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Outdoor wood boiler

MikeLMikeL Member Posts: 145
I will be connecting a wood fired boiler to an existing hot water heating system in a clients retirement home. Does anyone have a brand / manufacturer that they prefer ............


  • meplumbermeplumber Member Posts: 678
    Not a fan of the outdoor wood boilers.

    I realize that this is the customers choice, but I am not a fan of the outdoor wood boilers.  Recently, we have removed a couple of them.  In both cases the units were less than 5 years old and the customers were unhappy.  Both complained of high wood usage and a history of problems.  In both cases, we installed wood gasification boilers in the basement.  Wood consumption was cut in half, or more, and the customer is much happier.

    Be cognizant of circ sizing and selection.  Don't cheap out on your lines and insulation in the connecting lines between the OWB and the house.

    Good Luck.
  • James DayJames Day Member Posts: 185
    wood boiler

    A couple of companys make outdoor wood gasification boilers.   Central Boiler, Econoburn to name a few.  Both I have heard good things about.  As meplumber said don't cheap out on the underground pipe.  Uponor Ecoflex is a nice product.
  • Al LetellierAl Letellier Member Posts: 402
    outdoor wood boilers

    Be careful with your installation as mentioned in other posts. Be very careful to follow manufacturer''s instructions and document and photograph your installation. In my insurance work I have investigated 5 fires with outdoor boilers this winter....all but one were problems with the unit and the draft set up. All the cases involved had inadaquate storage and oversized boilers..they put out a lot of heated water and if the draft mechanism doesn't function properly.........

    The other concern I had is that unless your customer has an unlimited supply of free wood to burn, he will be burning a lot of his money....these units only shut down completely when they run out of wood. Otherwise, fuel is being burned even when the heat demand is met.

    My nephew has a great set up with a 1000 gallon insulated tank. He heats the tank with a wood burner and shuts down when temp is met, The water is used as needed and an oil boiler kicks in when needed. A completely manual operation on the wood side that really works and doesn't waste a lot of fuel.

    The tank is an old insulated stainless steel dairy tank bought at auction....need idea from a really smart young man.

    Good luck with your project.
  • EricAuneEricAune Member Posts: 431
    Check them all out

    I have been installing outdoor wood furnaces, that's right...they're not boilers because they are not pressurized, for about ten years.

    Firebox and controls are the key to one of these units lasting.  Do not forget that the type of wood and quantity are also major factors that will play heavily in their useful life span.  (Of course you cannot control what your customer burns but educating them is a good first step)

    In my experience the PEX is less important then the circulator and the piping arrangement near the plate heat exchanger.  Quality PEX and fittings, like Viega or Uponor will suffice easily, insulated of course.

    Oh, and be sure to stress to your customer that once they decide to use it they are married to it.  Back up or not, if they are going to get their value out of it they have to tend to it as if it were their youngest child...say goodbye to vacations and the like because its tough to get your neighbors to come over on those sub-zero mornings to stoke the firebox.  Like it or not, that's a reality.
    "If you don't like change, your going to like irrelevance even less"
  • James DayJames Day Member Posts: 185

    I agree with Eric.  Be aware on unpressureized outdoor furnaces that the installer isolates your existing boiler from the owb with a heat exchanger.  If you are using a pressured set up you don't have to but if you want to put glycol in the wood boiler to prevent freeze ups it is nice to have the glycol on the wood boiler end.
  • NRT_RobNRT_Rob Member Posts: 1,009
    I tend to feel

    that the unpressurized outdoor wood boilers cheap out up front to make the products look more attractive, but they have lots of hidden costs with constant circulation power draw, water treatment, cleaning and replacement of chemicals, heat exchangers they tell you that you don't need but that you often do, etc.

    I would go for a pressurized gasification unit every time, with unpressurized STORAGE and an exchange coil... and a cheapo backup for vacations.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Landry MechanicalLandry Mechanical Member Posts: 14
    edited May 2011

    My father in law is a dealer for Empyre. They have indoor and outdoor gasification  boilers. I have installed many of them and have great luck. My father in law went from burning 14 cords of wood to 8 when he upgraded to a gasifier. defiantly the way to go.

    -Ray Landry
    Landry Mechanical Oxford Ma
  • Terry OTerry O Member Posts: 60
    Eric... you are right on about most OWB's ...

    ....however the Econoburn is a pressurized outdoor wood boiler and is one of the few that can be refered to as a boiler. Great unit, we have been selling them for a few years now. Good company to deal with, great product and support.
    Terry O
  • IronmanIronman Member Posts: 3,533

    I tend to agree with most of what has already been said and would add my $.02 worth by recommending the Heatmor if you're looking for an outdoor wood boiler. They have a long and good track record if installed and maintained properly.

    We have sold and installed dozens with little or no problems if maintained correctly. We've also had correct several that someone else installed and the customer was ready to sue because, just as with any unit, they blame the appliance when something is wrong.

    The Heatmor is semi-pressurized: it has a weighted ball in the vent that relieves at 3psi. This keeps the unit sealed from the atmosphere to prevent oxygen diffusion and adds to the life expectancy of the vessel. It also has a water cooled door which prevents warpage and the water jacket is mounted on fire brick 8 inches above where any ash collects to prevent fire-side corrosion. It is also the cleanest burning stove that I've seen. If the fire is done right it will reduce everything to ash - no chunks of carbon - which is easily augered out.

    I would repeat what others have said: use a heat exchanger if you're connecting to a boiler. Don't pay any attention to the manufacturer's claims that it can be connected directly. And dis-regard their wiring diagram that shows using two thermostats to control the same system. I have a simple control package that I put together that works with any system with slight modification. Contact me if you are interested and I'll give you a diagram.

    One other note: these type of stoves are designed to burn large unsplit logs, not small kindling. That's alright to get it started, but small pieces have too much surface area and when a load of them is placed in the stove,  will cause it to smoke excessively.

    The key to purchasing any wood boiler is that the customer must have free or inexpensive wood available and must have a commitment to working with it.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • MikeLMikeL Member Posts: 145
    piping & control strategy

    Thanks to all of you for your replie's; I can always count on the Heating Help community for valuable information! My client is very energetic and  looking forward to using the wood he harvests as he transforms his 30 acre forest into a retirement compound.

    The house is heated by a Viessmann Vitodens which is connected to 3 hydro - air handlers and an indirect water heater. There is 2000 feet of pex in the basement and garage slab's, and staple up pex for the master bath and kitchen floor warming; we will be connecting this in the near future.

    I'm hoping the wood boiler manufacturer we choose will have competent tech support to help integrate the systems. I'm sure I'll be moving the indirect from the primary side of the low loss header and adding a buffer tank to store and deliver btu's as needed..................
  • IronmanIronman Member Posts: 3,533
    edited June 2011
    Don't Count upon the Manufacturer...

    For good tech support or info. Unless they are a regular boiler manufacturer, I've yet to see one that understood hydronics. That's why I posted the warning about their instructions regarding connecting their stove directly to the boiler and the two thermostat setup.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
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