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Heating and hot water on together

Discussion in 'Plumbing and Central Heating' started by wrightsonm, 14 May 2019.

  1. wrightsonm

    wrightsonm

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    Currently my central heating and hot water go on and off together. I have an old glow worm fuelsaver 40b boiler which i think is 30 years old.
    It has one inlet and 1 outlet port.

    The system appears to be a gravity fed system (cold water tank, heating header tank, hot water tank without immersion element, 1 pump and no valves)

    There is a shower pump.

    It looks like it may have used to have a valve? Any ideas what this is?
    20190514_163845.jpg

    1. How can i get hot water without central heating? What do need to change?

    2. I was going to buy a hive central heating + hot water controller to replace the current one. Will this work based on q1?

    Here are a few more pictures of the system:


    20190514_163933.jpg 20190514_163912.jpg 20190514_163942.jpg
    Boiler below floor
    20190514_164029.jpg

    Many thanks
    Mark
     
  2. DP

    DP

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    Convert the system to Y or S plan should do it
     
  3. picasso

    picasso

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    Yes you can use hive with your set up, I think the "thing" in your pipework is some kind of filter but I have not seen one like that before.
     
  4. wrightsonm

    wrightsonm

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    I wondered if it was a failed valve thing as there were scorch marks behind it as if it had failed but that could be from a previous object or a gas torch.

    Maybe you are more right in it being a filter!
     
  5. stem

    stem

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    As it stands your plumbing doesn't allow separate control of the heating and hot water, so it is not suitable for control with Hive. Hive incorporates an integral room thermostat, (which I'm guessing you probably don't have now) so the Hive would also turn off the hot water whenever the house was warm.

    In the photo below, beneath the pump there is a 'T' and if the lower pipe goes to the radiators, then when the pump is running it will supply both the hot water cylinder via the horizontal pipe, and the radiators via the vertical pipe. This means that there is presently no way to automate the direction of the flow. Turning off the manual gate valve in the vertical pipe at skirting level will turn off the radiators during the summer.

    Pipes.jpg

    To allow you to automate control of your system, you will need to be able to electrically control the water flow from the pump to the hot water cylinder and heating system. The easiest way would be to install a 3-Port motorised valve where the 'T' is and making it what is known as a Y-Plan, as DP suggests.

    Here's a simplified diagram, showing how the 3-Port valve controls the flow to the radiators and hot water cylinder


    The whole system would need to be rewired from scratch though, and you will need a fair level of electrical competence to do it.

    Y-Plan-Hive.gif

    EDIT: Diagram tailored to specifically show connection to dual channel hive.
     
    Last edited: 15 May 2019
  6. wrightsonm

    wrightsonm

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    Ive had a quick look at 3 port valves and unless i am mistaken, it would appear the pipes would need to be rejigged to fit one since the inlet is from the pump on the side of the T, whereas all the valves i have seen have the inlet from the bottom of the T.

    Would i be better off going for an s plan, with 2 2 port valves so that the valves could both fit in the horizontal plane? Honeywell V4043H for instance?

    Thanks
     
  7. stem

    stem

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    Some rejig of the pipes for a three port would be required. It's not a major plumbing job, but probably for DIY a couple of two ports would be easier to install. That's how I originally converted mine at home.

    If in the future, you had a new boiler that required a 'pump overrun' (where the pump is controlled by the boiler and runs on for a few minutes after the boiler has gone off) with an S-Plan, a new bypass pipe and automatic flow regulator would need to be installed to provide an open circuit to allow the water somewhere to go. The advantage of the three port valve is that there is always one port open which will allow water to circulate.

    Having said that; if you have TRV's on all of your radiators then you would still need a bypass to be fitted when adding motorised valves. At the moment, if all of the TRV's were to close, water would still be circulating through the hot water cylinder. This would not be the case with an S-Plan if the hot water cylinder motorised valve were closed.
     
  8. wrightsonm

    wrightsonm

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    Thanks @stem for your advice. I do have 1 radiator without a trv. The isolator would turn off the heating circuit. I think a 3port is probably the better way to go. Think I'm going to consult a plumber on this one as im sure they would complete such a task waay quicker than i would!
     
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