Outdoor wood boilers

[rogdan]

Outdoor wood boilers

I am considering one for our home heating (new construction) I am interested in comments from current users especially as to reliability and maintenance. Has anyone use one for 5 or more years without major problem? Thanks

 

[dmp437]

Re: Outdoor wood boilers

Do a search, both on TBN and Google.
To get you started take a look at THIS LINK
In short, outdoor boilers are about 20% efficient and although there are some good ones (meaning they last longer than the warranty) the majority are suspect.

 

[dbelisle]

Re: Outdoor wood boilers

I have to agree with these comments . I installed a outdoor wood boiler for a farmer 12 years ago and he is on his second boiler and getting ready for his third.

He has been happy with the system , It heats his house, his domestic hot water in the house , milk parlor and the domestic hot water for the parlor. He is milking about 200 head so he goes through a ton of hot water.

Even though the boilers haven't been lasting more than 5 or 6 years, It has paid for it self and the replacement boilers many times over.

He is cutting the wood from around his fields to keep them from growing in , so the energy is free. And He will cut after the chopping season is done so it keeps his help busy.

They work good if you need a lot of energy. but you will go through a lot of wood. ( You can throw a half a cord of wood in these things at one time.)
There are some little quirks with them, most of the units are atmospheric , so the boiler has to be in the highest part of the heating system, or you will have to use a heat exchanger.
And being atmospheric you have to add water and chemicals or a regular basis.

Dave in NH

 

[beenthere]

Re: Outdoor wood boilers

What does "being atmospheric" mean?

My 'wood boiler' is kept at a pressure of about 14psi and I thought would be classed as "atmospheric", yet the boiler is not at the highest or the lowest point of the several 'heat exchangers' or radiant baseboard heat runs. It can heat by 'gravity' or by pumps (the way I use it now). I have had the same boiler unit for 20+ years. So far, so good.

Outdoor boilers are often fed with large quantities of green wood, which makes them pretty inefficient, because much of the wood energy is lost cooking (converting the water to steam) out the water. Appears they are run this way so they don't get too hot and the 'charge' of wood 'lasts' longer. Smaller quantities of dry wood would be more efficient, IMO.

 

[SPIKER]

Re: Outdoor wood boilers

atmosphearic means no pressure build up, an industrial boiler will build a lot of pressure 100PSI + and as the pressure build so does the water temp in the lines, untill steam is created, more pressure higher the steam temp... there is usually an open to th eoutside air for the water/boiler on standard residential heaters.

markm

 

[beenthere]

Re: Outdoor wood boilers

Thanks.
Mine isn't open. I have relief valves to 'relieve' the pressure if it gets too high. Don't have automatic fill, so I make sure that 'new' water added to the system is heated right away to 'degas' it, thus not having a problem rusting out the boiler.

Have to chase the air out of the system so no air traps are there to keep the water from flowing around the runs. Some bleeder valves help do that too.

 

[Egon]

Re: Outdoor wood boilers

An atmospheric water heater can be at the lowest point in the system as long as the water fill tank is at the highest. With the furnace at the lowest it could be gravity operated with no need for circulating pumps.

Egon

 

[rogdan]

Re: Outdoor wood boilers

I've done some internet research with mixed results but found little on TBN. The manufactures advances have been made in effeciency and durability. It would be reassuring to verify this with real world experience.

 

[Varmintmist]

Re: Outdoor wood boilers

Well, I havent had mine in for 5 years, in fact just starting on the second. Mine is a central boiler, that doesnt boil /forums/images/graemlins/grin.gif, it heats. I know 3 people personally that run these and they have both had then for longer than me and I have not heard any complaints.

Boiler is a term when it comes to these things. The temp in held between 180-190 degrees with a selonoid operated draft when its burning wood, it holds the water between 150-160 when it kicks to oil.

Yes you will burn some wood, if you dont have your own wood, I wouldnt get one. I figure I burned 4 cords last year, though I didnt have it in until Nov. I figure around 9-10 this year.

I heat 3 zones with mine. Garage, basement, and upstairs. the garage and basement are radient heat, the upstairs is forced hot air. the hot water and the upstairs are heated through heat exchangers.

Constant filling with water?? Nope. I think that I added water twice last year, and once when I fired it this year. Takes about 5-10 seconds to turn 2 valves on, then off to put the level back up to full.

www.centralboiler.com http://www.hydrofire.com/products.html

I have the 36, which heats around 3600 sq feet of well insulated house

 

[rogdan]

Re: Outdoor wood boilers

Thanks for all the replies,
Central Boiler is the brand I hear the most positives about and would lean that way. I have access to wood, just the work in cutting (which I enjoy). The reason I want an outside unit is the ability to heat another structure with the same unit.