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Thread: Why is the setpoint way over the set temperature?

  1. #21
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    Yes no load scaling on OT because OT is meant to already be an adaptive device. However the implementation is far from adaptive and made considerably worse if your boiler just blindly follows what the OTB tells it. Imagine if the boiler is ramping up to 90C, just because your small side room is less than 1.5C below the set point. It's madness.

  2. #22
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    Quote Originally Posted by bruce_miranda View Post
    Imagine if the boiler is ramping up to 90C, just because your small side room is less than 1.5C below the set point. It's madness.
    Exactly what I saw earlier. So no OT for me until that is fixed.

    Ah well, I think on/off works just as well, taking into account the boiler then also modulates its heat output to the set (55C) temperature. I do not know about the gas use but at least the electricity use is much lower, as one big difference I also noticed was that, under OT, the boiler pump was hardly switched off at all. More or less during the entire day it ran, albeit slow, most of the time pumping 20-25C water around. Now with on off the boiler heats and pumps water around until the heat request disappears, then pumps for another couple of minutes and then switches off.

  3. #23
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    Quote Originally Posted by Woody View Post
    Set it to partial and yes, the boiler heat demand increased immediately. Looks like it now translates the heat request of the office (84%) 1:1 to the boiler again.
    From what I've seen, zones that struggle to heat up can end up with their heat demand not scaled down nearly as much as zones which easily heat up or tend to overshoot - I think that's part of the heuristics as the load scaling ratio is different for every zone and changes gradually over time. (days) A couple of my zones don't scale down much and others scale down a lot.
    About OT and load scaling, does that mean that OT is supposed to do the load scaling always? My experience is different as, when I had the 8810 controlling the boiler, it overheated every now and the due to a large heat request for only a small room. Haven't seen that since installing the BDR and load scaling. Kinda silly if I could only prevent that by installing an on/off relay IMO.
    No load scaling for OpenTherm unfortunately and from the discussion with the Honeywell guys in the Beta thread this is on purpose and they don't believe that there would be any advantage to load scaling on OpenTherm.

    Some of what load scaling is trying to do is peculiar to TPI control but there are elements of it which I think would benefit OpenTherm.

  4. #24
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    FWIW my experience is as DB describes. My load scaling has been set at "normal" for some time and it's noticeable how much smoother things feel and how much less boiler activity there seems to be. All anecdotal of course but maybe 'perception of comfort' is key to the overall experience. My place is old, not super insulated (or otherwise) and fairly large but Evo is working yet better with the beta firmware.

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