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Control Valve End switch

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cgw
cgw Member Posts: 42
in Thermostats and Controls
A small apartent building (10 one bedroom senior apartments) with a hot water baseboard system. There are two high efficiency boilers (with a indirect domestic water heater). The control inlcudes hot water temp. reset. There is a primary pump and each boiler has a secondary pump (plus the pump for the water heater).

Does it make sense to use the control valve end switch for a demand signel so the primary pump does not run all the time? I normally would not do this but it is a samll building (there is a control valve in each apartment plus a couple for common space).

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  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,022
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    Confused

    I have to make some presumptions here.

    By control valve, I think you mean zone valve.  When a thermostat calls for heat, it opens the zone valve and closes the end switch.

    And your primary pump is what circulates the water in between the boiler and apartments.



    If this is all so, don't you want your primary pump to be on when there is a call for heat?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,322
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    I think you have a constant circulation system

    It is designed for the system pump to run all the time. The unit control valves control the temperatures for the building. Do not monkey with it unless you are a pro willing to take the calls when the heat does not come up in old lady Leary's unit at 4 A.M. It is not the most economical way to control the system but the engineer never figured on that pump stopping so no provisions are in place to get the heat to run when an individual unit calls for heat.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • cgw
    cgw Member Posts: 42
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    Thinking out load

    Thanks for the input.

    The primary pump pumps between the boiler room and the building. Control valve is what you call the zone valve.

    Normally the primary pump would run constantly. A thermostat would open a valve and the zone would get heat. The boiler runs to maintaintain the loop temperature.

    If the building is small enough the end switch would start the boiler and the primary pump. The boiler would have to raise the loop up whatever it has dropped between calls for heat. (the boiler is low volume).

    This is only good in a small systems. Maybe never. Don't you do it in single family houses?
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