Outdoor wood boilers

rogdan · Oct 31, 2004

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 · Oct 31, 2004

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 · Oct 31, 2004

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 · Oct 31, 2004

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 · Nov 1, 2004

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 · Nov 1, 2004

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 · Nov 1, 2004

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 · Nov 1, 2004

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 · Nov 1, 2004

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 · Nov 1, 2004

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.

Varmintmist · Nov 2, 2004

Re: Outdoor wood boilers

BTW, mine is a stainless steel firebox, and a dual fuel unit. If you dont go dual fuel then you have to have a backup in the house, or never leave home in the winter.

Ther drier the wood, the less smoke and the longer the burn time. When you first fill it and the damper opens, it will smoke a lot. When the damper shuts, it will choke down to just a wisp because the air is cut off and it goes to a smolder. Once the moisture is out of the wood it will blow a nice blue smoke when the damper opens.

You can burn anything in them, but cured dry wood makes more heat per pound.

In cold weather I mostly have to fill it in the morning and after supper. When it is like it is now, it depends. Once a day when its 60 in the day and 30 at night. If the temp is 70 in the day and high 40's at night, it will go a day and a half 2 days. I mostly cut off the heat exchanger for the upstairs when its warm, because the radient heat in the basement floor holds the upstairs of the house at around 70. That increases my burn time because the heat is not bleeding into the ductwork.

If you do get one, insulate the incoming pipes and the manifolds if you go radient. Keeping the heat in the pipes will increase your burn time, and let your zones work. If you dont insulate the incoming pipes and the manifolds then you will leech heat into wherever the pipe comes in, making it HOT and increasing your wood usage. I posted pics before of the manifold and pipes coming in, I'll see if I can find then, or I'll just post them again.

rogdan · Nov 2, 2004

Re: Outdoor wood boilers

Varmintmist
With radiant floor heating how do you cool your home?
Or do you not use AC?

Varmintmist · Nov 2, 2004

Re: Outdoor wood boilers

Open the windows /forums/images/graemlins/grin.gif and ceiling fans.

The upstairs is forced hot air with a heat exchanger in the plenum. There is a spot for an A coil if I decide to add AC. That is why I went with forced hot air in the upstairs. The basement could be cooled if needed by installing a register or two in the duct. The basement is about 50% underground, so the temp shouldn't get real high there in any case.

rogdan · Nov 3, 2004

Re: Outdoor wood boilers

Thanks,
I was afraid that I could not add AC with the wood boiler heat exchanger(plenum?) in place.
We are considering a modular home with a FA system as part of the package. This could be held but doesn't lower the price much.

Varmintmist · Nov 4, 2004

Re: Outdoor wood boilers

Thats what we put up. A modular ranch with forced hot air. The thing is, what you save in plumbing with hot water, you spend on duct work for the air.

Where in West by God do you live?? My folks are down in Kenna, off 77, 45 min north of Charleston.

HammerFour · Nov 4, 2004

Re: Outdoor wood boilers

We have a Hardy Manufacturing outdoor wood furnace, it was on our property when we bought it. It took a bit of fixing to get it working, which seemed to be install issues, but now it works like a charm. When the indoor thermostat calls for heat the hot water is pumped to a heat exchanger in the plenum of our central ac/furnace and the fan blows the hot air thru the house.

Like others have mentioned it produces some smoke when heating the water but when dampered you rarely see a wisp of smoke come out.

- Tim

rogdan · Nov 4, 2004

Re: Outdoor wood boilers

Located in North Central WV, about 30 minutes NE of I-79 exit 119. I will be within 30 miles of Kenna tomorrow traveling for work.
Thanks TW,
I looked into the Hardy brand but they don't have dealers outside your area.

ernemats · Nov 9, 2004

Re: Outdoor wood boilers

I have a Taylor outdoor wood burner that I have had for over 10 years, and I have never had any problems with it. We had it at our previous home and when we sold the house the people who bought it did not want to bother with cutting wood so we moved it to our new modular ranch house. We have radiant heat in the basement and cast iron hot water baseboard on the main floor. I figure I usually burn about 6 or 7 cord a year. I usually fill it once a day at supper time unless it is real cold out, below 15 degrees for the daytime high. In the summer I usually fire it up once a week to heat the domestic hot water in the house.