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Thread: New EvoHome and HR92s with existing plumbed two zone CH

  1. #1
    Automated Home Jr Member
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    Default New EvoHome and HR92s with existing plumbed two zone CH

    Hi,

    Thanks to a failed oil boiler, I took the opportunity to replace the 20-year old heating controls with a system based around the new colour EvoHome. Our plumbed system consists of a single boiler that outputs to two CH zones (downstairs and upstairs) and HW.

    Here's how it's configured (Phase 1) and what I want to achieve (Phase 2):

    Phase 1 (completed)
    Downstairs - Evohome controller thermostat bound with BDR91 controlling downstairs CH valve.
    Upstairs - DT92E digital thermostat bound with BDR91 controlling upstairs CH valve.
    Hot water tank - CS92 thermostat (attached to tank) bound with BDR91 controlling HW valve.

    Phase 2 (to be done)
    Upstairs - Replace DT92E digital thermostat with HR92 radiators TRV's

    Is Phase 2 possible in a 2-zone plumbed CH configuration? Found the Evohome help line useless as they told me I had an unusual configuration and needed expert assistance. I find this hard to believe as the system to far has been simple to configure and design with help from a qualified electrician.

    Any guidance appreciated. The system is working so well so far, I will be gutted if the 2nd phase won't work.

  2. #2
    Automated Home Lurker
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    Are you currently using the switched live feed from the zone valves (orange wire) to give boiler demand?

    If HR92's are fitted to every radiator on the Upstairs, this will actually negate the requirement for a zone valve entirely (as each radiator controller is effectively a zone valve). This will give you the option of using a BDR91 as a boiler relay (as it comes out of the Base Pack box) and zoning your downstairs with the one zone valve controlled by the BDR91/evohome Controller and which will allow you to electrically disconnect the upstairs zone valve and leaving it in the manually open position will allow the HR92's to work.

    As for Honeywell, they will not give technical advice to non trained/recognised evohome installers which I am...
    Gas Safe & OFTEC registered - Honeywell Recognised evohome Installer - Always lurking on Twitter!

  3. #3
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    Welcome to the club, I have also just installed an Evohome colour.
    I have a "standard" "y" plan, ie hot water and one central heating zone.

    The issue I am having is that when the hot water relay demands heat, the heating relay also demands heat. The other way round ie heating demanding heat, everything works OK.

    I phoned the helpdesk and they have advised that, as I have the BDR9 relays relays next to each, other I should move them apart. However, I don't believe they are interfering with each other because:

    1 The heating relay does not trigger the hot water relay
    2 Sometimes you can see the heating relay come on about half a second before the hot water relay, implying that the request is coming from the control and not any interference from the hot water relay.

    Tonight I am going to put one of the BDR9 on an long piece of cable and rule out interference, but I would be interested to know if anyone else has had this problem?

    Ian

  4. #4
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    Hi Rich,

    I will need to check on the wiring and get back to you.

    Are you saying that Honeywell advises its installers to convert existing zoned CH (upstairs/downstairs) with two valves, to a single valve for use with Evohome and HR92's? It seems odd that the Evohome system hasn't been designed with this scenario in mind. It troubles me that CH is going to pumped around the house when any HR92 demands more heat. Perhaps I'm misunderstanding or worrying overly at the cost of heating the floor pipework.

    Your thoughts are appreciated.

    Thanks,
    Heath

  5. #5
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    Hi Ian,

    I can't help on the wiring, but it's possible they've been incorrectly wired. I have 3 x BDR91's next to each other and I have no issues. I did make sure they were installed at a distance (see the manual for specifics) from the boiler/metal objects.

    Although, soon after installation I may have inadvertently messed up the config, so I followed the manual and reset all the BDR's and reconfigured them which was 10 minutes work. I then controlled the heating from the Evohome controller and watched the CH and HW valves to ensure all was responding ok. Since then I haven't seen any issues.

    Heath

  6. #6

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    Evo does only support control of a single heating zone valve when using HR92s, it does not allow rooms to target different zone valves (such as when the ground and first floor are separately). Providing all radiators are fitted with HR80s or HR92s this is not of much consequence. However if only some radiators are directly controlled and discrete control over the 2 zone valves is still required then the only option is to run two Evo controllers, one for each floor.

    Honeywell are trying to keep the Evo system relatively easy to implement but maintain a decent degree of flexibility, so they have no plans to change this approach (which has been their position since the early days of Hometronic when we first raised this issue with them).
    Last edited by SensibleHeatUK; 6th May 2014 at 07:37 PM.
    Sensible Heat
    SensibleHeat.co.uk

  7. #7
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    Quote Originally Posted by HeathU View Post
    Hi Ian,

    I can't help on the wiring, but it's possible they've been incorrectly wired. I have 3 x BDR91's next to each other and I have no issues. I did make sure they were installed at a distance (see the manual for specifics) from the boiler/metal objects.

    Although, soon after installation I may have inadvertently messed up the config, so I followed the manual and reset all the BDR's and reconfigured them which was 10 minutes work. I then controlled the heating from the Evohome controller and watched the CH and HW valves to ensure all was responding ok. Since then I haven't seen any issues.

    Heath
    I'm 99.9% sure they are wired up correctly, so I think I will try a factory reset. I never had this problem, until I installed the HR92's which arrived today, so it might be a software glitch.
    (As an update I forcibly turned off the heating, by pushing the button on the BDR9, but it it looks like the controller sends out regular heartbeats and has turned d it on again).

    Ian

  8. #8

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    You need to register the heating BRD as a sundial heating valve so that it only responds to heating demands and not as a boiler relay.

    A boiler relay responds to heating and hot water demand, so would be registered as a boiler relay only if there was no end switches fitted to or wired from the 2-port zone valves.
    Sensible Heat
    SensibleHeat.co.uk

  9. #9
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    Quote Originally Posted by SensibleHeatUK View Post
    Evo does only support control of a single heating zone valve when using HR92s, it does not allow rooms to target different zone valves (such as when the ground and first floor are separately). Providing all radiators are fitted with HR80s or HR92s this is not of much consequence. However if only some radiators are directly controlled and discrete control over the 2 zone valves is still required then the only option is to run two Evo controllers, one for each floor.

    Honeywell are trying to keep the Evo system relatively easy to implement but maintain a decent degree of flexibility, so they have no plans to change this approach (which has been their position since the early days of Hometronic when we first raised this issue with them).
    This is a phased deployment. The upstairs radiators have been replaced and have new Honeywell manual valves ready for the HR92's. I've left the downstairs CH zone controlled by the Evo controller as at a later date I may replace the radiators with UFH. I wouldn't consider a 2nd Evo controller as I'd end up with two different configurations and the remote RFG100 only supports one Evo controller.

    I still think this is an odd decision from Honeywell as a lot of new buildings are being plumbed with multiple zones from new. Seems crazy to heat areas of the house that don't need it. Their web site configuration tool doesn't mention it nor does any other Q&A on the web site.

  10. #10

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    This is not a UK specific control system, but a Europe-wide platform, and we are the only country to "fudge" energy efficiency/building regs by adopting the S-Plan Plus approach. Honeywell argue that if you are controlling every room as a zone then the fact that you have two heating zone valves is not an issue as they can either be operated together or even removed as the zone control is now carried out at room level (and it does not matter what form of heating is used either).

    It is only when you do not control every room or heat emitter that it becomes a problem, so if you use Evo you then need to decide what you want to do to make your system fit the restrictions imposed by the decisions Honeywell have made. I doubt Honeywell will spend any development time or money to change just for the UK when this can be dealt with by using more of their controls (every room fully controlled), by using two Evo controllers, or by simplifying the control approach to keep control at zone-valve level (I.e. the current building regs standard).
    Sensible Heat
    SensibleHeat.co.uk

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