Boiler Not Coming On Automatically

Discussion in 'Boiler Forum' started by amkazen, Sep 9, 2013.

  1. amkazen

    amkazen New Member

    Sep 18, 2009
    New Mexico

    I have a
    1) Crown Mega Stor Indirect Water Heater model #MS-40, Capacity: 40 gallons, Max Allowable Working Pressure: 150 psi, Temperature set to 170°, Watts Regulator Temperature & Pressure Relief Valve Model 100XL, Honeywell Aquastat 8148E Controller, Type L4006, Watts Regulator Expansion Tank, Model DET-12 M1, tank volume 4.5 gallons, and
    2) Crown Boiler Model XBF-150EID LP, Input 140,000 BTU/hr, Maximum WP 30 psi, Minimum Relief Valve Capacity 118 lb/hr or MBM, Temperature & Pressure Relief Valve Watts Regulator Model M3, Effikal International Flue Damper Model RVGP-KSF, unknown brand expansion tank

    The boiler supplies the hot water for both domestic purposes and radiant in-floor heat.

    The issue: sometimes we have domestic hot water and sometimes we don't. One plumber we have hired in the past said he had no clue what was wrong. Another plumber came up this past Friday, listened to my description of the problem and using only his eyes, no meters, no tools, nothing, pointed to the transformer on the Aquastat, said that was the problem, as the transformer was getting weak. He would have to have another plumber in his company come up to make the change and that cannot happen until next Tuesday, Sep 17. Ugh...we wanted it fixed sooner than that. We get hot water by manually propping open the switching relay on the Aquastat and my wife is tired of waking up in the morning to take her shower and maybe having hot water.

    The questions:
    1) Can a transformer get weak and only work some of the time, causing this problem?
    2) Can I replace only the transformer or does the entire Aquastat need replacing? At about $180 for the Aquastat it seems kind of expensive if the only thing wrong with it is a transformer, which appears to look like many other transformers.



    There are 6 zones to the radiant in-floor heating system:5 have been there since 2001, 1 added earlier this year by a plumber but is not active...
    Last edited: Sep 9, 2013
  2. Murphy625

    Murphy625 Member

    Jul 7, 2013

    1) Not likely. Transformers are solid state. They have no moving parts as they are just loops of wire and iron. They can go bad when they get too hot by melting internal insulation but I've never seen one magically repair itself.
    2) I'm not sure if the transformer is a replaceable component.

    1. Check transformer output with a meter. Its probably 120 in and 24 out.
    2. Monitor boiler when it calls for heat and see where the train of events stops.
    3. If the aquastat is in fact the problem, check the contacts on the relay and make sure they are clean. Low voltage, open air relays in dusty environments are a recipe for trouble.
    4. Double check all relevent interlocks like water level, high limit, flue damper, flame proving, etc.

    When the boiler calls for heat and fails to start, does the little switching relay activate (pull itself in)??? Or does it fail to even move on its own unless you do it manually?
    If it doesn't even move then you can ignore cleaning the contacts on that relay. If it does click and try to activate, it might be dirty contacts.

    The problem with calling a plumber is that they are not electricians and you have an electrical problem, not a leaky pipe.
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  4. Tom Sawyer

    Tom Sawyer In the Trades

    Nov 29, 2010
    If the transformer was weak, the heat would do the same thing. Either the wiring is wrong, which I suspect it is or there is a problem with the 4006.
  5. amkazen

    amkazen New Member

    Sep 18, 2009
    New Mexico
    Thanks for the tips. I will test it & observe it as you suggest.
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