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Thread: Smart TRVs without smart boiler controller

  1. #1
    Automated Home Jr Member
    Join Date
    Dec 2015

    Default Smart TRVs without smart boiler controller

    Can anyone explain the consequences of using smart TRVs with vs without the smart system also controlling the boiler for heating (for a system that is only being used to zone each room)?

    I'm thinking about switching my house to smart heating and I'm trying to work out if I ought to get a system that includes boiler control. Some systems (such as Eve) seem to be intended to work without this; with others, it seems to be optional (eg, you can control Hive TRVs with just a Hive Hub or Tado TRVs with just their internet bridge); and with yet others I think boiler control is compulsory (eg, I think Evohome requires this, though I could be wrong).

    I work from home so our house is rarely empty, other than when I'm walking the dog, which isn't long enough to make it worth switching the heating off. So, for me, the main benefit of smart heating would come from setting different schedules and temperatures for each room. When I'm the only one in, I just need my study and the kitchen warm. Bedrooms only need to be warm late evening and early morning. Lounge only evening.

    The CH piping is a single zone. I assume that if I went for a system that did not control the boiler when a TRV wants heat, the boiler would still be controlled by the timer in our boiler cupboard and the wall thermostat in our hall. Presumably I'd need to make sure these were both set so the boiler was always able to supply heat whenever any smart TRV wanted heat? So, I'd need to set the timer to be on from dawn to bedtime and the wall thermostat to, say, 30 degrees, so that it never turns off the boiler when the hall is warm but other rooms are cold and their TRV wants heat. Is that right?

    If so, does that mean the boiler would be permanently sending heat round the system, even if none is required, so the pipes would be permanently hot, even if they are bypassing every radiator? That doesn't sound very efficient. Does that mean it is much more efficient for the smart system to control the boiler, so it only produces heat when a TRV is calling for it? If so, why is boiler control optional or even, in the case of Eve, not even an option? Am I misunderstanding something?

    For the avoidance of doubt, my query is not about hot water. We have a conventional boiler, feeding hot water to a tank, and this seems fine with the current timed controller. If the smart system controlled the boiler for hot water I think I would just reproduce the fixed timings, so I don't think there is much point in paying more for this.
    Last edited by IvanOpinion; 1st October 2021 at 01:08 PM.

  2. #2
    Automated Home Guru
    Join Date
    Sep 2018


    Fit boiler control, it will be inefficient otherwise, with the boiler cycling when TRVs are closed.

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