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Thread: Confused on Boiler Relay AND Hot Water CS92

  1. #1
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    Default Confused on Boiler Relay AND Hot Water CS92

    Hello

    I have had Evohome for over a year and it has been working flawlessy...until I tried to add the hot water kit tonight?
    No matter what I seemed to select the Bolier relay BDR91 and the seperate hot water BDR91 seemed to merge when testing the RF?

    Background...
    I had originally an S+ system with a zone valve for upstairs and a zone valve for downstairs and a valve for the heating.

    I converted it to a valve for the hot water with a Honeywell timer type controller - disconnected the wiring to the heating valves and wired them open.
    I then have a BDR91 operating as a boiler relay.

    I searched for an hour trying to locate a wiring diagram for what I need but at a loss - any pointers?
    I need to keep the motorised valve for the water of course - so I cant see the option I need. Boiler Relay and single 2port valve?


    [I did at one time have a BDR91 connected to the heating zone valves but that seemed to break the BDR91 so I converted to a boiler relay setup]

    I am happy to adjust the pipework if I need to but please do remember I have 2 pipes - 2 zone valves for the heating, they are next to each other; if I had to introduce one valve for heating [feeding the 2 pipe zones] and one for water.

    Thank you in advance

    D

  2. #2
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    Quote Originally Posted by Dubdubz View Post
    Hello

    I have had Evohome for over a year and it has been working flawlessy...until I tried to add the hot water kit tonight?
    No matter what I seemed to select the Bolier relay BDR91 and the seperate hot water BDR91 seemed to merge when testing the RF?

    Background...
    I had originally an S+ system with a zone valve for upstairs and a zone valve for downstairs and a valve for the heating.

    I converted it to a valve for the hot water with a Honeywell timer type controller - disconnected the wiring to the heating valves and wired them open.
    I then have a BDR91 operating as a boiler relay.

    I searched for an hour trying to locate a wiring diagram for what I need but at a loss - any pointers?
    I need to keep the motorised valve for the water of course - so I cant see the option I need. Boiler Relay and single 2port valve?


    [I did at one time have a BDR91 connected to the heating zone valves but that seemed to break the BDR91 so I converted to a boiler relay setup]

    I am happy to adjust the pipework if I need to but please do remember I have 2 pipes - 2 zone valves for the heating, they are next to each other; if I had to introduce one valve for heating [feeding the 2 pipe zones] and one for water.

    Thank you in advance

    D
    There is a sequence to follow and when configuring the Evohome system if you are adding domestic hot water then you configure that and itís relay first. Once done you then add your zones and valves. It may be you have tried to add DHW to an already configured system. If so try starting afresh, clear out all existing pairings etc. reset and then start again by adding the hot water provision first.

  3. #3
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    Quote Originally Posted by G4RHL View Post
    There is a sequence to follow and when configuring the Evohome system if you are adding domestic hot water then you configure that and itís relay first. Once done you then add your zones and valves. It may be you have tried to add DHW to an already configured system. If so try starting afresh, clear out all existing pairings etc. reset and then start again by adding the hot water provision first.
    Thanks I was trying to add DHW to an existing system.
    I ended up having to start afresh (somehow in my increasing temper! :-/ ) to wipe all the zones and then I also put back the DHW as it was.

    So I reset completely?
    Add DHW
    Then do the zones ? With the heat as boiler relay?

    Will it need to do all the learning again, this seems so backwards and has really taken the shine off for me.

    Thank you in advance. If I have to start afresh then I will but I only really want to do once more

    Oh and is there a Ďsaveí option anywhere so I could restore back to a previous if I wiped the zones? Guessing not.

  4. #4
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    I made the same mistake when I installed my Evohome system 5+ years ago. A careful re-read of the manual and I realised I had the sequence wrong. Caused by my enthusiasm to have all running and thinking the DHW was a side issue. So it meant wipe everything and starting right from scratch to ensure I had not other errors. Hot water first, then the CH. no problems since. The manual is poorly written. Something as fundamental as this should be given greater prominence. Indeed, the manual should be easier to understand anyway. Yes, all will probably be wiped and optimisation, if you use it, starts again. I don’t use it as it made no difference. Just no benefits from having it. Being able to save settings would be a nice bonus, but to save what you know is fully functioning and not a system that may have flaws! Good luck, take your time and a re-read of the manual slowly may be helpful. As said, I think the manual is very poor.

  5. #5
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    Quote Originally Posted by G4RHL View Post
    I made the same mistake when I installed my Evohome system 5+ years ago. A careful re-read of the manual and I realised I had the sequence wrong. Caused by my enthusiasm to have all running and thinking the DHW was a side issue. So it meant wipe everything and starting right from scratch to ensure I had not other errors. Hot water first, then the CH. no problems since. The manual is poorly written. Something as fundamental as this should be given greater prominence. Indeed, the manual should be easier to understand anyway. Yes, all will probably be wiped and optimisation, if you use it, starts again. I donít use it as it made no difference. Just no benefits from having it. Being able to save settings would be a nice bonus, but to save what you know is fully functioning and not a system that may have flaws! Good luck, take your time and a re-read of the manual slowly may be helpful. As said, I think the manual is very poor.
    thank you

    sorry for asking the same question again - when you say zones do you mean the rooms with the 92's on?
    I'm wondering if I can wipe the boiler relay and do DHW then add boiler relay but keep the rest of the rooms - I have 9 rooms to do so it is a ball ache!
    [but if that is what I need to do!] I have found the diagram BUT the boiler relay is missing from it - its Sample Evo systems fig 4 - Stored Hot Water and zoned heating system.


    The boiler relay is in the airing cupboard - a hang over from when I had this operating the 2 CH 2 port valves - so I might move that next to the boiler and then start from scratch.

    When you mention optimisation what do you mean as I thought irrespective it learnt the thermal properties of a given room to work out if you want it 20deg at 6am that it needed to start at 5.15 as an example

  6. #6
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    Quote Originally Posted by Dubdubz View Post
    Hello

    I have had Evohome for over a year and it has been working flawlessy...until I tried to add the hot water kit tonight?
    No matter what I seemed to select the Bolier relay BDR91 and the seperate hot water BDR91 seemed to merge when testing the RF?
    When you do the RF test it always makes the light on all BDR91's flash together no matter whether you "test" the heating or hot water relays. It's just a quirk - our systems all do that too. So you can't use the RF test as a method to confirm that you have bound the right relays to the right function, it's only useful for measuring signal levels.

    If you're unsure, remove the bindings and re-bind them. Remember when you do this you must remove bindings at both ends - on the BDR91 it's a 15+ second press of the button until you get a rapid flash, on the Evohome side set hot water to disabled and boiler relay to none, this will clear the previous bindings without losing your heating zone schedules and configuration. (Hot water configuration will be lost though)

    If you don't clear the bindings on the BDR91 you can end up with the relay being bound to multiple functions, so be careful.
    Background...
    I had originally an S+ system with a zone valve for upstairs and a zone valve for downstairs and a valve for the heating.

    I converted it to a valve for the hot water with a Honeywell timer type controller - disconnected the wiring to the heating valves and wired them open.
    I then have a BDR91 operating as a boiler relay.
    So far so good...although keep in mind that with your heating zone valves wired open, when the hot water is reheating it will cause your boiler to operate at full set flow temperature - this might lead to a bit of temperature overshoot in rooms.

    I searched for an hour trying to locate a wiring diagram for what I need but at a loss - any pointers?
    I need to keep the motorised valve for the water of course - so I cant see the option I need. Boiler Relay and single 2port valve?

    [I did at one time have a BDR91 connected to the heating zone valves but that seemed to break the BDR91 so I converted to a boiler relay setup]

    I am happy to adjust the pipework if I need to but please do remember I have 2 pipes - 2 zone valves for the heating, they are next to each other; if I had to introduce one valve for heating [feeding the 2 pipe zones] and one for water.
    Generally if you have an S-Plan system and two BDR91's you do not configure a boiler relay. (Set it to none) You should go through stored hot water and bind a hot water relay (for your hot water zone valve) and a heating zone relay for heating.

    You would wire the heating zone relay to both of your heating zone valves in your S+ system - the upstairs and downstairs ones, so they open and close together. There is no need for them to open independently of each other when the HR92's now perform the zoning, however it is useful for them to be able to close in a TPI cycle when heating demand is low and hot water is being reheated to minimise any room overshoots during hot water heating.

    If the wiring for both upstairs and downstairs zone valves come back to the same wiring centre simply wire them in parallel to be switched by the same BDR91. In the event that the wiring can't come back to the same location you can use a second BDR91 and bind both BDR91's as heating zone valves.

    To fire the boiler you would use the switch contact out of the heating zone valves - again I would parallel them up if possible (for redundancy) so either zone valve can fire the boiler.

  7. #7
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    Quote Originally Posted by DBMandrake View Post
    When you do the RF test it always makes the light on all BDR91's flash together no matter whether you "test" the heating or hot water relays. It's just a quirk - our systems all do that too. So you can't use the RF test as a method to confirm that you have bound the right relays to the right function, it's only useful for measuring signal levels.
    I really did not know this ... and this was the reason for me to wipe my system [like a goon] as I thought that I had somehow managed to configure both to do the same job!
    This is a real flaw as when you are in the panel and you are checking the RF for a specific controller - you would not expect it to flash both...just the one you had selected.

    Quote Originally Posted by DBMandrake View Post
    If you're unsure, remove the bindings and re-bind them. Remember when you do this you must remove bindings at both ends - on the BDR91 it's a 15+ second press of the button until you get a rapid flash, on the Evohome side set hot water to disabled and boiler relay to none, this will clear the previous bindings without losing your heating zone schedules and configuration. (Hot water configuration will be lost though)
    This news is great so I can re state my BDR91's to the right functions - ignoring the RF test as this is dumb!

    Quote Originally Posted by DBMandrake View Post
    So far so good...although keep in mind that with your heating zone valves wired open, when the hot water is reheating it will cause your boiler to operate at full set flow temperature - this might lead to a bit of temperature overshoot in rooms.
    Thanks for this I wasn't aware of this point, I hadn't noticed overshoot but also I havent plugged in domitiz or whatever it is!

    Quote Originally Posted by DBMandrake View Post
    Generally if you have an S-Plan system and two BDR91's you do not configure a boiler relay. (Set it to none) You should go through stored hot water and bind a hot water relay (for your hot water zone valve) and a heating zone relay for heating.
    Can I do this as I have it now - you mentioned earlier that I could just remove my binding to the heating boiler relay...
    then add the DHW
    then add the bdr91 wired to the 2x heating zone valves ?
    - it must have just been my incorrect thoughts I had presumed that the BDR91 failed due to the load of opening 2 valves.[I had it wired parallel into the CH valves originally for about a year]
    It might have just been a natural failure?

    Quote Originally Posted by DBMandrake View Post
    You would wire the heating zone relay to both of your heating zone valves in your S+ system - the upstairs and downstairs ones, so they open and close together. There is no need for them to open independently of each other when the HR92's now perform the zoning, however it is useful for them to be able to close in a TPI cycle when heating demand is low and hot water is being reheated to minimise any room overshoots during hot water heating.
    TPI cycle - I am maybe reading it wrongly but are you saying that I should wire them so they open together or do it a different way and if so how do I wire that! :-)
    Quote Originally Posted by DBMandrake View Post
    If the wiring for both upstairs and downstairs zone valves come back to the same wiring centre simply wire them in parallel to be switched by the same BDR91. In the event that the wiring can't come back to the same location you can use a second BDR91 and bind both BDR91's as heating zone valves.

    To fire the boiler you would use the switch contact out of the heating zone valves - again I would parallel them up if possible (for redundancy) so either zone valve can fire the boiler.
    yes the wiring for both do indeed terminate in one wiring centre - could you message me a scribble drawing so I perhaps understand it better?

    I am so impressed by this forum - it has been extremly useful when I installed my system way back when and now it has come into its own with friendly and informative advice - with none of the 'get a professional in' or 'if you don't know what you're doing' type posts!!
    Everyone has to learn - no one was born with the ability to install and wire in Evohome!

    thank you!

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