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motorised valve purpose

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  • 17-07-2019 11:11pm
    #1
    jimmycrackcorm
    Registered Users Posts: 14,330 ✭✭✭✭


    I have a combi gas condenser boiler for heating water / rads. During the summer I use the manual lever to shut off flow to the radiators as I only need hot water.

    In the hotpress attached to the tank is a Danfoss HA2 2 port motorised valve feeding the pipe to the Radiators (turned off ) and the hot water.

    I'm not sure if this valve works as When the lever is on then both the hot water and heating timers heat the radiators regardless.

    What's the purpose then, of such a two port valve? Unless I'm mistaken that there is another separate hot water flow to the taps that is always on and this should really be stopping the flow to the central heating and just isn't working?

    TLDR - what's a 2 port motorised valve from the hot tank normally used for?


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    #2
    Cerco
    Registered Users Posts: 2,034 ✭✭✭Cerco


    Perhaps the motorised valve is controlled by a thermostat on the tank. So when the tank is cold it shuts off the rads. When the tank reaches a set temperature then the rads are switched on.
    Just guessing..


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    #3
    DublinDilbert
    Registered Users Posts: 5,367 ✭✭✭DublinDilbert


    jimmycrackcorm wrote: »
    I have a combi gas condenser boiler for heating water / rads. During the summer I use the manual lever to shut off flow to the radiators as I only need hot water.

    I

    If you have a combi boiler, you don't have a hot cylinder / tank. With a combi it can heat water and raditors separately so no valve required. You possibly have a standard boiler.


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    #4
    jimmycrackcorm
    Registered Users Posts: 14,330 ✭✭✭✭jimmycrackcorm


    DublinDilbert wrote: »
    If you have a combi boiler, you don't have a hot cylinder / tank. With a combi it can heat water and raditors separately so no valve required. You possibly have a standard boiler.

    There are separate timers to hear up water and radiators separately and both a wall and hot water tank thermostats to determine the temperatures for both.

    My guess is that this motorised valve should actually be closing off the central heating when the got water gets triggered. I'm presuming the idea is that if you need hot water for a bath or shower that this gives that priority.


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    #5
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    It would be unusual but not unheard of to have a combi boiler feeding one or two taps and a hot water cylinder as well, (i'v seen one in the UK a few years ago and I think it was only ~ 15kw output), when not supplying hot water directly it changes over to radiator heating (as all combis do) and as stated above, a motorized valve used in conjunction with a cylinder stat can also feed the hot water cylinder.


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    #6
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    jimmycrackcorm wrote: »
    There are separate timers to hear up water and radiators separately and both a wall and hot water tank thermostats to determine the temperatures for both.

    My guess is that this motorised valve should actually be closing off the central heating when the got water gets triggered. I'm presuming the idea is that if you need hot water for a bath or shower that this gives that priority.

    Just saw your post. That set up looks more like a conventional system boiler or a combi boiler being utilised as a system boiler. If it is giving instant hot water to one or more taps then if you turn both the wall stat and the cylinder stat to minimum and then open the hot taps and you are getting hot water and the boiler doesn't fire up then it is not operating in combi mode.


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    #7
    jimmycrackcorm
    Registered Users Posts: 14,330 ✭✭✭✭jimmycrackcorm


    John.G wrote: »
    Just saw your post. That set up looks more like a conventional system boiler or a combi boiler being utilised as a system boiler. If it is giving instant hot water to one or more taps then if you turn both the wall stat and the cylinder stat to minimum and then open the hot taps and you are getting hot water and the boiler doesn't fire up then it is not operating in combi mode.

    I think I might be incorrect to suggest is a Combi boiler then. There is no instant hot water in any case. The boiler is an ideal classic FF250.

    So I'm really thinking now that the boiler is driven by the respective timers and thermostats for water / CH and that the intention of this motorised valve is to block the flow to the central heating of only the water is triggering

    In which case I think either the valve or actuator need replacing as I can't see any difference


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    #8
    John.G
    Registered Users Posts: 3,472 ✭✭✭John.G


    jimmycrackcorm wrote: »
    I think I might be incorrect to suggest is a Combi boiler then. There is no instant hot water in any case. The boiler is an ideal classic FF250.

    So I'm really thinking now that the boiler is driven by the respective timers and thermostats for water / CH and that the intention of this motorised valve is to block the flow to the central heating of only the water is triggering

    In which case I think either the valve or actuator need replacing as I can't see any difference

    You probably have a 15kw system boiler. It seems a bit strange to use ONE 2 port valve to control both CH &HW, normally where one motorised valve is employed its actually a 3 way valve (y plan) where you can have either HW or CH or HW&CH as desired.
    https://www.plumberparts.co.uk/advice/heating-systems/y-plan-heating-system


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