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Thread: Tracking down random boiler demand with Evohome

  1. #1
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    Default Tracking down random boiler demand with Evohome

    My evohome is controlling a combi - so no hot water via evohome.

    I've gone to bed (it's been a very long day) so currently only one (of 12 zones) active. Rest set to 5deg. No local overrides set.

    Optimised start/stop is active (max 1 hour). No programmed set points until tomorrow so shouldn't be any optimised startups in progress.

    Set point on active zone is 22 degrees c. Current temp on this zone is 23degrees so no demand for heat.......so why can I hear my boiler starting up every 10 minutes or so ??? running for 10 minutes and switching off. (Rinse/repeat) Been happening for the last hour or so.

    Evohome is demanding heat as the bdr91 light comes on (I've been out of bed to check). Controller and rad control both show 'over' the set point.


    Why the boiler demand ?

    Don't feel like I'm saving my 45% on heating bills at the moment

  2. #2

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    Temperature is never static - its either rising or falling.

    In the case above - the boiler is being 'throttled' to maintain your 22 degrees. Just because its 1 degree above what you want - doesn't mean that evohome wont predict the heat loss curve of the room. Eg if it waited until 22 degrees, then by the time the boiler had fired and the rads had filled, and then effect had started to take place - then the room could be at 19 degrees, at which point your comfort is compromised and the boiler has to play catchup.

    PS If you absolute control (by this I mean only a call for heat when a specific value is achieved) - then turn optimisation off.
    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

  3. #3
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    I partially agree - but in the last hour the boiler has fired on and off about 6 times. The temp has never dropped below 1 degree ABOVE the set point.

    I can understand evohome doing this once.....but every 5 to 10 minutes - 3 more times since that last post. That doesn't seem smart at all ? That seems to assume the heat loss curve was nearly vertically downwards ie it needs to top up every 10 minutes to 1 degree above the set point.

    It's not a new install so it should know the correct curve ?

    I have what I thought was a max boiler cycling option set in the controller too (think its 6 per hour?)

  4. #4
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    Quote Originally Posted by orange View Post
    Why the boiler demand ?

    Don't feel like I'm saving my 45% on heating bills at the moment
    This could well be the fact you have bound your system incorrectly or double bound an item. I've seen this happen a few times with my customers and all have been because they have bound something incorrectly or rushed the binding process, especially using guided config. Once I have walked them through a complete rebinding process this has been eliminated.

    I would suggest a rebind of the system, be sure to unbind everything completely and rebind everything maliciously.

    I only normally technically help my own customers, but seems you have had some issues so maybe give me a call and I will help - 07884 110955.

    Thanks,

    Richard

  5. #5
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    thanks Richard - I gave up and switched the heating off in the end

    I'll try rebinding - but it's odd as that's been working fine for the last few months. I'm fairly convinced it's not double bound and temps report back fine to the controller and the controller seems to talk to the valve ok plus local override works ? Easy enough to rebind.

    Thanks also for the offer of support (I did get the system from you originally) It's not really a show stopper but I think it's important that honeywell add some kind of logging to their system - then it would be easy to spot what was going on in this instance.

  6. #6
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    My only thoughts are as The Evohome Shop suggests, try re-doing the whole lot. It means a factory reset of all, power off and batteries out for a bit for the Controller. A pain but it could well clear the issue. For other reasons I did an electronic reinstall of everything last weekend. I had issues with the hot water in that it was not coming on when it should nor going off. It seemed to trigger when I did not want it. The answer was something had happened in the binding process that I think left the heating relay bound before the hot water one. Having learned so much from these pages (and yes most ought to be in the manual) I just took my time going through each step carefully ensuring it all was setting up as it showed.

    After ensuring all was reset and nothing anywhere was bound the sequence was bind water sensor to controller, bind hot water relay to the controller, bind heating relay to the controller, ensure optimisation, choose number of zones and then one by one slowly ensuring each TRV was bound after first ensuring each was the temperature sensor and not the controller. Fished off with binding the Gateway. All works and as it works for most readers it just could be a binding has not occurred as it should.

    Remember to wait a few minutes after doing the binding and not to rush off to do the next one as this gives the system that moment to build up its memory. The syncing of each TRV only took a few minutes.

    It all does work well. Indeed I came in the back door this morning, looked at the control panel which is next to the boiler and noticed the hall TRV was showing there was an open window. No windows in the hall so assumed a parcel must have been delivered and my wife had open and shut the front door! Almost like big brother!

    My only issue now is using the app on my iPhone when roaming but I think I may have an inkling now of what the problem is - mine, not Honeywell's!

    Always remember that a lot of problems are caused by user error, i.e we create them with playing around! But then if we did not play around with these things we would not come across actual issues nor ideas for the future! Helpful though to have a proper manual.

  7. #7
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    Quote Originally Posted by orange View Post
    thanks Richard - I gave up and switched the heating off in the end

    I'll try rebinding - but it's odd as that's been working fine for the last few months. I'm fairly convinced it's not double bound and temps report back fine to the controller and the controller seems to talk to the valve ok plus local override works ? Easy enough to rebind.

    Thanks also for the offer of support (I did get the system from you originally) It's not really a show stopper but I think it's important that honeywell add some kind of logging to their system - then it would be easy to spot what was going on in this instance.
    If you bought the system from us, then deffo give me a call. I really do support every sale, so please don't think you cannot call me! One thing I pride myself on is helping my customers who have invested in a system we have supplied.

  8. #8
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    Quote Originally Posted by G4RHL View Post
    My only thoughts are as The Evohome Shop suggests, try re-doing the whole lot. It means a factory reset of all, power off and batteries out for a bit for the Controller. A pain but it could well clear the issue. For other reasons I did an electronic reinstall of everything last weekend. I had issues with the hot water in that it was not coming on when it should nor going off. It seemed to trigger when I did not want it. The answer was something had happened in the binding process that I think left the heating relay bound before the hot water one. Having learned so much from these pages (and yes most ought to be in the manual) I just took my time going through each step carefully ensuring it all was setting up as it showed.
    the only problem I have is that the 'start over again' approach may or may not fix it. What Honeywell need to do when they have problems is to find the cause of them so they can fix it for everyone.

    For example - the issues you've been having were (partially) fixed by a deleting your account and starting again (essentially) - that's not a fix as far as I'm concerned. Obviously as an end user you might not care as you're just happy to have it working. That doesn't mean that the same issue isn't going to bite you again or other users. It seems the support guys have no real access to the developers so all they are left with no alternative than just turn it off and on again

  9. #9
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    Well what I find is most people rush the binding process and as they do not do multiple systems like I do, don't realise when the binding has gone wrong. By talking over the phone with me, I can reassure you are binding the system correctly and at least then if there are still issues, you have eliminated binding from the equation.

  10. #10
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    hi Richard - thanks again for the kind offer - how do you know if the binding has gone wrong ? Any symptoms apart from general weirdness ?

    only one sensor/valve per zone and all working fine - reporting temps and controlling fine - radio strength ok - local override works as expected - no logged errors - optimum start working fine on all zones etc. Happy to rebind (and will) but not sure what we should be looking out for as a fault to guide us ?

    My suspicion is that it's calculated the heat loss curve for the room either incorrectly or strangely. Basically it's scared to let it drop down to the set point as it's not sure it can bring the temperature up quickly enough (essentially what Ramases is saying) - In this instance it would seem to me that the system should arrange a larger hysteresis loop for the temperate rather than quickly cycling the boiler every few minutes.....

    what I'm I think I'm saying is I think this is a 'feature' not a fault.

    decent logging would of course let us know

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