Indirect Water Heater Not Calling for Heat

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by robertr4836, Feb 22, 2009.

  1. robertr4836

    robertr4836 New Member

    Feb 22, 2009
    New England USA

    I have an indirect fired water heater. A few weeks ago we ran out of hot water which had never happened before.

    I checked and even though the tank needed hot water the boiler was not firing. I reset the boiler and everything seemed to be fine.

    Yesterday we ran out of hot water again and the same thing had happened, the water heater was not calling for heat from the boiler. I reset the boiler again and it seems to be working but I want to get this taken care of.

    I figure it's the Honeywell controler that's the problem but I am very new to owning a house (had a condo before and I never had to deal with these things). Do I call an electrician, a plumber or the boiler service techs?

    Thanks for any response.

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    The sensor that tells the boiler to turn on may be bad or possibly the leads came loose either by getting knocked or just multiple heating/cooling cycles if they weren't tightened down properly.

    On most, you can test the sensor with a multimeter on ohms scale. The specs will say what the resistance across the sensor should be at any temperature. The resistance changes as the temperature changes. If the sensor is working, then the control in the boiler may be shot. If the sensor is not working, replacement is normally easy.

    A good HVAC boiler guy should be able to diagnose this, but you may want to try yourself. Don't do resistance checks with power on, and you really need to actually disconnect the leads to get an accurate reading.
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  4. kingsotall

    kingsotall Plunger/TurdPuncher

    Aug 17, 2008
    Hand copper part cleaned ready to go
    Flagstaff, AZ Sitting on an upside down 5 gallon b
    In these neck of the woods you're better off with a plumber. I should know, I work with him 4 days out of the week. There's a thread just started that could probably go have plumber vs. tinner for boilers.
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