• Hello there.
    So what I am trying to project is a differential temperature control in the rooms of the house.
    The idea is that each temperature sensor in one single room commands via HA open/closed a valve of the radiator. The idea would be to 3d print an assembly at the existing valve with a DC motor that could turn clockwise / counterclockwise for an amount of time (let's say 10 seconds) so to open/close the valve. Do you think this is a reasonable idea? Is there a way to make motor spin either way depending on the message that arduino receives? I know you can buy smart valves off the shelf but they are expensive plus this is a more challenging/creative option.
    I will stop for now hope it's clear. Cheers

  • @topgun78 2 things to consider...

    1. printing in PLA may not be a good idea for this as heating pipes can get to <70C and will softern the material and make it more brittle.

    2. Use a stepper motor so that you can control it in microsteps to get 0-100% as sometimes it needs to be on at a lower level all the time. If just using open/closed you will get cycles of hot and colder room, not ideal.

  • @topgun78 Controlling a motor is easy enough, but what you are considering making will almost certainly bring you a world of pain and probably exceed the cost of a commercial version off the shelf.
    Plenty have hacked into the control side of it with active forums in Holland and Germany if that interests.
    If the real challenge is to improve heating, perhaps you might reconsider approach for a more physical one ?

    From my own experience, upgrading the insulation yourself brings the single greatest and most cost-effective benefit, the other is fitting decent thermostatic valves and heads.
    Here in 2017 the house got additional insulation, original heads and valves changed over to Heimeier Eclipse, one radiator and towel-rail uprated and it all paid for itself from the first year's gas savings which halved my gas bill.

    From +/-1.5 in 2016 to +/-0.5c in 2018 in every room at -20 outside, running 24/7 and not a battery in sight (except for the monitoring system UPS).
    Once you get a heating system balanced and set up, it simply works.

  • Thanks for your replies:
    @skywatch: yes I considered it infact I would leave some space for insulating material between the radiator and the installation. Also printing in ABS is a solution if warping issue is managed properly.

    zboblamont: thanks for your advices. Nevertheless this system would be on top of all the insulation works and the increase of overall efficency level. The fact is purely that you don't want a big house to be always fully warmed, but you want a schedule to change temperature throughout day/night according to your presence in the house. Thermostatic valves have the downside of setting the temperature at the radiator head but not being able to be changed from remote. Unless there are valves that can do that with H.A. but so far I am not aware of any with this feature...

  • @topgun78 I had a notion to zone control as I viewed it much the same as you have outlined, why heat the house when you're out for the day, but was surprised when I experimented to verify it.

    Gas and temperatures were monitored on Domoticz, but we do get pretty harsh winters here, ymmv. All the rooms had their own thermovalve settings.
    Most expensive to cheapest energy users were:
    Turn off rads in unused rooms.
    Turn down heating overnight.
    Turn down heating when out.
    Heating all the house 24/7.

    It sounds counter-intuitive until you consider every house has an over-rated boiler, and a combi boiler's efficiency tails off as the return temperature increases.
    There is a minimum heat you must dump before the boiler protects itself by shutting down. ie- how few rads must be available to sink the heat.

    I made a portable node with two clip-on DS18B20s to ensure all my rads return high temperature almost simultaneously to the boiler (ie balanced) over numerous heat cycles, so the majority of the heating is at max efficiency.

    I fully understand what you are trying to do and why, all I'm suggesting is decent rad valves and a fully balanced system will save you much more. 😉

    Good luck anyways..

  • I remember that here (UK) they recommend that to balance a radiator you need to aim for 12C difference between flow and return pipes on the radiator. A couple od DS18B20s should do the trick. I have monitored flow and return to the gas boiler for many years now in this way.

  • @skywatch My apologies for derailing the topic, yep, got two of the boiler feed and return also, and tapped into the trigger wire to notify boiler ON/OFF so Domoticz tracks the run time per day.
    12 degrees is recommended across the radiator but it's not quite so simple, it also matters WHEN you get that differential -
    That's where the portable node came in. Plastic pipe clips held sensors on the inlet and outlet pipes of the rad, the downstairs 6 all had a 11-12c differential at around 16/17 minutes, but no way would the upstairs 3 get there before the boiler cycle ended (room thermostat), which I put down to longer pipe runs.

    I increase the rate on the thermo-valve (pressure agnostic) to get the same heat on the return at ca 18 minutes. Rinse/repeat the remaining 2, eh voila. Balanced, a nice little peak on the return flow temperature at the boiler, reduced gas bills and every room +/- 0.5 of it's set point.

    Actual differential of these 3 upstairs radiators will be WAY under 12 for a constant feed, but for a heat cycle of 19-25 minutes depending on outside temperature it's perfectly balanced before the cycle ends.

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