Refining an S Plan system

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Tregrill
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Refining an S Plan system

Post by Tregrill »

Evotouch, S Plan system, 2 Heating Zones controlled by 2 wireless thermostats (Y87Rf2024) and relay boxes, HW controlled by ATF500DHW, Oil Condensing Boiler.

Is there a simple way to add better control of the boiler and pump which at the moment runs on/off on the Zone Valves Orange wires?

Thanks
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Richard
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Re: Refining an S Plan system

Post by Richard »

Well evohome was never designed to operate zone valves and switch live onto the boiler, so this was always a compromise.

Best way to do this is NO ORANGE WIRES WHATSOEVER... So a BDR91 controlling the oil boiler and primary heating pump directly (setup as a heating relay), Hot Water BDR91 controlling the opening and closing of the hot water motorised zone valve and then the relevant BDR91's attached to the relevant heating zone valves.
Home: 2012 Built Oak & Timber Frame Home (EPC Score 95 - A Rated)
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wghurley
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Re: Refining an S Plan system

Post by wghurley »

I have set up the S plan with zone valves. Works fine except when I call for heat the hot water valve is opened also, even though the hot water is OFF
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Richard
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Re: Refining an S Plan system

Post by Richard »

wghurley wrote:I have set up the S plan with zone valves. Works fine except when I call for heat the hot water valve is opened also, even though the hot water is OFF
Yep, like I said above, the core design of evohome when using HR91/HR92 Radiator Controllers was never to be used with zone valves on the heating pipework. If you look at PDF page 48 of the evohome Installation Guide (https://thesmartthermostatshop.co.uk/in ... tachment=7) you can see there is no zone valve fitted to the heating flow when fitting HR91 or HR92 Radiator Controllers to all radiators.
Home: 2012 Built Oak & Timber Frame Home (EPC Score 95 - A Rated)
Renewable Tech: GSHP, Solar Thermal, Solar PV & 20kWh Battery Storage
Smart Home Platform: Home Assistant, Shelly & Salus Smart Home
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