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Simplex Multitherm

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by fguignard, Nov 17, 2011.

  1. fguignard

    fguignard New Member

    Nov 17, 2011
    South Eastern PA

    I have a late 70s early 80s Simplex Multitherm which I was told can burn wood. So far I've only used it with oil but would like to move to wood. I don't have a manual and I'm not sure how to proceed. Can anyone help? I'm attaching a couple of pictures of the boiler.
    Thank you in advance.

    Attached Files:

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  2. Jeremy Labrecque

    Jeremy Labrecque New Member

    Nov 22, 2012
    Hello, I have the same exact boiler and have started burning wood this year. My experience so far has been good with a few bumps in the road. The wood I started using is very very dry, it has been in the basement for 20+ years and burns quickly. So it is very easy to get the boiler too hot. My house has two heating zones. There is a switch on the right hand side that is used to put the boiler in oil mode or wood mode. I would assume yours is the same. Flip that switch the opposite way it is now and this will put the boiler in wood mode. the oil burner will not operate in this mode. (there is a chain actuated damper on the right side by what looks to be a tote cover. you should move that stuff away from the boiler because this damper need to be able to move free. To start a fire open the the top door after switching to wood mode. The lever you see in the picture is for the shaker grates which the wood will sit on top of, pulling this lever back and forth will allow the ashes and to fall into the bottom ash pan for cleaning. take a few pieces of crumpled up news paper put them in the fire box and stack some small kindling wood on top of the paper and light it. I usually open the bottom door to help get the fire going. Once the kindling wood is going good i will put 2 or 3 smaller pieces of wood on top and let them catch fire. then close both doors. I open the dial louver on the face of the bottom door to help keep the fire going (close this louver when burning oil)

    I then will go and turn up one of my zone thermostats up to 80+ which allows the zone valve to open and the circulator pump to run. to keep the boiler from getting to hot.. normal operating temp is 180 degrees at about 25 psi on the gauge. I find it will run a little higher when burning wood. If the temperature gets above 190 i will turn up the other thermostat to the second zone that helps dump the excessive heat to prevent the boiler from overheating and have the blow off valve go off and dump water all over the floor!. Hope this helps!
  3. maple1

    maple1 Minister of Fire

    Sep 15, 2011
    Nova Scotia
    In a safely controlled boiler arrangement & installation, manual intervention should not be required to prevent overheating. But I know nothing about this unit so am afraid I can't offer much else to help.

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