Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 35

Thread: Boiler Pump/Fan cycling at random? Evohome at fault?

  1. #11
    Automated Home Guru
    Join Date
    Oct 2016
    Location
    Bath, UK
    Posts
    151

    Default

    No cycling tonight, I think it's now stable and tomorrow I will turn off Optimum Stop and then if the cycling does not return I have a near default system and it has stabilised as Honeywell said it would after about 2-days.

  2. #12
    Automated Home Guru
    Join Date
    Oct 2016
    Location
    Bath, UK
    Posts
    151

    Default

    No the cycling has returned because I switched off Optimum Stop. I checked the schedule versus the room and HR92 displayed temperatures and the minimum temperature difference was 4'C maximum 6'C at 23:00 when all zones go to 15'C.

    The BDR91 continued to demand heat with no load/radiator/HR92 demanding heat, actually tonight is relatively mild here and the heating was not running at ~22:30.

    I observed this behaviour for 2 random cycles then switched the Optimum Stop back on and it's stopped.

    I'm running the 1.03 Firmware...and I now think there's a problem with this version.
    Last edited by g6ejd; 28th October 2016 at 12:24 AM.

  3. #13
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    1,845

    Default

    Hmm.

    So when the boiler was still cycling you went around the house and manually checked the set point on each HR92 ?

    If they were all set 4 degrees or more below current measured temperatures there should definitely be no demand.

    I still can't see how it could be related to optimum stop because all optimum stop does is send the lower set point to the HR92's sooner than the scheduled time. There is no other "magic" involved and it has no impact on how HR92's send their heat demands...

    Could be a bug I suppose. Have you tried a controller reboot ? Soon after switching to an S-Plan configuration with three relays I too noticed the boiler relay cycling on and off with no demand from HR92's (yes I ran around the house and checked - they were all set to 5 degrees) and it kept doing this until I did a reboot of the controller.

    After that it was OK, so I'm going to suspect a bug in the firmware that perhaps causes it to get confused after BDR91 bindings are changed or reconfigured. Try turning Optimal Stop back off, give it a couple of minutes then reboot the controller - see if that helps.

    There is some anecdotal evidence that certain types of system reconfiguration must be followed up by a controller reboot to ensure everything works correctly. In fact recommended advice from the evohomeshop when rebinding devices especially BDR's is to remove all the bindings first, reboot the controller then re-add them!
    Last edited by DBMandrake; 28th October 2016 at 12:56 AM.

  4. #14
    Automated Home Legend paulockenden's Avatar
    Join Date
    Apr 2015
    Location
    South Coast
    Posts
    1,602

    Default

    It could also just be system delays.

    At the set point the hr92 will change its demand on the boiler. But this is sent upstream to the controller first which aggregates the demand from the various actuators in the system, and that can take a few minutes as they all drop off.

    I wonder whether that's what you are seeing?

  5. #15
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    1,845

    Default

    In my experience the only big delay in shutting down the system is the up to 4 minute delay in the controller sending a set point change to all the HR92's.

    Changes in heat demand from HR92's are sent almost immediately and forwarded on by the controller almost immediately as well.

    Typically it takes only about 3 seconds for a heat demand to be forwarded all the way through to the boiler relay, although the HR92 will not send the new heat demand until it has finished rotating its valve - so if the valve is turning from one extreme position to the other instead of an incremental movement there can be an extra delay of about 30 seconds while the valve turns before the new demand is sent. So 4 minutes 30 seconds is the longest it should ever take for the boiler to shut down after a heating off quick action or scheduled drop in all rooms.

    When testing response time keep in mind TPI can cause an apparent delay in response for changes between partial heat demands of up to 10 minutes depending on where you are in the current TPI cycle. So if you just turn a room up by 1 degree it will still be a partial demand which means the relay may not react immediately to the different heat demand.

    However if you go from zero demand to full demand or vica versa there is no TPI induced delay and you will observe that the response time is about 3 seconds after the HR92 finishes turning its valve.

  6. #16
    Automated Home Guru
    Join Date
    Oct 2016
    Location
    Bath, UK
    Posts
    151

    Default

    I have deliberately waited for 2 (random) cycles to complete before I intervene, these occur over an approximate 20-min period. The system worked normally and follows the schedule exactly during the day and I did walk around all 14 HR92's to check their display read what the controllers was saying, in cases 15C as per the schedule, the house was warm throughout and last night the outside temperature here was 12.6C and I know from experience that differential (15-12.6) will not create a heating demand, for this property it needs to be more like 6-8C to do that.

    What I can't reconcile is why a heating demand should continue beyond the schedule end-time and left unchecked keep doing that.

    I'm still puzzled when I did the full system reset that I took the Controller off the wall-mount, did the system reset, then removed the batteries and was stood in-front of the BDR just about to reset them, well clear the bindings, when to my surprise the heating BDR came on. It could not have been the Controller, so there has to be some autonomy between HR92's and the BDR or the BDR just keeps switching on and following its last known command.

    Thinking there are RF problems (range) yesterday I did a range check and get 5-bars/maximum signal for each HR and the CS92 and BDR's. The Controller to BDR and CS92 range is about 2M, the Controller to furthest HR (line-of-sight) is 5M.

    I'm using Optimum Stop as a method to stop the cycling which was derived randomly, but I have found the Eco Quick action or Away does the same, albeit I have to switch those modes off for the following morning's schedule to resume.

    My neighbour has a Evohome and I recall him saying he has a similar problem, that's before I purchased my system, but now I think I realise what he was referring to, he told me he had set-up his many zones to just two in a bid to isolate the problem, hopefully I'll see him today and can ask him as this is more than a coincidence and his system is about 3-months old, so it's likely his system is the latest firmware too.

    For now I know that switching on Optimum Stop prevents this unwanted operation, but today I think I will call Honeywell again and report a problem rather than discuss things to try.

  7. #17
    Automated Home Legend paulockenden's Avatar
    Join Date
    Apr 2015
    Location
    South Coast
    Posts
    1,602

    Default

    Quote Originally Posted by g6ejd View Post
    so there has to be some autonomy between HR92's and the BDR
    Nope.
    Quote Originally Posted by g6ejd View Post
    or the BDR just keeps switching on and following its last known command.
    I believe that's how it works. The controller doesn't manage every on and off, it sends a "keep switching on and off at this rate" to the BDR.

    P.

  8. #18
    Automated Home Guru
    Join Date
    Oct 2016
    Location
    Bath, UK
    Posts
    151

    Default

    OK, thanks for that confirmation, so in my case and assuming the Controller sends an Off command when the schedule ends, it looks like that command is never received, except if I send the same via Eco or Away it is or Optimum Stop it sends a defined off and that is received and heating stops near instantly.

    I'm still thinking this is a BDR fault, but it works normally all day long or most likely firmware issue.

    It would be neat if RAMESES could look at my system to see what's going on if Honeywell can see more detail than I can surmise.

  9. #19
    Automated Home Legend paulockenden's Avatar
    Join Date
    Apr 2015
    Location
    South Coast
    Posts
    1,602

    Default

    Quote Originally Posted by DBMandrake View Post
    Changes in heat demand from HR92's are sent almost immediately and forwarded on by the controller almost immediately as well.
    But the demand value passed to the BDR isn't just from a single HR92 is it. The controller aggregates the demand from a number of different HR92s (and possibly other devices). Averaging them out to a single value.

    I suspect it might be THIS process which can be laggy at times.

    When I first had Evohome I'd obsess about the boiler firing for a few seconds when it shouldn't. But these days I'm more "so what?". My house is comfortable and controllable. That's really all that matters. I've learnt to ignore the quirks.

    P.

  10. #20
    Automated Home Legend
    Join Date
    Sep 2014
    Location
    Scotland
    Posts
    1,845

    Default

    Quote Originally Posted by paulockenden View Post
    But the demand value passed to the BDR isn't just from a single HR92 is it. The controller aggregates the demand from a number of different HR92s (and possibly other devices). Averaging them out to a single value.

    I suspect it might be THIS process which can be laggy at times.
    I've done quite a bit of testing of the behaviour of heat demand changes in the past trying to figure the system out and I have not seen any evidence of significant processing or transmission delays here.

    HR92's don't send an updated heat demand until they have finished adjusting their valve position, which depending on how far they have to turn can add a delay as the motor turns, but other than that a new aggregate heat demand is forwarded on to the BDR91's from the controller in mere seconds, and it seems very reliable and consistent.
    When I first had Evohome I'd obsess about the boiler firing for a few seconds when it shouldn't. But these days I'm more "so what?". My house is comfortable and controllable. That's really all that matters. I've learnt to ignore the quirks.
    I know what you mean - the nature of the wireless communications and infrequent wireless transmissions can lead to some behaviour that looks quirky at first glance but which is actually easy explained once you understand the system.

    The classic example is "I've turned the heating off but 3 minutes later the boiler relay just came on again". Perfectly normal behaviour when you understand that it can take up to 4 1/2 minutes for set points to be sent to and acted upon by HR92's, and that in the meantime the BDR91's will to continue to follow their existing heat demand TPI schedule, which by chance might bring the relay back on for a bit after you turned the heating "off". But a few minutes later it should go off again and stay off.

    But I have definitely seen times like g6ejd where even my understanding of how the system works cannot explain why the boiler relay is continuing to cycle on and off when all HR92's are set to 5 degrees and have been for at least 20 minutes. I had this happen to me when I converted from heating only with one BDR91 to S-Plan with 3x BDR91, and during that process various combinations of removing/clearing bindings and reconfiguring / making new bindings was performed, and to the best of my knowledge, correctly.

    But for some reason the relays kept cycling when there was no demand until a controller reboot, and things are OK now. So I think there are a few bugs/quirks in the software that can be hit when major configuration changes are made to the system like moving from no hot water to hot water control.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •