Hot water BDR91 switches on every morning

[BillM]

For the last few weeks (January / Feb 2021) the BDR91 which controls the hot water valve in my simple S plan system has decided to switch itself on for about half an hour every morning, just after I get up and the heating has started to warm up the house. This is a new trick it has learned. The controller knows nothing about it and the schedule shouldn't start hot water until late afternoon. For the last two years this has worked perfectly. Have Honeywell pushed through a software update recently without confessing? Any other ideas? I've done the usual re-binding of BDR91, tank sensor etc. Also noticed that the regular (daily) 'Hot water tank sensor comms fail' error message seems to have stopped. I have changed nothing in the system nor do I have any new toys which could generate radio interference. It's not a big deal at the moment as the boiler is on regularly through the day, but I don't want the boiler firing up just to make hot water when the weather starts to warm up a bit. Any suggestions very welcome.

Further thoughts.... the above behaviour stopped and the system has gone back to normal operation, only making hot water when scheduled. The only obvious change is that the weather has become much warmer. When my system was behaving as above the outside temperature was well below freezing, for several weeks. As soon as the snow melted and the temperature rose to single positive figures the system started to operate as it has for the last couple of years. Is there some sort of frost protect in the Evohome software which runs the hot water system for a short period when the outside temperature gets below freezing?

[Richard]

For the last few weeks (January / Feb 2021) the BDR91 which controls the hot water valve in my simple S plan system has decided to switch itself on for about half an hour every morning, just after I get up and the heating has started to warm up the house. This is a new trick it has learned. The controller knows nothing about it and the schedule shouldn't start hot water until late afternoon. For the last two years this has worked perfectly. Have Honeywell pushed through a software update recently without confessing? Any other ideas? I've done the usual re-binding of BDR91, tank sensor etc. Also noticed that the regular (daily) 'Hot water tank sensor comms fail' error message seems to have stopped. I have changed nothing in the system nor do I have any new toys which could generate radio interference. It's not a big deal at the moment as the boiler is on regularly through the day, but I don't want the boiler firing up just to make hot water when the weather starts to warm up a bit. Any suggestions very welcome.

Further thoughts.... the above behaviour stopped and the system has gone back to normal operation, only making hot water when scheduled. The only obvious change is that the weather has become much warmer. When my system was behaving as above the outside temperature was well below freezing, for several weeks. As soon as the snow melted and the temperature rose to single positive figures the system started to operate as it has for the last couple of years. Is there some sort of frost protect in the Evohome software which runs the hot water system for a short period when the outside temperature gets below freezing?

There is a frost protection system built into evohome for both heating and hot water. If you have any problems, simply call Resideo on 0300 130 1299 and use option 3 to speak to the UK team.