces. At least one offered a quick start option where it would burn diesel for a short amount of time to get the fire going again when the draft opened, but I have thought that it would be nice if the draft was controlled a bit instead of just opened or closed. I had also thought that a lumber kiln would be nice for the spring and fall when some heat in the house, mostly during the night, would be nice but it wouldn't be much work for the furnace. The furnace would provide heat for the kiln until it was needed in the house.


The good news is that my farm is fairly distanced from the neighbours. The neighbours are also more salt of the earth types rather than the country estate types so they are pretty down to earth. So I don't see myself getting any complaints. The neighbouring farm has one so I will check in with him.

The idea of wood falling under pollution control is a scary thought, sign of the times I suppose. There is no natural gas line going to the house. Part of the appeal was that here up in Canada there is an ECO Tax which is in place and being brought in more and more every year. The thought of heating on propane as a Long Term Plan seemed risky as I've heard prices could fly, especially when you put on the eco tax. I have 40 acres of woods on the property, so my plan was to just chop up some fallen trees each year and toss them in. The self sufficiency idea really had me excited to be honest.

Well, there is no real way around it as I see. I'll just have to hope that the government over reach doesn't find me. I'll check into current regulations and see if it's allowed. The idea that it burning my own lumber could somehow be taxed or counted as pollution is pretty ridiculous.

Thanks for all the replies, I appreciate all the feedback. I'll be hunting around to buy one in the next couple months and will definitely keep everyone in the loop as I go through the process, plus pics. Really appreciate the help, there aren't a ton of people who have these but some farmers do.


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## Uphayman

I heat a 1750 sq. ft. house, lots of windows, built in 1976. Currently using a Crown Royal 7300 MP. Has a stainless steel fire box. Also have a backup propane furnace. Maybe used twice a year before start up. Neighbors aren't an issue. Wood supply on the property is endless. Self sufficiency is great. Don't care what propane price is. For me it's part of the fall gathering.......finish the garden, knock out the broilers, fill the freezers, fill the woodshed.


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## KurtS1

If you hate to cut wood, then don't buy a boiler.

I have had a Central Boiler for 15 plus years. It is a 6048. I am very happy with it. My house (ranch) was built in 1978 and has decent insulation and newer windows, we keep the house between 72 and 74 degrees (no real hot or cold spots like with a wood stove in the house). I have a fuel oil furnace and do not use it. (It should probably be replaced.) I also heat my 20 x 40 x high ceiling (reasonably insulated) shop. I am not in there all of the time, but maintain it at 45-ish degrees, when I am not in there.

I don't honestly know how much wood I use, but I do burn a lot of wood. I live in SW MI and the temps vary, but it does get cold. I start the stove in Sep or Oct, when it starts to get cool at night. If the inside of the house gets to 65-F, I start a fire. In this kind of weather the furnace fan doesn't even run. The house is warmed just by the hot water in the pex tube that makes a loop through my basement. The basement is also warm, nice and warm. When it is bitter cold out, zero-ish, I need to fill the stove twice a day. it is a good idea to check it at least twice a day anyway. I usually quit burning in May (we sometime have to open the window on the warm sunny days, but don't have a cold house after the sun goes down).

I usually burn only down and dead stuff, out of the woods, I don't have to drop many trees, because of that. The stoves will pretty much burn anything. Green wood, seasoned wood, in between wood, half rotted wood, it ALL burns. I don't like to split wood and the 6048 has a big enough door, that if you can pick it up, it will fit through the door. I would strongly encourage you or anyone to get the 6048 size over the smaller stoves. My mom has the 5030 size and I spend more time cutting wood for her stove because I have to split it (I have to get it to old lady handling size anyway). That stove is still better than an indoor wood stove and will still take a good sized log, but I prefer not to split my wood.

There are lots of choices in stoves, many more now, than when I bought mine. I bought a Central Boiler, because that is what my dad had and several friends as well. My brother and I and several buddies all bought at the same time and we got a better deal. We had a decent dealer at the time (we have a better one now) and because we hall had the same brand of stove, we had commonality of parts. Circulation pumps rarely quit during the day, when the dealer is open. Obviously, you want to find a Good dealer and a Good, well built stove. It is going to be a sizable investment and quality is important and 15 years goes pretty fast. I have had good luck with CB, but others have not. My buddy bought a new one that leaked from the factory. It was covered under warranty, but he had to pay to have it shipped from MI to MN and back.

Would I buy another? ABSOLUTELY! Would it be a Central Boiler? Maybe, but I would certainly shop around!

If you hate to cut wood, then don't buy a boiler. If you don't have a good wood source, then you probably don't want a boiler. If you want to pack up and go to FL, for a month in the winter, then don't buy a boiler.


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## mlappin

The new high efficiency boilers use considerably less than the older models or even the newer multi pass units. However if you're a cut as you need it guy then you'll want to stick with a multi pass like the HeatMasterSS C or MFe models or the MP series from Crown Royal. High efficiency models like the G Series from HeatMasterSS or the Pristine Series from Crown Royal take a little better seasoned wood but they'll burn about 20-30% less than the multipass models and 50% less or more than the older conventional smoke dragons. I run a HeatMasterSS myself and sell and install as well, only reason I mention Crown Royal as they also use 409 stainless for anything that touches fire or water and just like HM they don't disappear when warranty issues arise. Unlike some other brands both CR and HM will hire a welder to fix it on site, no foolishness of having to pay to have it shipped back to the factory for repairs then back to your place.

I seen it mentioned about modulating the air flow, only HeatMaster has true modulating dampers on the new G Series, the newest series of G's of which I'm running one now actually has two dampers, one controlled mainly by temp and the second by a industrial grade o2 sensor, works just slicker than snot on a doorknob.

My Youtube channel, mainly about the older G Series but adding videos on the newest one weekly.

https://www.youtube.com/c/AlternativeHeatingSolutions


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## RockyHill

Circulation pumps rarely quit during the day, when the dealer is open.

Would I buy another? ABSOLUTELY! Would it be a Central Boiler? Maybe, but I would certainly shop around!

If you hate to cut wood, then don't buy a boiler. If you don't have a good wood source, then you probably don't want a boiler. If you want to pack up and go to FL, for a month in the winter, then don't buy a boiler.

Definitely have an extra circulation pump on hand. That was one thing the dealer told us when we bought the Central Boiler. Fortunately the pumps we've used have given good service but they are a wear item and heat doesn't get to the house without it.

Unless you have a system that can keep the water heated with another heat source and circulating, it will need to be fired with wood the entire season. We're working toward building a new house and we will not be using a boiler in it. We're getting older and if something happened that we couldn't be at home (or able) to fire the stove we'd have a big problem. Yes, family/friends could help but for the long term the water lines would have to be redone some way.

Shelia


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## Shetland Sheepdog

RockyHill said:


> Circulation pumps rarely quit during the day, when the dealer is open.
> 
> Would I buy another? ABSOLUTELY! Would it be a Central Boiler? Maybe, but I would certainly shop around!
> 
> If you hate to cut wood, then don't buy a boiler. If you don't have a good wood source, then you probably don't want a boiler. If you want to pack up and go to FL, for a month in the winter, then don't buy a boiler.
> 
> Definitely have an extra circulation pump on hand. That was one thing the dealer told us when we bought the Central Boiler. Fortunately the pumps we've used have given good service but they are a wear item and heat doesn't get to the house without it.
> 
> Unless you have a system that can keep the water heated with another heat source and circulating, it will need to be fired with wood the entire season. We're working toward building a new house and we will not be using a boiler in it. We're getting older and if something happened that we couldn't be at home (or able) to fire the stove we'd have a big problem. Yes, family/friends could help but for the long term the water lines would have to be redone some way.
> 
> Shelia


We went through 15 years, in a big old farmhouse, with an OWB. We were burning from 15 to 20 cords of wood a year, including our domestic hot water. Then we built a new house, and went with Geo Thermal for our heating and AC. No more firewood prep, no more boiler tending regardless of weather, no worries about heat if we decide to go away. Only issue to be concerned about is power outage, so, we had a whole house auto generator installed!

HTH, YMMV, Dave


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## mlappin

RockyHill said:


> Circulation pumps rarely quit during the day, when the dealer is open.
> 
> Would I buy another? ABSOLUTELY! Would it be a Central Boiler? Maybe, but I would certainly shop around!
> 
> If you hate to cut wood, then don't buy a boiler. If you don't have a good wood source, then you probably don't want a boiler. If you want to pack up and go to FL, for a month in the winter, then don't buy a boiler.
> 
> Definitely have an extra circulation pump on hand. That was one thing the dealer told us when we bought the Central Boiler. Fortunately the pumps we've used have given good service but they are a wear item and heat doesn't get to the house without it.
> 
> Unless you have a system that can keep the water heated with another heat source and circulating, it will need to be fired with wood the entire season. We're working toward building a new house and we will not be using a boiler in it. We're getting older and if something happened that we couldn't be at home (or able) to fire the stove we'd have a big problem. Yes, family/friends could help but for the long term the water lines would have to be redone some way.
> 
> Shelia


Numerous ways around all those issues.

I have a Grundfos 26-99 I bought in 2001 still in service, mount the pumps AT the boiler, they won't pull water, only push.

Numerous ways to keep em from freezing. I have 165 gallons of inhibited propylene glycol to add to a boiler down the road one of these days soon as we get his overheating issues fixed, NOT one of mine, some off breed pressurized coal burner.

Cleverest I seen and the company may not agree with it, but our boilers are 100% 409 stainless for anything that touched fire or water, the guy has like four plastic 55 gallon drums he takes in the basement and after its out and cool he drains the boiler into the drums, when they get back from Florida he pumps it back into the boiler. Doesn't bother a stainless boiler much being exposed to oxygen after having water in it but it will eat a mild steel unit in no time.


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## mlappin

Wethay said:


> I looked at them many years ago. The plan was to use wood almost exclusively, but to have a back up fuel source for a prolonged absence from the house, illness, etc. I was going to go with diesel as the secondary fuel source because it would be around and would be kept from getting old by running it through the farm equipment. I was looking seriously at one that had a stainless steel firebox. I learned a guy at work was looking at them and we compared notes. He was going with a steel firebox. His thinking was he didn't know how to weld stainless but if he ever had to repair/ replace his firebox he could do it if it was steel. Made me rethink some.


Oh yah, you'll need stainless wire and some sort of tri-gas as its near impossible to get a helium mix anymore but 309l or sl wire works really well on 409 stainless, its not near as tricky to weld as other stainless grades and pretty much works and machines like mild steel.


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## U Lazy V Ranch

I have a Central to heat my shop (I'm thinking it was put in about 1997, so definitely not a new one). I think a lot depends on your wood. We have lots of Lodgepole here. It's not a hardwood, and I really think that's what's best for these boilers. I've gone out at night and there's a 4' high flame from the top of my pipe....not what I call terribly efficient. This fall I've moved it inside, and have a huge heat exchanger I built that will go on top, to try to catch some of that excess heat. I love animals, but I'm not feeling the need to try to keep everything warm outside!  
I've talked to a bunch of people that are really happy with theirs, and it sounds like they're much more efficient now a days, so it's probably not a decent example.
I will say one thing, the greatest thing in the world is warm floors!!! In the shop, if something comes in at night, it's warm and dry in the morning and that's sooooo nice!!!

I definitely would put another in, even with the extra wood I burn, it's a pretty cheap heat source!

John


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## mlappin

About wood consumption, I'm heating 2800sqft of 1853 farmhouse and 1850sqft of shop that used to be a cow barn, no vaapor barrier under the floor, zero perimeter insulation and insulated with Plyfoil which isn't that good but better than nothing. I got it for free, if I had known then what I know now I wouldn't have wasted my time installing it, neither structure holds snow on the roofs for long and I usually refer to the shop as the sieve. Also heat 120 foot of sidewalk when required. Usually burn 8 1/2-9 cords a winter, but supplement the wood with the waste oil boiler in the shop spring and fall when it just isn't worth keeping a wood fitre going.


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## Mad mark

built a small modular boiler I can mount on any wood stove so far it works very well radiant in floor heat got about a hundred bucks into it


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## Mad mark

It's kind of crude it's my first boiler I've ever built and it's going into my cabin up north once it's past its trial tests at home only about 500 square feet with PEX pipe runs in built into the insulated subfloor. runs on top the insulation obviously. Using an old hot water tank is a reservoir. Does anyone see an issue with this design layout?


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## Wethay

About 25 years ago I was looking some of them had diesel burn options. One had I believe four settings: wood only, a quick burn of diesel when the draft openned to help the fire get going again with less smoke, then a wood/ diesel option where it would open the draft and if it didn't heat up in an amount of time it would burn diesel for that heat cycle, and then a diesel only setting. My thought was to set it to the wood with diesel back up setting and keep wood in it at all times so I wasn't buying diesel, but if for some reason I was unable then the house would still be warm. I have no idea what is available now.


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## Gearclash

Couple things I’d mention. For best efficiency run the coolant counter flow to the flue gas; cold coolant in the top of the exchanger, hot out the bottom. The other thing is, I would really watch the flue temperature after the exchanger. I think it will be really easy to over cool the flue gas and cause creosote buildup problems. I have a shop made wood stove for my shop that has air cooled exchanger tubes in the top and that will pull the flue temp down a 100-200 degrees.


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## slowzuki

How are you going to clean the hx tubes? They will plug up. You will want to line that stove with fire brick to burn as hot and clean as possible to extend the time before they plug up.



Mad mark said:


> It's kind of crude it's my first boiler I've ever built and it's going into my cabin up north once it's past its trial tests at home only about 500 square feet with PEX pipe runs in built into the insulated subfloor. runs on top the insulation obviously. Using an old hot water tank is a reservoir. Does anyone see an issue with this design layout?


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## JayRob

I would definitely stay away from Earth brand wood boilers


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