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Wood Boiler, Combi and no storage

TJK500 Member Posts: 16
I'm working on a project that the home owner and general contractor want to use a wood boiler in conjunction with a combi boiler but we have no room for storage or buffer. The heating load for the house is 34,000 btu's and there is one bathroom and one kitchen. I would love to put a combi boiler and leave the wood boiler out of the equation and pay for some propane. My question is how should we go about making this mess work with no real direction. Sometime I think I should just walk away.


  • kcopp
    kcopp Member Posts: 3,815
    @hot_rod would know better but from everything I have heard you REALLY need to have some storage for the wood boiler. When that gets going you need a place to dump all that energy.
    If they really want to use the wood it may be best to supplement the home w/ a simple wood stove.
  • hot_rod
    hot_rod Member Posts: 15,004
    I wouldn't walk away. I'd run :)
    Have them get a small parlor stove for that size space.

    I've seen some small parlor boilers in Europe, a tiny HX to adder for some hydronic of DHW potential.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jamie Hall
    Jamie Hall Member Posts: 17,021
    Wood boilers (and furnaces, for that matter) have this odd tendency to get overenthusiastic on occasion, and you can't simply pull the switch. Therefore, you absolutely have to have some way to handle the excess heat. The usual way is to use a big storage tank (I'd make it big enough to handle a six hour, fully loaded, run from the boiler) and use that tank as a handy buffer for the whole system. The only other realistic alternatives -- which are rarely available -- is to have a water source with enough flow to handle that heat, or some way to actually physically dump the fire.

    If your clients don't want to put in storage, I'd thank them for their time and leave. Quickly.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • TJK500
    TJK500 Member Posts: 16
    Thanks for all the advice. I've sent them an email and told them i would install a combi boiler and all the system piping and controls but I was not interested in installing the wood unit or anything related to it.
  • GroundUp
    GroundUp Member Posts: 1,281
    There are dozens of wood boilers on the market that have their own storage built in. The make and model would need to be determined before anyone can accurately suggest a piping system. If the desired wood boiler is something with onboard storage, it's generally as simple as a plate heat exchanger and aquastat to make them coexist with a gas boiler or combi