# Wood add on for a buderus oil fired boiler



## middcrossrx (Jun 9, 2008)

I currently heat my home (2200 sq. ft. of old Vermont farmhouse) with a Buderus oil fired steam boiler. I have been looking for a wood fired add on for the furnace. I have had a hard time finding a suitable furnace add on. I have plenty of room in the basement to add the furnace and store wood, and would rather not have to deal with an outdoor wood funace (Vermont regs. make it tough.)  Thanks!


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## mysticfalcon (Jun 10, 2008)

We use a lot of Logwood and New Yorker add-on boilers.  Ive always had good luck with them.  I'm putting a biasi in my house in a couple weeks to try one out.  All are good options.  Where are you in Northern VT?


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## Eric Johnson (Jun 10, 2008)

I would second Pook's concern. Steam and hot water systems are not compatible, and nobody (that I'm aware of) makes a wood-fired steamer.


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## middcrossrx (Jun 11, 2008)

Sorry for any confusin. The furnace uses steam to heat our radiators throughout the house. My questions was not about adding a hot water boiler- but an add on steam boiler. I was not sure if a wood add on that creates steam- like the current boiler- exists. I looked at the logwoods, but they only seem to work with hot water boilers, not steam. Any suggestions you have would be great. Also, I am in the Burlington area of Vermont. Thanks in advance!


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## Eric Johnson (Jun 11, 2008)

Unfortunately, as I said, nobody that I'm aware of makes a wood-fired steam boiler. You might try Gary Switzer of Dundee, NY, who custom-fabricates wood-burning equipment. He might be willing to make one for you.


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## middcrossrx (Jun 11, 2008)

Thanks for the suggestions. I was afraid of that. Would any of you consider just adding a woodstove in the main/ living room? We have a pretty open floor plan, and the way the house is set up (front and back stairwells) the heat is pretty evenly distributed upstairs. My fear is that the pipes in the basement may freeze if I am supplementing too much with the wood. My family tends to spend most of our time in the living room, kitchen, and den, all of which will be easily covered by a mid sized stove. The thought was wood heat during the day and oil at night (when the thermostat is turned down anyway.) Our basement is full, half poured concrete, and half pointed fieldstone. It does not get that cold, even during the worst nights, but I just would not want to have pipes bursting mid winter. Thanks for all the help so far.


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## WoodNotOil (Jun 12, 2008)

My house had a steam system when I moved in.  The house is 60 years old and not well insulated.  A new steam furnace was put in just before we bought the place.  What I did was converted the steam boiler to hot water and added a Tarm gasifier.  I retrofitted radiant in the first floor and ran baseboard through the house.  (I actually installed the radiant and baseboards while still using steam and in two days disconnected the steam, converted the furnace and was hydronic by the next day)  I am now heating entirely with wood, DHW too.    Once I add storage this summer, I will only burn oil as a backup.  It was worth the money and time!  

If you go with a wood stove, I would suggest putting in floor registers so heat gets to the upstairs rooms.  Good luck!


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## EWD1 (Jun 12, 2008)

Woodgun claims some boilers can be ordered W/ low pressure steam.


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## webbie (Jun 12, 2008)

Best bet is to convert the system to hot water as stated above.......


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## NHFarmer (Jun 12, 2008)

I too have steam heat and looked at options for wood burning steam boilers.I found nothing that would work.If you could find someone that does make a boiler you will still have problems with proper elevations for the steam as well as proper pitch on returns.This will prove to be difficult having two boilers.I have bought a Tarm and am going to convert over to FHW.I think FHW is your best bet.


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## middcrossrx (Jun 12, 2008)

Thanks for all the input. How would I convert my existing furnace to FHW? I think the wood gasifier would be great, but I am not sure how to start.


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## WoodNotOil (Jun 13, 2008)

In my situation the radiators were 60 years old and a one pipe system.  Needless to say. . .  I sold them by the pound when I was done setting up the new system.  There was a conversion package available for my steam furnace.  There is not a lot of demand for steam boilers so these companies modify a hot water one to begin with.  That is why there are conversion packages.  It also came with a domestic coil.  If yours is an older boiler, I am not sure if there is a conversion kit for it.  You could contact a heating/plumbing supplier in your area or find a local rep for that brand.


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## jdurant (Feb 6, 2009)

ahs make a multi fuel wood coal boiler with steam fittings. go to there website and check it out.


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## bupalos (Feb 6, 2009)

I think the main question is whether the radiators would produce enough heat on water rather than steam. Probably yes- it would just run more on lower temp fluid and be a little less responsive. The system itself would flush out pretty quickly I think if you just ran a few thousand waste gallons through it. And you'd want to build such a system with storage or at least buffer for sure. Both the wood boiler and steam boiler heat your storage tank, storage tank feeds your rads.


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## BrownianHeatingTech (Feb 6, 2009)

middcrossrx said:
			
		

> Thanks for all the input. How would I convert my existing furnace to FHW? I think the wood gasifier would be great, but I am not sure how to start.



First, do you know for a fact that you have a steam system?  I'm not meaning to be insulting, but I have dealt with folks who thought they had steam because they had radiators when, in fact, the system was already a hot water system.

If you do know that it's a steam system, then the first thing to determine is whether it is one-pipe or two-pipe steam.  A one-pipe system uses a single connection to each radiator, whereas a two-pipe system uses two.  Steam can flow along the top of a pipe while water flows back along the bottom, which is great for installation simplicity, but is not compatible with a hot water system, where you need separate supply and return pipes.  So, if you have a two-pipe system already, a lot of work is avoided.  If you have a one-pipe system, then a second set of pipes (typically pex instead of metal) is installed.  This can raise issues with whether there are appropriate fittings on the existing radiators, which would require an examination of the radiators by an experienced heating contractor, in most cases.  And, of course, when dealing with old radiators, there's always the risk that a plug will snap when you attempt to remove it in order to connect the second pipe.

The next potential issue is radiator size.  Steam is hotter than hot water, obviously, so a smaller radiator can produce the same heat when using steam.  Or, conversely, that radiator might not produce enough heat when used with hot water.  Mitigating this is the fact that many older systems were oversized when they were installed, and/or the house has been upgraded since the installation, so the radiators may be well more than big enough to do the job.  There are calculations that can be done, but without knowing the exact situation regarding the insulation value of the existing structure (which is usually the case with older homes), those calculations may not always end up being very accurate.  If practical, the best solution is usually to try it and find out.  If some room seems to be a few degrees cooler than it should be, then it may need more radiation (a larger radiator, an additional radiator, or some other supplemental heat source, like baseboard or a fan unit).

In any conversion, care needs to be taken to install filters to remove particles from the water.  There is a lot of sediment in most existing steam system piping, which tends to just sit there.  When you start pumping hot water through those pipes, it can "wash" that sediment back to the boiler and pumps, doing substantial damage.  So strainers and sediment separators should be installed to capture and remove that sediment.  Initially, they need to be cleaned frequently, but as time goes on the sediment is captured and removed, and the strainers and separators will go longer and longer between cleanings.

*Alternatives:*

As others have noted, the biggest alternative to this is to simply install some other heating system.  That can involve leaving the steam radiators in place, as backup, or completely removing them and freeing up that floorspace.  Often, that decision is made based upon the aesthetics of the situation (a lot of folks like the look of the old radiators), or upon the available space (removing radiators can free up usable floorspace in many cases).

Options for other heat delivery methods include baseboard (inexpensive, but not very efficient), radiant (heat up the entire floor or ceiling, which then heats the room - typically more expensive than other methods, and many not work with thick flooring), or forced-air.  A heat exchange coil (similar to an automobile radiator) can be installed in the air ducts, allowing hot water (from a gasification boiler, in your example) to heat the air.  If the radiators are being removed, the locations where they sat are often workable for ducts (at very least on the first floor).  Back-up can be as simple as an electric coil installed in the ductwork, or an oil- or gas-fired furnace, or a second boiler which can also deliver hot water to the heat exchange coil in the duct.  There is also the option of adding air conditioning with forced-air.  High-velocity systems using small (4") ducts can make conversions quite practical, but running ductwork is still more involved than running pipe, and forced-air systems generally draw substantially more electrical energy than forced-water systems, since fans are less efficient than pumps.

Ripping everything out and installing baseboard is probably the cheapest possible conversion.  Converting the existing radiators or installing forced-air would tend to duke it out for the mid-range on price, depending upon the specifics of your actual house.  A radiant installation would tend to be the most expensive (although also the most efficient and, in my opinion, the most comfortable).

Of course, we can get further afield of that, and talk about hybrid systems.  For example, it might work best for a particular application to install a forced-air conversion for the first floor, and convert the radiators on the second floor (since it's easier to snake pipes up, versus running ductwork).  There are also a variety of terminal units which use a small fan and heat exchange coil to produce hot air for just one room.  These can be mounted on or recessed into a wall, floor, or ceiling, or installed in the kickspace under a cabinet.

So, there are a lot of options.  What works best for any given structure will depend upon the specifics of that structure, and the budgetary concerns of the owners.

Joe


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