The controller is fine - no issues with any other devices. The CS92A is just poorly implemented IMO.
My original one was far worse, the replacement one has been a lot better, (but not problem free) this might suggest a quality control issue (particularly with the battery contacts, same with all other Evohome devices) but I've also identified some basic design flaws with the way the device decides to send updates that can lead to overshoots in certain circumstances. Well documented in another thread so I won't repeat all the details here.
If it works for some or even most people then great, however that doesn't mean it doesn't have design flaws that affect some people.
There's only so many times "interference" etc can be blaimed for comms issues before we just accept that the wireless comms protocol used by Evohome has shortcomings, and that the CS92A in particular takes battery saving to the extreme at the expense of causing comms failures. (By not sending updates when it really ought to - over 3 hours without the controller receiving any updates from the CS92A while the rest of the system works perfectly is not "interference")
Overall I like Evohome but I couldn't recommend the hot water control side of it as the entire control loop from sensor to controller back to BDR91 relay is just too "fragile". I really don't like that control loop having two wireless communication links involved.
A better way to do it would have been to combine the temperature sensor with the relay so that the Evohome tells the combined device what the hot water set point and differential are, and the temperature sensor directly controls the relay without any wireless comms, then sends the temperature reading back to Evohome for it to control the boiler relay and for informational purposes. In such a design overshoot due to comms issues would not be possible. The boiler might run on a bit longer but the hot water relay would always close at the correct time even if wireless comms were lost avoiding scalding hot water.
My original one was far worse, the replacement one has been a lot better, (but not problem free) this might suggest a quality control issue (particularly with the battery contacts, same with all other Evohome devices) but I've also identified some basic design flaws with the way the device decides to send updates that can lead to overshoots in certain circumstances. Well documented in another thread so I won't repeat all the details here.
If it works for some or even most people then great, however that doesn't mean it doesn't have design flaws that affect some people.
There's only so many times "interference" etc can be blaimed for comms issues before we just accept that the wireless comms protocol used by Evohome has shortcomings, and that the CS92A in particular takes battery saving to the extreme at the expense of causing comms failures. (By not sending updates when it really ought to - over 3 hours without the controller receiving any updates from the CS92A while the rest of the system works perfectly is not "interference")
Overall I like Evohome but I couldn't recommend the hot water control side of it as the entire control loop from sensor to controller back to BDR91 relay is just too "fragile". I really don't like that control loop having two wireless communication links involved.
A better way to do it would have been to combine the temperature sensor with the relay so that the Evohome tells the combined device what the hot water set point and differential are, and the temperature sensor directly controls the relay without any wireless comms, then sends the temperature reading back to Evohome for it to control the boiler relay and for informational purposes. In such a design overshoot due to comms issues would not be possible. The boiler might run on a bit longer but the hot water relay would always close at the correct time even if wireless comms were lost avoiding scalding hot water.
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