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Thread: Heating Control with limited intelligence

  1. #1
    Automated Home Jr Member NWootton's Avatar
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    Question Heating Control with limited intelligence

    Prices going up, bills getting bigger, so I'm looking to add a little intelligence to the heating system in the house.

    We currently have manual TRVs and the heating & hot water timer is still the traditional 5/2 type. I'd like (as a short term solution) to replace the TRVs with controllable ones (probably Z-Wave - Danfoss or StellaZ) and then use the home controller to alter the desired temperature (set point?) at various times during the day. This way I direct the heating into the rooms that are occupied and not into empty ones when the boiler fires. I'm NOT looking to change the timer at this point!

    For example set the bedroom to be 21 oC between 06:00 and 07:00, drop it back to 18 oC between 07:00 and 18:00 and then raise it to 21 oC between 18:00 and 22:00 and then drop it back to 15oC between 22:00 and 06:00. Other rooms would have their own cycles based on current usage.

    My question is this - is this feasible and would it work? I know I can make it more efficient by porting the entire heating system over to Z-Wave or EvoHome in its entirety, but the finance committee is not convinced, so small steps. I know that depending on the TRV used, I may need to add room thermostats to record actual temperature before we go fully automated, but will we need them in the scenario described above?

    Thoughts?

  2. #2
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    So the finance committee is willing to spring for best part of 50 a radiator plus a couple of hundred quid for a controller but not for the extra 64 that would mean some real savings...

    In theory it should work fine and will help balance out the rooms and should speed up heating up times for the rooms that are used. The difficulty seems to be that the wireless thermostats only wake up intermittently so if you have a lot of them waking up round the same time there can be issues with the controller finishing communicating with them before they go back to sleep. Certainly thats the case with indigo (though I'm informed a fix to improve things is on the way), I'm less certain about the situation for the dedicated systems; but my trawls looking for info on the Stella-Z didn't throw up any confirmation of working whole house systems (whereas autolog who posts on the indigo forums seems to have a working system, albeit with some teething troubles he's sorting out with the devs).

    I'd definitely go for Stella-Zs over the Danfoss option as they seem to work better and do report temperature so you don't necessarily need a room thermostat.

  3. #3
    Automated Home Jr Member NWootton's Avatar
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    Thanks wysinawyg, I never said the finance committee was sensible, just not yet convinced!

    I already have the controller, so the outlay for the system is basically for the StellaZ or Danfoss TRVs. By my money that's 500 for 10 units vs. the ~2k for an EvoHome system.

    I'd still rather have the EvoHome, if only because I'm more likely to 'experiment' with my own build and break something critical (hell hath no fury like a cold wife and kids!), but coughing up an extra 1500 is hard to justify.

    I may just start even smaller and put StellaZ on the bedroom radiators. Limiting their output will be a reasonable start and may show me the flaws.

    Worse case, it all goes south, I eBay the StellaZ and use it as justification for EvoHome!

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  5. #5
    Automated Home Jr Member NWootton's Avatar
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    Dammit! Time to prepare a new pitch to the finance committee... Maybe I can persuade her the new one is worth the cash!

  6. #6
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    I'm also looking for a solution similar to this.
    Basically I'd like a heating system that can operate TVRs to have different temperatures in different rooms. It just makes sense to me.
    The new Evohome system seems to be a good start. It'd be fantastic if we could have that and merge some of the features of Tado (http://www.tado.com/gb/this-is-tado) to sense if you're in or not.

  7. #7
    Automated Home Jr Member NWootton's Avatar
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    biccies

    I agree. And the new EVoHome with the ability to do 12 zones and all the new shiny stuff makes it the best choice. Finance committee is coming around.... maybe by the time it's released!

  8. #8
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    I will also need to convince the finance committee. I'll be keeping my eye on the EvoHome and I've added my email to their "notify" section. I just find it mad that these systems are not more commonplace, especially with the high price of heating!!

  9. #9
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    In addition to all the technology (which does in principle what you want, but at a price, as your Finance Committee has pointed out) why not consider a Weather Compensator?

    A WxC reduces the flow temp as the outside temp increases. thus making the condensing boiler (assuming you have one, if not, start there) [much] more efficient. Claims of 12-15% are made. This is likely, though I don't have data yet, as its principal job is to turn off the boiler when it would otherwise be on unnecessarily. You can buy them, though I made one. Mine reduces the flow temp by 2C for every 1C above 0C outside, and cuts heating off completely at 15C (adjustable). It is wired in as a room stat, with temp sensors on the flow and return pipes and outside.

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