3 way valve question

Discussion in 'Engineers' Talk' started by fiveO, Mar 13, 2019.

  1. fiveO

    fiveO New Member

    What is the best solution to my 3 way valve question:

    I am setting up a Solcrafte mains pressure (no pump!) batch solar heater 150L to feed during the hotter months the taps directly or preheat the cold supply to a AUER Edel Air heat pump with 100L tank.
    I have found thermostatic diversion valves sets such as ESBE VMD300 (3 way thermostatic divertor + 3 way thermostatic valve) which can be set to let >45C bypass the heat pump and go directly to the taps <45C water go to the heat pump.
    The heat pump will accept up to 65C via the "cold" supply and the divertor. The hot from the solar heater (max 95C) thus needs tempering with a 3 way thermostatic valve set to mix to 65C.
    The question I have if I stop and drain the solar there would be no water pressure (or hot water) at the hot inlet of the 3 way valve. Would the valve work to let just the cold water through?
    If it did not, what solution would you suggest?
     

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  2. MGW

    MGW Well-Known Member

    I think it is more down to where you live, daughter has a house in Turkey and solar water heating works fine, however father-in-law in North Wales and it was useless, there is a sensor on the panel and one where the coil went into the storage tank and if the panel was warmer than tank then the pump runs.

    In the summer the hottest the panel ever got was 28 degs C it did take the chill off the water when the central heating was not running, but to get hot water had to turn central heating on.

    It was all set up professionally, and when I realised it did not work, I assumed my father-in-law had turned it off so it had over heated, so we got a professional to re-pressurise the system and set it all up again, however no improvement, father-in-law died May last year, so the hot water was not being used, we would visit once a week to clean the house, and we had to use a kettle to get hot water.

    So further South than Chester may be water solar panels will work, but North of Chester bitter experience shows me it does not work.

    House was sold and all the solar gear was removed so the room where it was housed could be used for other things. So for 7 years it did nothing, however my father-in-law thought it worked, when they fitted it they removed the immersion heater, so the electric bill went down, but the water was being heated by the gas central heating boiler, and until he had the smart meter fitted he thought it was working, however on fitting the smart meter the pilot flame went out, and then he had no hot water.
     

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