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  1. #1
    Join Date
    Sep 2008
    Location
    dallas
    Posts
    22

    Mixing valve - turning off pump issue

    this installation has a hot water boiler that has a mixing valve controlled by an Aquatrol device. also there are two alternating pumps that are on 24 hrs.

    during warm days, its clearly not possible to turn off the conventional cast iron boiler but in light of the mixing valve, it should allow an option to shut off the pumps when mixing valve closes; interested in thoughts on this issue (boiler is controlled by a DX-9100 from Johnson Controls) - the pumps cost about $25 in electricity to operate and real dumb to leave them on when there is no heat demand.

    the boiler has a circulating pump that effectively circulates water in a loop before it flows to the mixing valve.

    thanks

  2. #2
    Join Date
    Feb 2007
    Posts
    534
    The pumps need to run so the temperture can be monitored and control the operation of the mixing valve.
    If it doesn't go easy, you are not using a big enough hammer.

  3. #3
    Join Date
    Sep 2008
    Location
    dallas
    Posts
    22
    pumps it seems can be shutoff , but the mixing valve must be left partially closed when pumps are turned back on. otherwise the mixing valve opens up completely causing the boiler to be flooded with colder water.


    aquatrol device can be manually adjusted to slowly mix the water to avoid thermal shock.

    the boiler has a circulating pump so water flow is maintained around boiler when pumps are off.

    in light of this, does it make sense to turn off the circulating pump and manually adjust the mixing valve when its brought back on line.

    conventional boilers are so incredibly inefficient. a condensing boiler is the way to go as water temp can be adjusted alot lower and can be turned on and off.

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