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kill overheat with wood furnace


I recently try to repare and modificate an heating floor system with a oil and a wood furnace. Bolt on the same system. I made a parallel connection with the boilers and I put only one circulator on the return pipe. I didn't use a pump on each boiler because I was thinking that if the water pass constenly inside the oil furnace can help to kill the overheat when the wood groove working. The boilers zone had 1-1/4 cup pipe with a buffer tank set at 160F and then, I put an injection pump who feed the heating floor zone with an aquastat localisated on that zone. The heating floor zone is setting at 110F because it's all slab with ceramics. The system also have an indirect water heater and a big garage (36x40). I put a 1-1/4 pipe to connect the injection pump between the boiler and the heating zone because I was not sure how to do it. What can I do if to adjust easly and fastly if I oversive the injection pipe????? What should be the cheaply and easier way to kill the overheat if I still have on the boiler zone??????

Thank you,



  • Zman
    Zman Member Posts: 6,530

    or a picture...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,178
    only way to solve over heating

    you need a storage tank, 500 to 1000 gallons and the proper controls. The way you have it piped is not efficient or safe. You are risking over heating either boiler while it is firing as water is lazy and seldom does what it is not forced to do by either gravity or a pump.  
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • hot_rod
    hot_rod Member Posts: 14,738
    or worse

    you don't want the oil fired boiler keeping the wood boiler warm, as you will send some expensive energy up the flue.

    A buffer tank or an overheat zone are a couple options. Some installers use a section of fin tube, with a NO "normally open" zone valve to divert to dump zone when needed or when the power goes out and pumps stop, but not the fire.

    There are a number of ways to pipe systems with dual boilers. It depends on what you have for boilers, loads, space, and money to spend.

    This journal shows some piping options and the pros and cons.

    Wood heat is a lot more operator sensitive, they need to load the wood based on heatload and predicted weather conditions, it's hard to quickly shut down a wood fire, without completely putting it out.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zman
    Zman Member Posts: 6,530
    Great subject

    Hot Rod,

    I have seen that too.

    It was probably a good thing as the outdoor boiler had no glycol.

    As for the OP, I think he was a "One Post Wonder"

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
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