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Thread: Evohome - Lost comms with pretty much everything?

  1. #21
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    Ok, bit of an update. I have factory reset the evohome again and this time completely ignored the DHW system, instead just binding the boiler relay and rooms. So far (touch wood) it is working ok, leading me to believe it is indeed a problem with the DHW relay.

    The weird thing is, I havenít bound anything from the DHW side of things, but somehow evohome is still reporting DHW temperature? How! lol

  2. #22
    Automated Home Ninja Dan_Robinson's Avatar
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    Depending on how long you left it after the reset before tinkering again.... I'm not convinced that the factory reset always erases everything.... Especially on the v2's.

  3. #23
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    Quote Originally Posted by garmcqui View Post
    Ok, bit of an update. I have factory reset the evohome again and this time completely ignored the DHW system, instead just binding the boiler relay and rooms. So far (touch wood) it is working ok, leading me to believe it is indeed a problem with the DHW relay.
    A little clarification needed here - you have two BDR91's, not three, correct ? And the zone valves fire the boiler ?

    If so, you are aware that you should not bind a Boiler relay in a two relay stored hot water configuration ? Now granted, if for testing purposes you are deliberately leaving out the hot water system it would be correct to bind a boiler control relay as you are simulating a system with no hot water control.

    However when you bind the system correctly you bind the two relays within the stored hot water configuration section, and you must not attempt to bind a boiler control relay unless you do actually have a third BDR91 as a boiler control relay - as I do. You should leave it set to None. If you attempt to bind the boiler control relay when you only have two relays you will have a double binding issue with one of the BDR91's and the system will not work properly. You will also probably see comms errors reported.
    The weird thing is, I haven’t bound anything from the DHW side of things, but somehow evohome is still reporting DHW temperature? How! lol
    As Dan says it sounds like the factory reset isn't actually clearing everything. I've had that problem myself before.

    I think the generally recommended approach is to use the factory reset, go back to the home screen and wait a couple of minutes, (for the configuration to be written to non volatile memory) then remove the batteries while it is off the dock to trigger a reboot. It seems like even though configuration files get written correctly to non volatile storage, (flash) sometimes some of the configuration stays in ram until rebooted and can interfere with setting the system up again if you don't reboot in between the factory reset and reconfiguration.
    Last edited by DBMandrake; 22nd September 2017 at 10:35 AM.

  4. #24
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    Does any of the above help to explain what might have occurred in the the original post? I don't see how a failed BDR on the HW side of things would impact on the CH - or have I misunderstood what was reported?

    Quote: The controller had lost comms with all 4 zones as well as the DHW sensor and a comms test to both the DHW relay and the heating demand relay failed. Unquote

  5. #25

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    Quote Originally Posted by Dan_Robinson View Post
    Depending on how long you left it after the reset before tinkering again.... I'm not convinced that the factory reset always erases everything.... Especially on the v2's.
    The factory reset does reset everything on the evo - however there will be 'calls' from the legacy devices looking for the previous evo - unless you reset those components (HR92, BDR91 etc) - evohome will try to make sense - chuck and error - but it wont stop you binding. However as the BDR91 for example can be dual bound - you will get 'calls' which will appear as errors.

    Best practice is if you need to hard reset the evo then ensure other components are equally wiped.
    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

  6. #26

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    Quote Originally Posted by DBMandrake View Post
    A little clarification needed here - you have two BDR91's, not three, correct ? And the zone valves fire the boiler ?

    If so, you are aware that you should not bind a Boiler relay in a two relay stored hot water configuration ? Now granted, if for testing purposes you are deliberately leaving out the hot water system it would be correct to bind a boiler control relay as you are simulating a system with no hot water control.

    However when you bind the system correctly you bind the two relays within the stored hot water configuration section, and you must not attempt to bind a boiler control relay unless you do actually have a third BDR91 as a boiler control relay - as I do. You should leave it set to None. If you attempt to bind the boiler control relay when you only have two relays you will have a double binding issue with one of the BDR91's and the system will not work properly. You will also probably see comms errors reported.

    As Dan says it sounds like the factory reset isn't actually clearing everything. I've had that problem myself before.

    I think the generally recommended approach is to use the factory reset, go back to the home screen and wait a couple of minutes, (for the configuration to be written to non volatile memory) then remove the batteries while it is off the dock to trigger a reboot. It seems like even though configuration files get written correctly to non volatile storage, (flash) sometimes some of the configuration stays in ram until rebooted and can interfere with setting the system up again if you don't reboot in between the factory reset and reconfiguration.
    As per DBMandrake says - this is a common issue - people bind a boiler relay - when they don't have one. They just need to bind the valves - who in-turn will fire the boiler (usually via a hard wire connection to boiler)
    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

  7. #27
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    Ok, apologies for leaving it so long to post.

    I am pleased to say a replacement BDR91 DHW relay seems to have solved the problem. All zones are now working properly, and the DHW responds to demands as it should.

    Now, as for the configuration.... My parents' system is a slightly unconventional configuration in that the unvented DHW cylinder was added quite some time after the CH was installed (before this they only had DHW heated by immersion). Their oil-fired boiler is in a garage some 60ft from the house, and so (to avoid having to dig up and re-lay the driveway) the DHW cylinder was simply plumbed into the CH circuit. Think of it as just another radiator, isolated by a 2-port zone valve.

    The way I configured it initially was as an S-plan system, where a CH relay and a DHW relay were bound to the evohome and controlled a CH and DHW zone valve, with boiler then being activated by the zone valve end points. However it quickly became apparent that this wasn't going to work, as if there was DHW demand and no CH demand, the CH zone valve remained closed and so the boiler simply pumped water around the bypass.

    So, the way it is currently configured is with a DHW relay and a boiler demand relay. The 'CH Zone Valve' is simply locked open. If CH is called for, the boiler relay activates the boiler/pump and all is well. If DHW is called for, the DHW relay opens the DHW zone valve and the boiler relay activates the boiler/pump. If no radiators are calling for heat, just the DHW is heated. It has been working perfectly this way for almost a year now.

    This was the main reason I put the Evohome system in for them, as prior to this they could have Central Heating without DHW, but there was no way for them to have DHW on without Central Heating (unless they manually went round and turned the TRVs off), which was just daft.

    I hope that makes sense.

    G
    Last edited by garmcqui; 26th September 2017 at 12:58 PM.

  8. #28
    Automated Home Guru MichaelD's Avatar
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    Quote Originally Posted by garmcqui View Post
    .... Their oil-fired boiler is in a garage some 60ft from the house ....

    G
    Wow, they must lose a huge amount of heat travelling 60 ft to the house then another 60ft or the return. But, I guess they appreciate a heated drive on those icy mornings

  9. #29
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    it's ridiculous but it has to be that way apparently (what's even more ridiculous is that the boiler isn't even a condensing one!). I remember the pipework being put in when I was a teenager. I believe they are pre-insulated 32mm supply/return pipes, but the diameter of the insulation was well over 200mm.

  10. #30
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    Quote Originally Posted by garmcqui View Post
    Ok, apologies for leaving it so long to post.

    I am pleased to say a replacement BDR91 DHW relay seems to have solved the problem. All zones are now working properly, and the DHW responds to demands as it should.
    Interesting - a completely dead DHW BDR91 should not interfere with the functioning of the rest of the system, only the hot water should have failed....

    However it is possible at least in theory for it to develop a fault where it starts spamming the radio channel with RF interference or junk transmissions - which would then interfere with all comms between all Evohome devices since they all work on the same shared access channel.

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