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Are steam boilers cold starts?

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itzasean
itzasean Member Posts: 71
in Strictly Steam
So I was reading a bit on cold start boilers for forced hot water and it had me think does my steam boiler only start when the Thermostat on the wall tells it to or do they still cycle to keep the water at a certain temperature but not enough to produce steam ? I have a gas burnham independence boiler . 

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  • JUGHNE
    JUGHNE Member Posts: 11,072
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    It would be a cold start.
    The wall tstat controls the starting and stopping.
    Now your pressure control may stop it if it reaches the pressure setting, as the pressure drops then the boiler fires again, this cycle will continue until the wall tstat is satisfied.
    Short cycling because of the pressure control in not favorable, you could need more steam main venting, pipe insulation or the boiler is too large. (often the case) Or if it is a mild temp day.

    However being cast iron, it may still be warm for the next tstat call for heat.

    But if you heat your domestic water with the steam boiler, the boiler will fire up just for the water heating. It should not get hot enough to steam.
    itzasean
  • itzasean
    itzasean Member Posts: 71
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    Why would it start up again when the pressure drops if the temperature in the house is at or above the thermostat setting? 
  • JUGHNE
    JUGHNE Member Posts: 11,072
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    The tstat is the first control in charge, the pressure control is next in line.....maybe some other safety switches...but most likely the pressure control will do the cycling while the tstat is calling for heat.
    It would only restart on pressure drop if the tstat is not satisfied.
    It may be cycling on the pressure switch and you are unaware of it.
    itzasean
  • mattmia2
    mattmia2 Member Posts: 9,716
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    If it does have a coil for DHW or has a hot water heating loop, the controls for that could be set up as either cold start or warm start although warm start is far more common because it is simpler, it is just an aquasstat in parallel with the thermostat that keeps the boiler at the temp needed for the hot water system all the time.
    itzasean
  • gfrbrookline
    gfrbrookline Member Posts: 753
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    Does your steam boiler also heat your domestic hot water? If not the short answer to your question is your boiler does cold start if the TStat does not call for heat over a long period of time.

    If it does also make your DHW it should have an aquastat on it that holds the water at around 160.
    itzasean

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