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Thread: Evohome CS92 troubles

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  1. #1
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    Default Evohome CS92 troubles

    After over a year of more or less trouble free Evohome living, the system has started to throw problems with the CS92 wireless thermostat for the hot water.

    Every so often there will be a period where the controller shows a comms error with the sensor, and this may be anything from a few minutes to a few hours. Take a battery out of the sensor and pop it back in and the temperature is immediately displayed on the controller again. Ive tried changing batteries and even repositioning the CS92. There is now only one wall between the CS92 and the controller. A signal test shows either excellent or good communication.

    Works fine for a while (anywhere from a few hours to a day), and then the comms errors start again. This causes major annoyance when it occurs just before the hot water is set to heat ready for showers on the morning. Cold water on the morning the missus is up early to wash hair is not the best way to start a day I can tell you.

    I cant think of any changes in the room that would interfere with the comms, and certainly not at the random times the errors occur. The signal strength is fine when doing a test, either four or five flashes on the CS92 and excellent or good on the controller. A simple remove and reinsert of either battery and its all back and running fine again.

    Can anyone think of anything that I may be able to check as to why this has started? Hot water has been fine for months on end until now.

  2. #2
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    sounds Like a Bad connection on CS92 Board there is a thread here where people opened the CS 92 Bent Spring Contacts and reassembled and this resolved their Issues worth looking at

    http://www.automatedhome.co.uk/vbull...highlight=CS92

  3. #3
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    I suggested in this thread that we were being lulled into a false sense of CS92 happiness while our heating was off over the summer:

    http://www.automatedhome.co.uk/vbull...ershoots/page3

    Like you, mine had been working fine for the last couple of months while my heating was off but my heating is back on for the autumn and this morning I had an overshoot on my DHW. This was limited by the mechanical thermostat on my cylinder closing the DHW valve but the CS92 took nearly an hour to transmit a temperature update and turn off the BDR91. I think if your CS92 is in the same county as any of your BDR91s you might be getting RF interference if your heating is back on again.

    I am now resigned to the CS92 being a dodgy bit of plastic and just hope that Honeywell might bring out a mains powered device before too long. I could try hanging the CS92 out of my bathroom window but I am losing the will to try with different orientations. I really don't think customers (or installers) should have to jump through such hoops with the placement and orientation of devices offered in the retail market, but I will just put up with its idiosyncracies for now. My mechanical thermostat protects me against very high temperatures so I will give in.

  4. #4
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    I have had this problem off and on over the past 2 years. I replaced the CS92 last year and had issues again in the Spring. I hope that I am not tempting fate but itís been fine for the past 6 months. Tech Support checked the old CS92 and said that there were no issues, and it was just one of those things! Thinking about it, any loss of comms would not have much effect on my HW heating as the ON period is an Evotouch setting, and the cylinder temperature would be controlled by the unvented cylinder stat which is set slightly higher that the Evotouch setting.

    Following a boiler change in April, I now only have one BDR in the airing cupboard with the Opentherm Bridge now located in my integral garage. It will be interesting to see if the problem returns.
    Last edited by HenGus; 5th October 2017 at 07:09 PM.

  5. #5
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    I had problems when I first installed my CS92 with random overshoots and the occasional comms error despite excellent signal readings every time I checked.

    The thing that made the most difference for me was retensioning the battery contacts behind the PCB, (by removing the PCB, bending them up a bit then refitting it) not where they go to the battery. I still had minor problems after that until I moved the location of the CS92. It then worked fairly well with almost no trouble for about 6 months and I started having problems with overshoots and comms errors yet again.

    I got it replaced under warranty about 3 months ago and touch wood I have not had a single overshoot since then. I have to say - of all the Evohome kit the CS92 seems by far the most fragile and unreliable.

  6. #6
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    I'm seriously considering hooking my CS92 up to a 3V mains adaptor!

    Something like this: https://www.amazon.co.uk/Battery-Eli.../dp/B01MAWHOPM

  7. #7
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    Quote Originally Posted by dty View Post
    I'm seriously considering hooking my CS92 up to a 3V mains adaptor!
    I don't see how that would help. The problem is that the CS92 firmware has been designed to conserve battery life and so only communicates with the controller when there is an R in the month or if Venus is in the ascendant. There are several threads that have discussed the logic inherent in the CS92, such as:

    http://www.automatedhome.co.uk/vbull...ll=1#post28631

    Whether you power the CS92 by battery or by a kryptonite power inverter, it would not change the operation of the CS92. We need one that was designed for permanent mains power and that communicates every minute.
    Last edited by Edinburgh2000; 6th October 2017 at 08:10 AM.

  8. #8
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    Quote Originally Posted by dty View Post
    I'm seriously considering hooking my CS92 up to a 3V mains adaptor!

    Something like this: https://www.amazon.co.uk/Battery-Eli.../dp/B01MAWHOPM
    Batteries running low is not the problem. Batteries seem to last a long time in these and just before I got my faulty (?) one replaced I checked the batteries and they were still both at 1.6v which is above spec for Alkaline. In fact I purposely transferred the exact same batteries into the new CS92 instead of using the supplied ones and I have had no problems with the new unit for 3 months - showing it was never the batteries at fault.

    It's hard to know exactly what the problem is but the fact that tensioning the battery contacts on the rear of the PCB almost eliminated any problems for 6 months suggests that either the device is extremely sensitive to battery voltage or the battery terminals or PCB pads suffer from oxidation problems. (Since a intermittent/oxidised contacts could cause voltage drop or intermittent voltage "brown outs" that reboot the unit)

    As has been pointed out - ripple or poor voltage regulation on a mains powered battery "emulator" may cause more problems than it solves, so I wouldn't recommend it.

    I think the overly aggressive battery saving algorithms (which try not to send temperature update transmissions unless its absolutely necessary, so send them very infrequently outside the differential range) also contribute to the problems with overshoot, which I've analysed in detail in another thread...
    Last edited by DBMandrake; 6th October 2017 at 09:10 AM.

  9. #9
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    Thanks for the replies so far, seems I am not alone in the CS92 just deciding to start being temperamental. I will certainly look at the connections to see if any cleaning or retensioning will help. Though I do know that a quick removal and reinsertion of the batteries instantly reconnects the CS92 to the controller.

    What I may try, which is very heath robinson, is passing the battery power through a normally closed relay. The relay would be a fibaro FGS212 so I can control the 3v power using a 240v relay. Then every 24 hours, specifically ten minutes before the hot water is to come on in a morning, the relay would cycle the 3v power to the CS92. A very heath robinson (and ridiculously expensive) way of removing and reinserting the battery on the CS92.

    Any issues with the plan?

  10. #10
    Automated Home Ninja Dan_Robinson's Avatar
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    Oooh.. Me likey.

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