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Thread: Evohome Temperature Sensor Not Updating Controller

  1. #21
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    Yes, it makes sense that the Heating will run on to maintain a smooth heating line. Still a little perturbed that the Heating did not switch off immediately when told to, don't like the idea of heating remaining on when it should be off but will need to adjust to the latency of the Evohome system.

    Hot Water has been a real problem. When first installed never had an issue. But recently it has been playing up. On several occasions, yesterday and this morning the hot water has just been stuck on a low temperature for hours. Even switching the Hot Water on at the BDR91 manually did not seen to achieve anything.

    I removed batteries form the CS92 but that did not seem to achieve anything. I rebooted the Controller and that seemed to do the trick but the Heating was reading perfectly. Same problem again this morning. Removed batteries from CS92 and removed the PCB and bent the pins on the PCB contacts. Reassembled, put batteries in and no joy. I did not do a rebind...maybe I should.

    Getting a bit hacked off with Evohome. When it works it is great and I have had no issues with the Heating other than the latency issue which is a lack of understanding on my part. But having no hot water is not good especially if I need to grab a shower before I go to work to find it is luke warm.

    So, I have removed batteries/replaced them. Battery strength is fine. Adjusted terminals on PCB. And still no luck. Any ideas?

  2. #22
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    Quote Originally Posted by MasterChief View Post
    Yes, it makes sense that the Heating will run on to maintain a smooth heating line. Still a little perturbed that the Heating did not switch off immediately when told to, don't like the idea of heating remaining on when it should be off but will need to adjust to the latency of the Evohome system.
    There is an up to 5 minute delay between changing set points on the controller and having them take effect. That's just the way the system works and can't be avoided. More than 5 minutes suggests a problem though.
    Hot Water has been a real problem. When first installed never had an issue. But recently it has been playing up. On several occasions, yesterday and this morning the hot water has just been stuck on a low temperature for hours. Even switching the Hot Water on at the BDR91 manually did not seen to achieve anything.
    Ok first of all and most importantly, was the hot water actually at a low temperature (as felt at the tap) or was it only reporting a low temperature on the controller ? The outcome of that question leads to two very different diagnoses.

    You say you manually turned on the hot water BDR91 - I assume you just have a two relay configuration not three like mine, did the boiler fire 15 seconds after manually activating the relay ? If not that suggests a problem with your zone valve or something other than Evohome. Are you sure your zone valve opened and the boiler fired when you did this manual override ? And did you check the temperature of the water at the tap after 10 minutes or did you just look at the reading on the controller ?
    I removed batteries form the CS92 but that did not seem to achieve anything. I rebooted the Controller and that seemed to do the trick but the Heating was reading perfectly. Same problem again this morning. Removed batteries from CS92 and removed the PCB and bent the pins on the PCB contacts. Reassembled, put batteries in and no joy. I did not do a rebind...maybe I should.

    Getting a bit hacked off with Evohome. When it works it is great and I have had no issues with the Heating other than the latency issue which is a lack of understanding on my part. But having no hot water is not good especially if I need to grab a shower before I go to work to find it is luke warm.

    So, I have removed batteries/replaced them. Battery strength is fine. Adjusted terminals on PCB. And still no luck. Any ideas?
    You really need to identify whether your problem is the true temperature of the cylinder being reported back to the controller or whether the issue is on the control side. (relay/zone valve/boiler/cylinder)

    You say the water is luke warm, what temperature did the evohome report when it felt luke warm ? When it was luke warm and scheduled to be hot was the hot water BDR91 light on ? If it was this pretty much rules out most of the Evohome as the problem - it is reporting the temperature is too low and firing the hot water relay - that's all it can and should be doing if the water needs heating up.

    So if the light was lit on the BDR91 and your water remained luke warm after 10-20 minutes you either have a faulty BDR91 (faulty relay contacts) a wiring fault or mistake, a faulty hot water zone valve, a plumbing problem - something of that nature.

    I did have problems with hot water control but for me it was always temperature overshoots (hot water about 12 degrees hotter than desired) due to the sensor not reporting in often enough during a re-heat. I've never had problems with hot water remaining cold when it should be heating up, and now that I've moved the CS92 location and adjusted the battery contacts on the PCB my overshoot problems have all but disappeared.
    Last edited by DBMandrake; 10th December 2016 at 11:58 AM.

  3. #23
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    Thanks for the rapid reply DBMandrake and thanks for your help to date.

    I think Heating is okay and within tolerance (5 mins). Just my lack of understanding so thanks for the heads up.

    Okay, I did have a plumber come in recently to fix the 3-way zone valve...the synchron motor had gone so he replaced it. But there would have been no need to adjust any wiring as the 3-way valve controller was retained. But I will need to do some tests to see if it is an Evohome problem or something else.

    When the water was lukewarm and reporting 18 degrees, the Hot Water BDR91 was on (green light illuminated) and I assumed the water temperature was incorrect. I put the shower on and it was barely warm so Evohome was reporting the correct temperature. So, maybe the 3-way valve still has an issue, perhaps a faulty Synchron Motor which is not opening up fully. I checked there was play in the spindle in the 3-way valve so I know it is not a stuck spindle. It is an intermittent problem which could well point to a faulty Synchron Motor but as it has just been replaced I simply assumed it could not be that.

    When BDR91 is on, the boiler fires and the pump starts so that is all fine. Looks like I will need to get the plumber back to investigate the 3-way valve again. Bother!

    Although a mechanical problem is preferred as this would explain why it used to work and then stopped albeit intermittently.

    I will report back once the plumber has come back.

  4. #24
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    Quote Originally Posted by MasterChief View Post
    Okay, I did have a plumber come in recently to fix the 3-way zone valve...the synchron motor had gone so he replaced it. But there would have been no need to adjust any wiring as the 3-way valve controller was retained. But I will need to do some tests to see if it is an Evohome problem or something else.
    Do you know if your three port zone valve is a mid position valve or just a hot water priority valve ?
    When the water was lukewarm and reporting 18 degrees, the Hot Water BDR91 was on (green light illuminated) and I assumed the water temperature was incorrect. I put the shower on and it was barely warm so Evohome was reporting the correct temperature.
    Sounds to me like the Evohome system was working properly in that instance, it was correctly reporting the water was cold and it had turned the hot water relay on in an attempt to warm it up. If after 10 or so minutes of that BDR91 being on the water was still no hotter then unless the actual relay contact in the BDR91 was faulty and not switching on when the light was green (which is possible but pretty unlikely) then the problem lies somewhere else.
    So, maybe the 3-way valve still has an issue, perhaps a faulty Synchron Motor which is not opening up fully. I checked there was play in the spindle in the 3-way valve so I know it is not a stuck spindle. It is an intermittent problem which could well point to a faulty Synchron Motor but as it has just been replaced I simply assumed it could not be that.

    When BDR91 is on, the boiler fires and the pump starts so that is all fine. Looks like I will need to get the plumber back to investigate the 3-way valve again. Bother!
    Do you rely on a contact in the zone valve to fire the boiler (orange wire) or does your boiler relay directly fire the boiler ?

    This may depend on whether your zone valve is mid position or hot water priority. On a mid position valve the default unpowered position of the valve is hot water only, however on a hot water priority valve I think the default mechanical position is heating.

  5. #25
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    It is a Mid-Position Valve so can deliver hot water and heating at the same time. When the motor failed recently it was stuck in the heating only position.

    The BDR91's (on for Hot Water and one for Heating) both connect to the 3 Way Valve so it is the orange wire that is used to fire the boiler.

    Hot Water is working fine again now.

  6. #26
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    Are you sure the hot water heats up both if the central heating is on and if it is off ?

    Mid position valves are quite complicated both mechanically and electrically so there is a lot to go wrong with them that could cause subtle symptoms, and they're not easy to troubleshoot.

    There's a good explanation of how they work here:

    http://www.diyfaq.org.uk/plumbing/co...itionvalve.htm

    And an example of how they are normally wired here:

    http://wiki.diyfaq.org.uk/index.php?..._zones:_Y-plan

    Is yours a Honeywell valve or some other brand ?

    Next time the hot water is not heating but should be (hot water relay and boiler both on with hot water temperature below your target) I would check the pipe run from the mid position valve to the hot water cylinder near the middle of the run and see if it feels hot - if not then that would give an indication that hot water is not being pumped to the cylinder indirect loop.

  7. #27
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    It is a Honeywell V4037A 3-Port Valve.

    It is difficult to check because the run from the valve to the cylinder is pretty short. So, any heating flow to the radiators will result in the hot water feed pip heating up.

    But I will check as near to the cylinder as I can. I will also see if there is any difference if hot water is on alone and where both heating and hot water are on.

    I did check the wiring earlier and it looks good at the 10 terminal wiring block. I have not checked the BDR91 wiring so may check them tomorrow.

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