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Thread: Rads upstairs getting hot when hot water is on - gravity fed

  1. #1
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    Default Rads upstairs getting hot when hot water is on - gravity fed

    Hi - am new to this forum so please bear with me

    I wonder if any of you can help - I have a gravity fed system (Sime Superior 80 boiler) and when I switch the hot water only on, the rads (upstairs mainly) get warm/hot. I have checked the three port valve and it is changing to the correct positions when the hot water and heating is on. Can someone point me in the right direction please ?

    Thanks very much

    Chris

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    Forgot to say that some of the rads are getting air in the system so am having to constantly bleed the air out of the rads.

    Thanks

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    how long has it done this,
    between the pump and the diverter valve there might be a by-pass with a gate valve on it ,is it open,if so close it.

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    Hi - thanks for your response.

    It has done this for quite a while. I cannot see a diverter valve between the pump and the diverter valve, however, there is a pipe going upstairs from the oiler (I think its the flow pipe) which has some kind of valve on it - how can I tell if its open ?

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    are we sure its air in the rads,the next time you have to bleed them have a lighter ready and try and light the air if it lights it's not air,your system needs some inhibitor in it.
    if that then solves the problem with the air,then i would say the 3 port valve is passing.

    if it turns out that the air will not light then it is air,getting into the system some how,

    how hot are the rads and hot water,if there overly hot then the boiler stat may have gone,

    if not then i'm thinking the hot water return could be blocked,

    does the hot water from the diverter to the cylinder go into what is called a "hot rod" that is. the two pipes go into the top of the tank, or do they go into the side.

    hope this makes sense

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    Hi - having attempted to light the air - it did infact light - quite a long flame too! So I will put some inhibitor in ASAP!

    Regarding the second point, the pipe going into the top of the diverter valve is coming out from the side of the cylinder. The pipe going into the middle of the valve is coming out from the loft and the one coming out the bottom of the valve is going straight down. Not sure if this makes sense ?

    Thanks once again!

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    yes makes sense.

    i would suggest now that the diverter is passing to central heating slightly when on hot water only,

    do you know what make it is?

    are there any gate valves to isolate the diverter?if so you might be just as well turning the one off that is on the central heating side, in summer.

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    It is a Honeywell Sundail Y plan 3 port valve. I dont think there are any gate valves to isolate the diverter. Is there a way of checking if the 3 port valve is slightly on central heating whilst on hot water only ?

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    you could put the clock on water only and feel at pipe coming out of the 3 port going to the heating,

    or put the clock on water and heating , turn the room stat down and feel the pipe

    it will get warm for a couple of foot after the valve but this is normal,

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    Default Re: Rads upstairs getting hot when hot water is on - gravity

    Hello,

    Apologies for the long delay in responding...I have checked the three port valve (it is a honeywell V4073A1039) and when I switch the mains off, the lever moves with resistance (e.g. I can hear the motor winding), however, when I switch the mains back on the lever is completely loose - and moves freely. Does this indicate that the valve or actuator is faulty ? It only moves automatically when H/W comes on but not for Central Heating.

    Thanks

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