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Zonal heating system question

Discussion in 'Plumbing and Central Heating' started by Sean Murphy, 1 Sep 2021.

  1. Sean Murphy

    Sean Murphy

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    Hi all,

    I have a very basic heating system that I would like to upgrade.

    Basically, it consists of a Oil burner (non condenser) and two zone systems (downstairs and upstairs), plus hot water tank (which is part of the upstairs zone)
    There currently are no thermostats except what is on the actual oil burner.

    It appears that the upstairs is controlled by a MV (and a timer clock). So, basically, you cannot have the upstairs RADs on unless the downstairs RADs are on. ( It is not a truly independent zone) and you cannot heat the hot water unless both downstairs and upstairs is on.

    I would like to install TRVs on the RADs, and then install a smart controller so that I can independently manage downstairs, upstairs and the hot water.

    Am I correct in assuming that in order to have a smart system I would need to get some pluming undertaken to split the zones and make them independent or am I missing something?

    Some more information:
    10 RADs downstairs
    8 RADs upstairs


    We are considering installing the Drayton Weiser multi zone system.

    Thanks in advance for any possible guidance,

    Sean
     
  2. Tricky-Dicky

    Tricky-Dicky

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    On a traditional heating system, in the first instance, you would need 3 separate zone valves, one for downstairs, one for upstairs and finally one for the domestic hot water. This does not seem to apply to your present system.
    Also 2 room stats one upstairs and one downstairs, and a cylinder stat to control the DHW.
     
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  4. oldbutnotdead

    oldbutnotdead

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    With the Wiser TRVs you don't need zone valves on the heating. What you do need is to replumb the system (slightly) so one of the 2 port valves is between cylinder and main pipes from boiler
    If you are installing wifi TRVs on every radiator you only need the 2 channel setup (1 heating, 1 hot water)- the TRVs will when calling for heat set the #1 line live (which will fire the boiler and pump up).
    The HW output needs to go to yr sole remaining 2 port valve (via a cylinder stat), the microswitch on the valve should then fire boiler and pump.
    Given the age of your boiler you might need to leave one radiator with no thermostatic valve on (as a heat dump for the boiler), might also need to arrange pump run-on.
     
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  5. Sean Murphy

    Sean Murphy

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    @Tricky-Dicky @oldbutnotdead .. thanks guys this is really useful information and has helped enormously.
    My only concern now is that deploying lots (10 or 12) Smart TRVs, will make my set-up too complex. I'll need to do some more investigations.
     
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  7. oldbutnotdead

    oldbutnotdead

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    If you remove the motorised valves then you need controllable TRVs on every radiator (otherwise you'll be heating spaces when you don't want to).
    Modern boilers controlled by Opentherm don't do motorised valves apparently but you don't have that problem.
    An option that might be worth looking at (you'd need the multichannel controller though, 2 heat and 1 hot water) could be to have the hot water zone (as above), one heating zone controlled by 2 port valve, normal TRVs, room stat somewhere (most likely downstairs), then all the upstairs rads on WiFi TRVs. So heating plan would be heat downstairs in a sort of conventional fashion, upstairs rooms set temps and times depending on room use (so spare rooms get enough heat to keep them aired but not full habitable heat).
    One warning- you have to assign the WiFi TRVs to one of the heat zones, you can't assign them to the hot water zone (so you can't cheat and have 3 heating zones).
    Programming the WiFi TRVs is simple, you can copy and paste from one to another (or to many).
     
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