heating with wood

[coldyny]

i am planning to build a hot water boiler that is wood fired to heat my home,having an HVAC back ground as well as controls i think i a good plan but would welcome any comments

[fabricator]

Will you have to buy wood?

[cardamon]

I have burned wood my whole life and when I build my next place, I will be doing a wood heating system with a large thermal mass.  This would be either a giant water reservoir built around the stove, or a large concrete slab with tubes in it.  The goal would be to be able to run the fire wide open and cranking the way wood likes to burn, and then have enough heat stored to last a week - sick of having a stove be so dependent on me and worrying every time I'm gone for more than half a day.

[divemaster1963]

There is companys her in the southeast that build wood fired boilers for home and water heating. look them up for some ideas if you plan on homebrewing. they have thermosatic vents to contorl the burn. they can run upwards of 96 hours on one load of wood in the fire box. they burn very effectently. A neighbor has one that heats 3 homes and the water for them. and heats a 15000 sq. ft shop to work on construction equipment. works great.

john

[hiker]

ive burned wood for years also--55gal drum stove -and twin 100 gal stove- top one being a heat exchanger big hole throu center fan in back..

once you get it fired up and burning good --turn the air intake down plus the damper

makes for a hot fire that lasts a long while..saves on wood big time--otherwise all the heat goes up the stack and your wood burns up way to fast!!! my dad was a homesteader up here years ago-learned from him...

ps: coals are hotter than a flame.......

[Kwazai]

When I worked in the sheetmetal fab business, the shop foreman built his own. basic construction was internally similar to a two barrel heater from plate steel, surrounded by a big well insulated water tank. The doors came off a standard plate steel wood heater(what used to be called a cast iron stove). He had modified the doors for an intake fan. The water temperature controlled the fan on the intake side, which 'stoked' the fire to keep the water temp up. The water was piped thru buried insulated lines to a series of 'fan and radiator' type heat exchangers in the house, though it would have worked equally well with radiant floor plumbing. He had to feed it about every other day in freezing temps, less in warmer weather. He used a propane water heater, rather than kicking the temp up for hot water. (log home in the boonies...)

fyi

mike

[WA3PYI]

Building your own wood boiler is certainly do-able.  Building an efficient wood boiler is whole different story.  Consider the Outdoor Wood Stoves that are quite common in many areas of the country.  These are wood boilers and because of this they have been exempt from EPA regulations that have applied to wood stoves for over 20 years now.  Outdoor Wood Stoves (boilers) are typically some of the most inefficeient wood burning devices ever made.  There are exceptions - consider the following which use wood gasification technology:

Tarm wood gasification boilers-made in Denmark and sold through Tarm USA in Lyme, NH:

http://www.woodboilers.com

The Wood Gun gasification boilers- made by Alternate Heating Systems in Southern Pennsylvania:

http://www.alternateheatingsystems.com/woodGasification.html

the GARN. A large boiler, usually installed in a garage or large outbuilding.

http://garn.com/Default.aspx/

The Wood Doctor Converter.  From an Outdoor Wood Boiler company. Scarce information.

http://wooddoctorfurnace.com/converter.html

The Econoburn boiler.

http://www.alternativefuelboilers.com

The Seton stove doesnt use wood gasification but is still a fairly efficient boiler:

The Seton stove - A boiler made by Fred Seton & Seton Mfg. in Montana:

http://www.montanastove.com/

For more input about burning wood efficiently check out the following site:

http://www.woodheat.org/

Myself, I have a Tarm wood gasification boiler with an 800 gallon water storage tank.  Heat an old 2000 square ft 2 story farmhouse (including domestic water) with about 6-7 cords of wood/ year in northern PA.

[hydrosun]

I was looking into the gasifier wood boilers and came across the info that some users were having to replace the refractory liners around the fire every few years. Seems the stress of the intense 2000 degree burns and cool off was cracking them. Have you experienced this? If that happened it would nullify the cost saving of burning less fuel. The wood boilers are so expensive to begin with.

I'm now working on adding water pipes to the outside of a normal efficient wood stove. That way the heat from the stove is radiated inside the home and some of the heat is stored in a water tank. I do that now with an older wood stove and will do that on a newer stove soon. I don't know the limit of how much water can be heated this way. But it doesn't modify how the stove works internally but just moves some of the heat with water instead of just with air convection.

chris

[chainsaw]

This is our first full winter useing an outside wood furnace and could not be happier. It is connected to a radiant floor system and also a heat exchanger in the duct work. Heat pump thermostat is used for fan control when more heat is needed (cold windy below 20f) than can be delievered by the radiant floor system. The water temp is thermostat controlled by turning a combustion blower on or off. With seasoned wood there is NO smoke when the blower is running and very little during the resting stage. Our domestic hot water is a nice by-product. I fill the stove in the evening and have no trouble maintaining water temp till the next morning.

There's many good wood furnaces available and would be very easy to copy some of their best features in a home built unit.

[WA3PYI]

Hydrosun,

We have been using our Tarm since Jan of 2004 and the refractory parts are still the originals.  The main pieces on the bottom of the firebox that have the air injection passages are starting to get a bit worn and I am thinking about getting a new set just to have on hand.  I've read on other forums that a new set of refractory pieces is somewhere around $300-400 from Tarm.  And yes, a wood gasifying boiler is an expensive investment but every time the price of fuel oil jumped over the past 6 years I just smile - we still have fuel oil in our tank that was purchased over 6 years ago at around 1.34/gal.

Chainsaw - I'm not saying an outdoor wood furnace won't produce heat.  Many have a much greater BTU output than a wood gasifier.  They just aren't as efficient.  My brother has one to heat his 10 year old well-insulated home and he uses about twice as much wood as I use to heat our 100+ year old moderatly insulated farmhouse.

[JSNH]

Heating with wood In New Hampshire.

I have been heating with wood for 30 year. The first 10 with an air tight wood stove in the house. I burned good dry hard wood. The house was too hot or too cold. You had to bring the wood into the house and the house was drafty due to pulling in combustion air. You had to clean the chimney.

I then got a wood gasification furnace it also stored the heat in a 2,000 gal water tank. I burned good dry hard wood. I heated that way for 17 years. It would be similar to the tarm with a storage tank. It worked well every room was exactly the temp you wanted. Base boards for heat. I don't think I burned 300 gal of oil in those 17 years. It burned so hot no chimney cleaning was required except to pull a bit of dust out of the clean out every other year. You had to bring the wood into the house and the house was drafty due to pulling in combustion air plus when it was running the fan and circulator were loud. The stove's fire brick burned out and it needed a major rebuild. The fire brick shapes in it were custom and no longer available plus the tank developed a leak. I replaced it with an outdoor boiler.

I went with a standard Central Boiler 5036 outdoor boiler. It is great. I am into my 3rd winter. I did not want a gasification one. I am glad I did not get of those. In my opinion they are too complicated and problematic from the people I know that have the Central Boiler Eclassic 2300's. I may burn a bit more wood but I burn everything, pine, hemlock poplar and hardwood. I swear it runs better with pine. No chimney cleaning. No wood in the house. No drafts. No sound. I spend way less time filling, poking, cleaning and can spend more time with the family. The house it totally comfortable. We have more room in the house without the wood stove and without the furnace.