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Hot Water Cylinders and OpenTherm Control

I have an unvented cylinder hot water setup. I've jsut been investigating why my boiler is cycling a lot and realised that it's Eco setting, where it condenses best, is 68 degrees output temp, which was struggling to heat my cylinder to 65 degrees due to the small heat differential at the end of the heating cycle.

Solution is to set the boiler temperature higher. Which it doesn't like because that means lower efficiency and the radiators will be too hot to touch when the central heating is on.

I'm using the Extension Kit to control both hot water and central heating. By doing that I'm unable to set the Extension Kit to control the Boiler using OpenTherm. As I understand it, having OpenTherm control would let me set the output temperature to 80 for hot water and 65 for Central Heating. So can we have that please?

Along similar lines, the Hot Water side really needs to know the cylinder temperature and when the boiler is firing to be properly useful. Eg I'd like to know when the boiler was on, how much hot water is being used and add some more nuance to when the boiler is allowed to heat the water.

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  • A Tado cylinder stat is an excellent idea, not having one is a bit of a gap in their product lineup. It surely wouldn't be that difficult to create considering what they have already done

  • jelockwoodjelockwood ✭✭
    edited August 2020


    I totally agree, at a minimum it would allow a wireless cylinder stat linked to the Tado system whereas currently you have to use a traditional dumb wired cylinder stat. It could ideally also provide precise temperature control whereas traditional cylinder stats only provide 'call for heat' level control.

    However the lack of progress on providing a cheap simple room stat to override unreliable Tado Smart TRV sensors despite many, many votes (234 votes at last count) and requests does not lend a lot of hope.

    The crazy thing is that such devices would mainly re-use their existing technology and provide additional sales opportunities.

    PS. @PhilipJM you should add your vote to this request.

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