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Memco 100W will this get the job done

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by MJG, Nov 19, 2012.

  1. MJG

    MJG New Member

    Joined:
    Oct 9, 2012
    Messages:
    2
    I'm looking for some advice from you guys for installing a wood boiler. Need to get one in this winter, and looking to see which one is right as well get some technical advice. I have a 1600 sq ft. house that is poorly insulated. Currently have a woodstove in the basement with a 8" dedicated chimney. The stove isn't cutting it. I'm looking to start with something used and eventually buy new if it works out. There is a Memco MW100 for sale in my area and I'm wondering if that is right for me. I currently have forced hot water with a tankless set-up. My goal is to have a burn time of about 6-10 hrs, which I know is optimistic, and I'd like to heat the DHW of the boiler as well. Will I need a dedicated heat exchanger for that, or by just hooking into the return on my oil burner will keep the tankless water hot enough. Don't know enough about oil boilers to know if that will heat the tankless DHW or not. I also am wondering if the boiler will produce to much heat and I will need some sort of heat dump, or some way to get rid of excess temperature if it gets too hot. Not sure what will happen if the power goes out as well. The memco is a 120,000 BTU unit, not sure if it is too big or not. I am trying to avoid the pressurized hot water storage design as I would like to keep costs down. Any suggestions on proper size, DHW hook-up, heat dump. Thanks.

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  2. BoilerMan

    BoilerMan Minister of Fire

    Joined:
    Apr 16, 2012
    Messages:
    1,604
    Loc:
    Northern Maine
    Welcome!! I've installed a Memco at my FIL's house. First off, the btu rating on a wood boiler is somewhat of a crap shoot. They have no way of telling what kind or how much wood you load in it, as well if it's properly seasoned. The 120Mbtu will be fine, be aware though that this is what is refferred to as a "smoke dragon" and you'll find out why. You need to keep the stack (stove pipe) temp at least 300F to get any kind of heat out of a smoke dragon, trust me on this I heated my house for years with one. Get a cheapo magnetic sotve thermometer and adjust the draft to get the 350F mark. You will not get long burn times this way, but it will creosote up like crazy if you don't. Expect 4 hour burn times if run properly. Longer are possible but it will be too cool and the black tar will run down the inside of the firebox and the chimney.

    Heating water: It's my opinion and I've done lots of research is to use a 40 gal electric water heater with a sidearm heat exchanger. This is cheap, and is two fold, in the summer it's just an electric water heater (no boiler fireing) in the winter, it's an indirect with the sidearm and the electric can be turned off. This is the cheapest way to heat water at the lowest install cost.

    Heat dump: An aquastat set at something like 195F on the wood boiler connected to the largest zone in your house (either ZV or circulator). When the boiler gets too hot this tells that ZV or circulator to over-ride the thermostat and turn the heat on.

    Hope this helps
    TS
  3. lotawood

    lotawood Member

    Joined:
    Dec 11, 2011
    Messages:
    28
    Loc:
    montana
    I had a memco 100. I didn't like it. It had short burn times due to short wood.

    I think it could be compared to a 100-120 kbtu outdoor wood boiler, that is indoors and a small firebox.

    I think it might have been more impressive with coal, which it was rated for. Coal is hard to come by in this area, even though there are train loads of it nearby.

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