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Boiler power supply...EKO 40 with 1000 gallon storage

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by tuolumne, Feb 2, 2008.

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  1. tuolumne

    tuolumne New Member

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    Now living in VT, and building new home in VT
    There was some reference to this issue in the power failure thread. I was required (in think) in my previous home (oil boiler) to have a boiler shutoff switch at the top of the stairs, a heat activated switch above the boiler, and a service disconnect at the boiler itself. I have a NEC code summary, and the disconnect at the boiler is the only item referenced in there. What is prudent to incorporate into my gasifier electrical supply? There are no building codes or inspections in our town. The bank does not require a fossil fuel backup, so I won't have one at this time, but I want to plan the power and piping accordingly.

    So...what is the heat switch doing for me? A gasifier can't just switch off the fuel like the oil could anyway. Where can I find an (automag?) valve that will open in the event of power failure to dump heat? Does this device consume power 24/7 otherwise? For a dump zone I am picturing some fin tube on the ceiling in the basement. Is that typical? The disconnect at the boiler is no big deal. What about the top of the stairs? Again, I wouldn't bother shutting off the boiler as I run from the house in case of a fire. Copper is expensive. Some installation examples please....Thanks, this forum has been a huge help thus far.

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  2. jebatty

    jebatty Minister of Fire

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    Northern MN
    Search Google "valve automag" and you will find http://www.envirotherm.com/index.php?pg=boilersautomag

    My Automag is 24VDC and is powered by one of those small DC transformer power supplies I picked up at an electronics surplus store. It is designed to be always "on," that is, closed. When power goes off, the valve opens enabling a gravity dump loop. When my system is not operating, I shut off the boiler power switch and the Automag is on the same switch so it is off too. I will post more info later on current draw and my install drawing.

    My dump loop is finned baseboard sections. My Tarm dealer advised that these have a capacity of 500 btu/ft. I have 30 feet installed on the ceiling of the boiler room, which equals 15,000 btu's. The dealer also advised that the gravity loop should have a capacity not less than 10% of the rated boiler capacity. My Tarm is rated at 140,000 btu's.

    Hope this helps.
  3. Eric Johnson

    Eric Johnson Mod Emeritus

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    I have an automag, too. I don't know what the current draw is, but it can't be very much. Mine is wired into the circuit serving the wood boiler, so that you don't need a general power outage to open it--just a loss of power on that circuit. A little extra protection. I picked mine up on Ebay, but I had to wait until one came up--they're not as common as regular zone valves.
  4. jebatty

    jebatty Minister of Fire

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    Ditto, Eric. If power to boiler circuit fails, Automag cuts out and valve opens.

    Just measured Automag and transformer draws:
    Automag: 350ma @ 24vdc
    Transformer power supply: 12w, 16va, at 122vac

    Simplified install diagram:

    Attached Files:

  5. jebatty

    jebatty Minister of Fire

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    I just dealt with the issue of pump failure but no power failure with respect to the Automag. The problem is boiler overheat, no circulation, but since power does not fail, Automag does not open to activate dump loop.

    I added a surface aquastat to the boiler supply plumbing, connected the low voltage supply to the Automag to the aquastat, and set the aquastat at 210F. Now if at anytime the boiler overheats to 210F with power on, such as with pump failure, power is cut to the Automag and dump loop is activated. This does not affect the power failure activation of the Automag.
  6. Jersey Bill

    Jersey Bill Member

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    This sounds like I should install one of these.
    Why is the automag special ? could I use a ball valve with a normally open actuator. If I break power, the valve will open.
  7. Eric Johnson

    Eric Johnson Mod Emeritus

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    An Automag, as the name suggests, is an electro magnet holding a spring-loaded valve closed. When the power is cut, the magnet lets go and the valve opens, allowing the dump zone to thermosiphon. Any arrangement that does that will work.
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