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Thread: Evohome woes

  1. #21
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    I confess that I don't really care what the TRVs are doing. Eighteen months or so on from installation, optimisation with the original controller does work as it usually wakes me up every morning. Earlier this week, with an OAT of M5C, the HR92s in my bedroom whirred at 0655am. Today, with the OAT about 10C higher, the HR92s whirred at about 0715am. All that said, it would be nice to have an icon on each zone display to show when a particular zone is asking for heat.

  2. #22
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    Quote Originally Posted by paulockenden View Post
    There MUST be something in the API that gives zone state, because SmartThings (which is a cloud to cloud integration) shows it.
    Nope Paul, SmartThings simply sees the requested temperature is lower then the actual temperature and concludes the unit/zone is requesting for heat from that info. I've looked into the data the API provides over and over and the 'heat' status always shows OFF. There is no way SmartThings can show something that simply isn't there. Just like MrB said, SmartThings is assuming the valve is open and/of the unit is requesting for heat and shows just that. That is not the same as the unit reporting what it is doing, and the API passing on that info.
    Last edited by Krejt; 21st February 2016 at 08:46 AM. Reason: forgot quote
    Evohomeclient temperatures on ThingSpeak: https://thingspeak.com/channels/79213

  3. #23
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    Quote Originally Posted by Krejt View Post
    Nope Paul, SmartThings simply sees the requested temperature is lower then the actual temperature and concludes the unit/zone is requesting for heat from that info. I've looked into the data the API provides over and over and the 'heat' status always shows OFF. There is no way SmartThings can show something that simply isn't there. Just like MrB said, SmartThings is assuming the valve is open and/of the unit is requesting for heat and shows just that. That is not the same as the unit reporting what it is doing, and the API passing on that info.
    Hi Krejt, I assume you're talking about the API that we all use for graphing? That is what I would call the "unofficial" API, as it was reverse-engineered from what is used by the phone app. But there is also an "official" API that you have to sign up for (I tried, and never heard back), so I wonder if the official API does provide that information?

  4. #24
    Automated Home Legend top brake's Avatar
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    sounds like a double bind issue, did you factory reset and delete the existing BDR91 binding before creating the new system?

    Quote Originally Posted by graham.gibson View Post
    I recently fitted Evohome to an S plan system – Worcester Bosch 30CDi conventional boiler, Grundfos Alpha2L pump, Honeywell 2 port zone valves and Honeywell ABV – all about 2 years old. HR92s on all rads. BRD91 as heating valve controller and second BDR91 as hot water valve controller. 12 out of 15 rads have Danfoss RA/VL TRVs with the HR92 adapters. Boiler temp is set to 60 degrees.

    On the one hand, things are mostly ok – hot water and internet control are perfect and the setpoints are largely maintained in each zone. Sometimes the temp in a zone falls well below setpoint and I have to reset the corresponding HR92 – I suspect this is a symptom of my Danfoss RA/VL valve bodies being old. I have managed to resolve quite a few niggles along the way (and many thanks to Richard from Evohome Shop who has been extremely helpful), but I have a further niggle and I thought I would reach out to the experts on this forum for advice.

    If I reduce the temp in all zones, the TRVs turn off, but the heating BDR91 remains on for some time before turning off. The BDR91 then comes on from time to time, presumably to keep the temp ‘topped up’ in the zones (or perhaps for some other reason). However, I've noticed in some cases that my heating return pipe remains cool and instead the hot water just circulates round the bypass loop. I don’t know if this is because the HR92s think that they are opening but the underlying RA/VL(s) are not actually opening, or if the HR92s are opening partially such that the flow in the heating circuit is very low and the bypass kicks in to maintain minimum flow rate, or if the BDR91 is firing incorrectly when there is no demand (or some combination of these). When the system is in this state, the boiler gets into a constant cycle of firing up, heating to 60 degrees, going off, water then rises to around 67 degrees as heat is only being dissipated via the bypass loop, cools down below 60 then the boiler fires up again then repeat.

    What’s troubling me is that when the system gets into this state, all that appears to be happening is that the bypass loop is being heated all night, which seems to be a waste of energy to me and also unnecessary repeated firing of the boiler.

    I’d welcome any advice on how to definitively troubleshoot this issue. I’m concerned that I’ll have to replace all of my RA/VLs (which is a complete pain as I’ll have to extend the pipework at each rad) or continually waste energy or return to a single zone configuration using a room stat and no TRVs in that room (which would be a waste of Evohome’s capabilities).

    Thanks,
    Graham
    I work for Resideo, posts are personal and my own views.

  5. #25
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    Hi,

    Thanks for all the comments - it's great to see such an active Evohome community.

    Yes, I did factory reset the BRD91s first.

    I did a bit of reconfiguration at the weekend and my system *seems* to be behaving itself a bit better now - time will tell if it's fully sorted. The key thing is that the temperature in all zones is tracking at or very close to set point at all times now, and a 24 hour time-lapse that I did of my boiler, pump and BRD91s did not show any alarming increases of boiler temperature that I was getting before. What I did included (which will hopefully be useful to others):

    • Replaced all of the gland seals in my Danfoss RA/VLs (new pins effectively) - an easy job that can be done without draining down
    • Re-seated all of the HR92s to be lightly tight just after hitting the pins
    • A full reset of all components and re-creation of all zones and binding, allowing time when binding for the HR92s to sync
    • Changed valve stroke to full on a couple of rads that were not heating up as much as they did without HR92s on them
    • Adjusted my pump and ABV settings to be properly in tandem
    • Uninsulated 3m of bypass loop as suggested by Richard of Evohome Shop


    A time lapse that I did last night showed that the heating BRD91 went off at 11pm when the temp in all zones dropped to 16 degrees (I've kept the default controller schedule for now until the system learns the rooms) and it stayed off for a couple of hours. It then came on from time to time, presumably to keep the zones topped up. So far, the temp in all zones has been pretty consistent - under or overshooting only by about half a degree.

    I'll need to keep an eye on things over the next few days, but my confidence has improved a bit. I suspect the issue I've seen (and maybe that others have seen) is that an HR92 is calling for 'top up' heat (i.e. low demand) but the underlying valve is not opening enough (or at all) so the BDR91 stays on and the water ends up being heated and cooled through the bypass loop in a constant cycle.

    Regards,
    Graham
    Last edited by graham.gibson; 22nd February 2016 at 11:20 PM.

  6. #26
    Automated Home Legend paulockenden's Avatar
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    Who on earth put insulation on your bypass loop? That shows a lack of understanding about what the loop is actually for.

  7. #27
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    A Worcester Bosch accredited installer.

    The random BDR91 firing is back. Setpoint of all zones is 16 degrees. Actual temp of all zones is >=20 degrees. BDR91 is still cycling on and off. Seems crazy to be calling for heat when all zones 4 degrees above setpoint. All this is doing is heating the bypass loop - a waste of energy and unnecessary cycling of the boiler.

  8. #28
    Automated Home Legend paulockenden's Avatar
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    Something is wrong. Your zones are well above the TPI band.

  9. #29
    Automated Home Legend paulockenden's Avatar
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    It's going to sound bonkers, but I'd suggest manually going round the house and removing the HR92s (or just flicking the in lip switch) on them, until you identify the culprit.

    Rather than doing them sequentially, a binary chop might be quicker. Do half, then half of those, etc.

    Just remember that the effect won't be instant - you might need to wait 20-30 mins to see whether the random firing stops.

    Hopefully you'll narrow it down to one HR92 calling for heat when it shouldn't.

  10. #30

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    Did this get sorted?

    (Been away so replying late) but what you originally stated pointed to a double bind.
    getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own

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