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Any Idea on what this Combo Boiler is and how it operates!

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by mpilihp, Nov 11, 2008.

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  1. mpilihp

    mpilihp Feeling the Heat

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    Ok a friend of mine is helping his sister get the heating system in a house she purchased up and running. Its a Dumont DBW 130 boiler and operates on Oil and Wood. Please excuse the pictures as they are with a cell phone camera.

    [​IMG]

    It is a dual fuel unit, the oil boiler portion was completely clogged with cresote and would not vent out the chimney. The wood side is loaded from the top and has a vent pipe coming up to the top inside it and has a small square hole at the bottom going into the oil boiler portion. THen on the top of the oil boiler at the stack is a power vent/fan which runs on a timer switch. We are guessing that the fan/power vent is used to draw the draft of the wood side into the oil boiler in the square hole at the bottom connecting the two chambers and drawing it up into the flue pipe.

    [​IMG]
    See on the left the silver dome shaped over is the lid to the wood firebox.

    [​IMG]
    Here the cover to the oil side with the power vent on the top. Very wierd rig.

    He fired the unit up and the oil boiler was running but ran and ran forever. THe catch is this. In a sealed room in the basement is a HUGE tank, pressurized about 1000 gal im guessing. There are two circulators on the system. THe boiler is plumbed directly to this pressure tank, 1 1/4" in and out to is and back into the boiler with a circ on it. So once you turn the boiler on it runs and starts circulating the water in the tank trying to heat it ALL to 180 deg..

    [​IMG]

    There is a second circ pump we found inside this room with the tank. The this second circ is for the one heat zone in the house and it originates and ends in the tank so it must heat from the tank.

    Here are the expansion tanks
    [​IMG]

    So with that background the question is how to make this boiler heat this house without it costing huge $$s. My thought was to cut out and isolate the 1000 gal tank. Hook the heat zone up directly to the boiler and have the thermostat for the heat zone provide power to the boiler for the oil burner and to the circulator. When the zone thermostat is satisfied it will open and kill power to both the burner and circ. Ignore the wood portion completely as it appears to be a poor design as it was clogging the oil side of the boiler.

    ~ Phil

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  2. mpilihp

    mpilihp Feeling the Heat

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    Bump, alot of lookers but appears no-one has seen this boiler before??

    Best thoughts on how to isolate out the 1000 gal tank without flooding the basement? Sharkbite adapters go up to 1" from what I can see, I didnt measure what size the pipes were, if 1" Ill be all set but if its 1 1/4" then how to I cut into and cap off the tank without a flooded basement? There isnt any opening on the top to allow pumping it out, just the one on the end partway down.
  3. peakbagger

    peakbagger Minister of Fire

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    You have one of Richard Hill's University of Maine boilers. It was at the time, the most efficient wood boiler built and functioned as a gasifier. Most of them failed due to poor installation and no maintenance. The ones that are still running were usually "adopted" by the owner as the installers really didnt know how to run or maintain them. Its plumbed up like most folks would plumb up a gasifier boiler. The oil portion was designed as a backup to the wood and was not really intended for full time operation. The oil boiler will run for a long time as the design is to heat up the 1000 gallon tank and then heat the house off if it. That way the wood boiler could run at 100% load for an extended period of time, so it ran at maximum efficiency. I have seen his research papers explaining the concept in detail out on the web but cant find a link off hand. He sold the rights to Dumont and another company (Madawaska?) they "improved' it. His design did not have an oil gun. They were pretty robust units, I expect that as long as it holds pressure, it is rebuildable. I expect that the refractory is in need of repair or replacement.

    Just because its dirty and full of creosote, is not a reason to abandon the system. A wood system will require some more maintenance than an oil boiler but given the economics, its worth it. Who knows what was done to it previously. Like most gasifiers, it needs dry wood to work right, if the prior owner was feeding it wet wood, it wouldnt work right and would lead to the creosote build up in the secondary chamber. When they worked right, the logs burned from the bottom up and you could open the top cover to load it with no smoke. I have heard of some boilers of this design where the combustion blowers are all crudded up so they wont move enough air, clean off the inlet grilles and clean the blades on the fan and surprise, things start working correctly.

    Took me a bit but heres a link http://www.bioenergylists.org/stovesdoc/Hill/stick_wood_furnace.pdf


    If you dont want to revive the wood system due to the hassle factor, do yourself a favor and list the whole thing on uncle henrys and replace with an oil boiler. The oil gun that is there is not going to be very efficient and there is a lot of surface area to radiate heat which means the boiler will cycle more often. .There is no value in keeping the tank on line if you just use oil. Folks on the site would love to get the storage tank, but inevitably they were set in place when the house was being built and cant be removed readilly. If this is not the case and the tank still holds pressure, I think there are folks on this site that will remove for free. Many of the units used unpressurized oil tanks for storage and they rotted out long ago.
  4. Blevesque

    Blevesque Member

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    My uncle had one when he first built his house 20+ years ago. Did not like it from day one, never felt safe with it going. But he did say it made hot water like you read about. But the up keep, the scary rumbling when it was going and everything else that went with it was just not worth dealing with. He got rid of it 8 years ago for a Tarm solo 40.
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    "Inspect and Clean Chimney Frequently" is a rare piece of mfg honesty. It's also very good advice.
  6. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Maintained properly, those are some of the best boilers out there.

    As folks have said, though, the oil burner is solely there for backup, and running it non-stop is not a good idea. If you want to heat on oil, install an oil boiler.

    Joe
  7. mpilihp

    mpilihp Feeling the Heat

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    Thanks guys not sure what their gonna do but good to know what it is they have.

    ! Phil
  8. greg.ouellette

    greg.ouellette New Member

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    I just purchased a Madawaska boiler on Craiglist and it is off the original Dr Hill Design with improvements... I has 3 330 tanks... Very heavy unit but will take some work to get back up and going... Funny things is I emailed UMO and asked if there was a way to get in contact with Dr Hill and about an hour later the phone ring and it was him.. he was all excited and told me he will guide me thru the install... He is 92 years old... I will post pics of it.

    Greg



  9. peakbagger

    peakbagger Minister of Fire

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    Dick is a frequent guest/ co-conspirator with "tom in maine" on the Hot and Cold radio show on Saturday mornings in central Maine. I unfortunately am out of range from the radio show, but listen to it when I am in the area. I always wish it was available via the web, but I dont think there would be enough demand.

    I missed out on having Dick as a professor at UMO by a year or so, but he popped into various classes on occasion. I did get to go feed some wood to the industrial version he had built for a Maine Forest Service Nursery greehouse in Greenbush Maine once. If I remeber correctly it needed 45 pound of wood every 20 minutes when it was heating up the storage tank.

    The one thing to be aware of is that alot of the systems used oil tanks for water storage. Do yourself a favor and bring them direct to the scrap yard. Many of the systems got yanked when the tanks split a seam. I think Tom in Maine has a lot of experience replacing the tansk with his lined wooden tanks.
  10. tom in maine

    tom in maine Minister of Fire

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    "Lined wooden tanks"???

    Close, maybe 30 years ago, I appreciate the mention, regardless.

    The Dumont was the "Built like a Brick S***house" version of Dick Hill's boiler.
    They had fire tubes with turbulators and are certainly worth cleaning and re-using.

    The Dumont, Madawaska and Jetstream all used heavy refractory bases/tunnels which made them a bear to move.
    The refractory bases were also modular and simply rebuildable if necessary with either castable refractory or
    firebrick.

    Dick is currently working on a Russian fireplace for an apartment in his house that he rents to grad students.
    It will be well documented and will either get posted on one of our websites or Youtube, depending on how he
    documents it. It will be documented with lots of thermocouples and pictures.

    He states his longevity is "due to a half aspirin a day, a low fat diet and living in a state of constant outrage!"

    I suspect keeping busy with projects helps too.
  11. tom in maine

    tom in maine Minister of Fire

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    It would not be a big deal to install a three way valve that allows the boiler to go directly to the house when the oil is running. It would probably make more sense to rework the plumbing a bit
    to allow the wood or oil system to directly heat the house and then shunt over to the tank when necessary, more like current systems.

    This system is the kind of system that people here and elsewhere are spending tens of thousands of dollars on. It functions as well as most current technology.
    It appears to be all there and sounds like it just requires some cleaning and replumbing.

    These were very expensive back in the day (which was the late '70's through the mid 80's).
  12. mikeyny

    mikeyny Feeling the Heat

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    Dick Hill must be one awesome dude!!!!!I would love to meet him
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