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Thread: Total house refurb, heating system advice needed.

  1. #1
    Automated Home Lurker
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    May 2018
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    Default Total house refurb, heating system advice needed.

    Hi all, I am doing a total house refurbishment and the builder will put in a new heating system from scratch soon. I am planning the following and since my builder is not very familiar with EvoHome I would like to get come advice:

    1, all upper floors will have radiators fitted with HR92, perhaps except one bathroom where I will leave the towel rail fitted with a manual TRV.
    2, whole groundfloor will have wet UFH, divided into 3 zones, controlled by a single manifold and the evohome underfloor control.
    3, unvented cylinder to store hot water.
    4, using S plan.

    Can you please advice which boiler, cylinder to buy that work nicely with EvoHome?

    Also my understanding is that the radiators will be controlled by HR92, while HW and UFH will each be controlled by a zone valve, what will happen if all three or two of them (radiators, HW, UFH) request heating demand at the same time, what will happen? Will there be some kind of priority automatically managed by EvoHome?

    Thanks very much.

  2. #2
    Automated Home Legend
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    Jul 2014
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    Default

    In an S plan there is no priority as such unless you wire the zone valves as such. Also with Evohome, you don't actually need an S Plan you can just have a single zone valve for the HW and the CH on a boiler loop. Even everything demands for heat, hot water will flow everywhere but at the HW target flow temp. Which in most instances is the same as the CH target flow temp. Evohome does not yet support two max flows.

  3. #3
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    Thanks Bruce.

    Does that mean the radiator will be super hot ? I would imagine normally the DHW has a much higher flow temperature than CH. At least that the setting in my vaillant combi boiler.

    If the whole underfloor heating is just one zone , can I just use a BDR92 and a zone valve instead of the expense underfloor controller? Any drawbacks ?

    Any comments on boiler and cylinder?

  4. #4
    Automated Home Legend
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    If the entire ufh zone is a single open plan area that cannot be closed off then I would definitely run it as a single zone and then you just need a Y87RF kit which comes with a room stat and a BDR91. It's really that simple. The moment you have to split a manifold into multiple zones the expense is quite high because each outlet on the manifold will need an actuator.
    The one boiler that I have heard about that can do 2 temperatures with Evohome Opentherm is the Intergas. You basically use a BDR91 to trigger the HW cycle and use Opentherm for the CH side of things. And / Or you can stop the HW going to the CH circuit by using the BDR91 in a HW priority configuration where the CH closes each time the HW opens.

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