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Vaillant heat only boiler + switched live thermostats + weather comp?

Discussion in 'Plumbing and Central Heating' started by notorious, 17 Nov 2020.

  1. notorious

    notorious

    Joined:
    30 Oct 2020
    Messages:
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    Thanks Received:
    3
    Country:
    United Kingdom
    Hello lovely people

    I have Valiant 428 heat-only boiler on S-plan Plus pipework.
    3 heating zones are controlled by 3 Nest thermostats via Switched Live Terminal 4.
    System water temperature is set at constant 45C.
    Lovely config.

    Now can I add Vaillant eBus Weather Compensation product (VRC series?)
    to this Switched Live controlled boiler?

    I want to have the flow temperature of system water
    to be dependent on outside temperature.

    Ideally, a product that sits in the boiler fascia,
    takes outside temperature from Internet via Wi-Fi,
    and sets the system water temperature automatically via eBus.

    Any Vaillant gurus here?
     
    Last edited: 17 Nov 2020
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  3. notorious

    notorious

    Joined:
    30 Oct 2020
    Messages:
    12
    Thanks Received:
    3
    Country:
    United Kingdom
    Replying to myself.

    Wanted to document the fact that Vaillant boilers will work with switched live thermostats (Nest),
    with hot water cylinder charging activation via switched live thermostats (Nest) <-- (click this link for detail)
    AND with weather compensation mounted on fascia (VRC module) to adjust hot water temperature depending on outside temperature.

    So:
    1. Your heating is running at low temperatures depending on outside temperature (I get great results with curve 1.25).
    2. When your hot water cylinder is calling for charging the boiler is going all the way up to 80C (and according to Nest's hot water schedule)
    3. AND all your thermostats in the house are switched live Nests

    Vaillant UK will tell you this does't work.
    It's BS -- everything works perfectly.

    All you need to do is to buy weather compensation VRC device that was manufactured at time when your boiler was released and mount it on boiler fascia.
    VRC module (in my example VRC 470) will regulate your hot water temperature and will allow to adjust all related parameters of the heating curve.

    Any questions you may have I'll answer here.


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