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Thread: Just installed Evohome... couple of questions

  1. #1
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    Default Just installed Evohome... couple of questions

    Hi all,

    So have just spent the last few hours installing the Evohome controller, hot water pack and five HR92's.

    I have no boiler relay, instead the "Heating" BDR91 controls a pair of V4043 zone valves (wired in parallel) and the "Hot Water" BDR91 controls a third V4043 for DHW. Condensing boiler is activated by the end switches.

    Everything seems to be connected up ok. Hot water is working beautifully. However the relay for heating seems to have a bit of a mind of its own. It switches on and opens the CH zone valves even when I've set the controlled to "Heating Off", as shown below:

    IMG_6033.jpg

    If I push the button on the BDR91, it turns off and closes the zone valves and the boiler stops. But it shouldn't have been on in the first place! And it'll come on again a few minutes later (I don't know why!)


    I'm not sure I have it configured correctly on the Evohome controller. When doing the guided configuration I said I have 2 zone valves controlling CH and DHW. It then asked me to bind the hot water sensor and both BDR91's in turn, all of which was successful.

    However, I'm not sure I have this part set right -

    IMG_6034.jpg

    Should I have "Boiler Demand" set to "Boiler Relay", even though it's controlling the zone valve only?

    Any advice appreciated!

    Thanks,

    Gareth
    Last edited by garmcqui; 10th January 2015 at 04:36 PM.

  2. #2
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    Have just tried setting the "Boiler Demand" to "Boiler Relay", it asks me to bind the BDR91 again (successful).

    However, with it set like this, if I just ask for hot water, both BDR91's activate (as the CH one thinks it is controlling the boiler).

    I'm confused.

  3. #3
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    Quote Originally Posted by garmcqui View Post
    Should I have "Boiler Demand" set to "Boiler Relay", even though it's controlling the zone valve only?
    As I understand it your original setup was correct. The BRD91 should not be set as a Boiler Relay because it is not required to generate a call for heat as an OR function of the two heating demands (CH and HW), this is already done by the parallel connection of the switches in the 3 zone valves.

    Quote Originally Posted by garmcqui View Post
    If I push the button on the BDR91, it turns off and closes the zone valves and the boiler stops. But it shouldn't have been on in the first place! And it'll come on again a few minutes later (I don't know why!)
    From other threads it would seem there is a "keep alive" function which continually refreshes the BRD91 commands and will turn it back on if you override it with the button. I will be interested in other replies as I too have unexplained operation of a BRD91 under a variety of circumstances, see separate posting.

    HTH, Chris

  4. #4
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    Quote Originally Posted by garmcqui View Post
    Hi all,

    So have just spent the last few hours installing the Evohome controller, hot water pack and five HR92's.

    I have no boiler relay, instead the "Heating" BDR91 controls a pair of V4043 zone valves (wired in parallel) and the "Hot Water" BDR91 controls a third V4043 for DHW. Condensing boiler is activated by the end switches.

    Everything seems to be connected up ok. Hot water is working beautifully. However the relay for heating seems to have a bit of a mind of its own. It switches on and opens the CH zone valves even when I've set the controlled to "Heating Off", as shown below:

    IMG_6033.jpg

    If I push the button on the BDR91, it turns off and closes the zone valves and the boiler stops. But it shouldn't have been on in the first place! And it'll come on again a few minutes later (I don't know why!)


    I'm not sure I have it configured correctly on the Evohome controller. When doing the guided configuration I said I have 2 zone valves controlling CH and DHW. It then asked me to bind the hot water sensor and both BDR91's in turn, all of which was successful.

    However, I'm not sure I have this part set right -

    IMG_6034.jpg

    Should I have "Boiler Demand" set to "Boiler Relay", even though it's controlling the zone valve only?

    Any advice appreciated!

    Thanks,

    Gareth
    Hi Gareth,

    Your evohome setup was correct in the first place and now by adding a 'boiler relay' you have double (if not triple) bound the Heating BDR91 relay.

    To 'ensure' things are working correctly, read my post on our website regarding BDR91 installation and binding - http://www.theevohomeshop.co.uk/evo-help/

    In this case to try and eliminate errors, try and keep things simple to start to ensure the system is working correctly - so do a full factory reset of everything and bind in 1x HR92 only. Do this as follows...

    1. 'FACTORY RESET' evohome Controller and then 'HARD RESET' by removing batteries for several minutes.
    2. Fully clear the 'binding' on both BDR91's (press and hold the button on the BDR91 for 20 seconds).
    3. Fully clear the 'binding' on the HR92's (press, then press and hold the info/function button until you get 'BIND' then press and hold the button again for about 15 seconds until 'CLEARED' is shown)
    4. Fully clear the 'user menu' on the HR92's (press and hold the info/function button until the user menu is displayed, turn adjustment dial to parameter 12.0, press button and change this to 12.1 and press button again then turn dial to exit).
    5. Rebind through 'GUIDED CONFIGURATION' and then 'STORED HOT WATER CONFIGURATION' first.
    6. When prompted, bind the CS92 as per page 16 of the evohome Installation Guide.
    7. Choose the correct system configuration (in your case S Plan/2 port motorised zone valves)
    8. Bind the hot water & heating BDR91's when prompted to, as per page 17 of evohome Installation Guide.
    9. Once complete, bind in only 1x HR92 using 'GUIDED CONFIGURATION' and then 'ZONE CONTROL CONFIGURATION'.
    10. When it asks 'Do you require to control the heat demand (boiler)?' press the RED 'CROSS' BUTTON.
    11. Press 'RADIATOR VALVE' button.
    12. Choose '1' and then press grey right hand arrow button.
    13. Rename the zone to what you want it to be, then press the right hand arrow button.
    14. Choose if you want to use the evohome Controllers internal sensor for this zone or not, remember this can only be done once! I don't personally use the internal sensor for any zone and if the HR92 is not suitably located use a DTS92 or T87RF as the sensor.
    15. Bind in a HR92 as per page 14 of the evohome Installation Guide (when the 'SUCCESS' message is shown on the HR92, wait 3-4 seconds before pressing the tick button on the evohome Controller).
    16. Add additional HR92's to the zone or press the RED CROSS BUTTON if this is the only HR92 in that zone.
    17. Guided configuration will now be complete, so completely exit the 'INSTALLATION MENU'.
    18. Check/test the system works 100% - do this by increasing and decreasing the bound HR92's temperature and within 5 minutes the 'Heating BDR91' should come on/off and then turn the hot water on/off to see if the 'Hot Water BDR91' turns on and off (obviously if the hot water cylinder is up to temperature it will do nothing).
    19. If everything is OK, go back into the 'INSTALLATION MENU' and now add the other zones using the 'ADD ZONE' button (bottom left hand button). Do not use 'GUIDED CONFIGURATION' to add the new zones otherwise you will remove everything you have done and will end up 'double binding' items.

    Please ensure the temperature in hot water cylinders are set at 60 degrees Celsius (not the 50 degree Celcuis evohome Controller default) in the 'PARAMETER SETTINGS' menu, to ensure you kill Legionella bacteria (cause of Legionnaires' disease)! More details of Legionella in water systems on HSE's website - http://www.hse.gov.uk/healthservices/legionella.htm

    Hope that helps.

    Thanks,

    Richard.

  5. #5
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    OK, many thanks to all of you for replying.

    After following Richard's excellent advice above, I *think* it's working properly now.

    One thing I was surprised about was how long it takes for the controller to sync with the HR92's and Hot Water Sensor after a hard reset - 15mins later and it was still waiting for sync on some!

    Another thing I'm anxious about - the original cylinder thermostat I removed was a dual thermostat (ie: safety cut off stat too). Since I have an unvented cylinder, I read that I need to get one to work with Evohome, however I can't find any information about it anywhere now! Any ideas?

    Thanks!

  6. #6

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    You do need to refit your control/high limit stat ASAP as it is a mandatory safety device for unvented cylinders. What you ought to have done is wired the Evo BDR in series with the existing stat and turned the control stat temperature setting to maximum so that Evo was in control.
    Sensible Heat
    SensibleHeat.co.uk

  7. #7
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    ok thank you, so as a matter of priority I need to get it sorted.

    What you ought to have done is wired the Evo BDR in series with the existing stat and turned the control stat temperature setting to maximum so that Evo was in control.
    But if I left the existing stat in, where would the Evohome probe have gone?

    This is the current setup:

    IMG_6041.jpg

    So as you can see there is a spare space for a second high limit stat at the top of the cylinder.

    This is the stat I took out:

    IMG_6044.jpg IMG_6045.jpg

    Can I do anything with this? If not, can anyone recommend a suitable high limit stat to wire in series with the BDR91?

    Thanks!

    PS: Or I suppose I could replace the original thermostat, wire it in series with the BDR output, and insert the Evo temperature prove into the spare well at the top. The only downside being that it will be measuring the hottest part of the tank, so the hot water setting in the Ebohome comtroller would need to be something silly like 75C?
    Attached Images Attached Images
    Last edited by garmcqui; 11th January 2015 at 01:29 PM.

  8. #8

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    If your safety thermostat at the top of the tank is wired in series with the hot water BDR (so that if the safety sat trips the hot water 2-port valve shuts straight away) then you are fine - most pressurised cylinders have a single combined control & safety stat only, so when you mentioned that is what you had removed I assumed there was no other stat to give you high limit protection.

    Fitting an additional sensor to a mains-pressure cylinder is always difficult. You can sometimes fit the bead sensor in the same pocket as the thermostat but not always. I've seen some jobs where the outer jacket and installation have been cut out and replaced after the sensor probe is fitted, and on others I've seen sensors clamped to the hot water pipework as it leaves the cylinder (not a bad alternitive location if there is also a hot water secondary pump in operation). At the end of the day hot water temperature control is not quite so critical for most people, so providing the temperature measured is consistent with the bulk tank temperature then a slightly sub-optimal sensor location with an appropriate setpoint is not necessarily a bad thing.

    Where it is not possible to get a decent sensor location then the control stat can always be retained as the controlling mechanism with the Evo sensor used for monitoring instead - in this case Evo acts more like a timeclock and and the stat closes the 2-port valve when the required temperature is reached (thereby removing the demand to the boiler).
    Sensible Heat
    SensibleHeat.co.uk

  9. #9
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    I see what you're saying.

    However, tracing the wiring back from the existing safety thermostat (at the top of the tank) it appears like it is purely for the solar heating system, which is seperate from the DHW (boiler) system. So this thermostat is not providing any safety unless it's extremely sunny (not likely in Newcastle!).

    I've now refitted the dual control/safety stat in its original place and set the dial to 60C.

    I've placed the Evohome temperature probe in the spare well at the top of the tank. The tank is warming up and I'm waiting to see what temperature the Evo probe reads at the top of the tank when the control stat interrupts the boiler demand (currently saying 72C).

    I can't see the top of the tank being over 85C (Evo's highest setting) when the middle of the tank is at ~60C. We'll see.

    Thanks again,

  10. #10
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    Before I had My Evohome system installed, I rang OSO for advice on how to fit the HW kit to my unvented HW cylinder. First of all, they gently reminded me that only an engineer with a G3 certificate could legally work on an unvented tank. When we had got over that hurdle, they helpfully suggested that the probe would work if it was pushed up between the foam insulation and the inner tank via the electrical access panel. This solution has worked well.

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