Thermostats turn off whilst scheduled to maintain 18degrees

[JeffG]

Whilst I have been extremely happy with my Evohome system controlling 16 rads in my home for two years, recently the two rads in one room have been turning off (to 5 degrees) whilst the system schedule shows they should be maintaining 18 degrees. No window or door has been opened!! Is there an obvious answer to why this may be happening?

[Mallo]

Whilst I have been extremely happy with my Evohome system controlling 16 rads in my home for two years, recently the two rads in one room have been turning off (to 5 degrees) whilst the system schedule shows they should be maintaining 18 degrees. No window or door has been opened!! Is there an obvious answer to why this may be happening?

Hi
Perhaps it maybe worth trying to re-bind the two rads???

[Siddy]

Hi
I had 2 heads do this to me on the 15th Dec and she hadn't moved them.

[IKnowNothing]

I had my lounge which has 2 rads and hence 2 heads change temperature to 23C from 20C on 17th November 2017 at 14:20 in the afternoon while I wasn’t there.
The schedule screen reported that it was caused by override, but there is only me in the house and there was no iPhone logo to indicate the cause. With these faults one tends to forget how things were found, so for the last few faults I have taken photos of the screen causing the problem, but unfortunately I did not take a photo of the multi room screen which would have showed if there was an apparent manual override.
From past experience I have removed it from the net for a while.....but more importantly for BT routers I have changed the SSID and admin passwords to something completely different with 12 characters each, upper case lower case and obscure symbols! No repeat experience yet.....but with Honeywell Evohome I have needed patience!

[IKnowNothing]

And again this morning I awake to find the lounge which has two rads still at 10c instead what the schedule says at 21c till 10am which then should drop to 20c.
The screen said there has been a manual override...this wasn’t me and because it happened overnight I am unsure when exActly.
Took photos of the relevant screens for later perusal and Reset the override so we are back to normal.
Obviously the change in BTHub5 SSID password and admin password has had not effect.
Trying to get a printout of the router event log to identify any suspicious entries.

[JeffG]

Thanks for the replies. Further investigation on the Honeywell website has led me to adjust the 'window open' sensitivity settings (setting 4) on each of the affected radiator controllers. So far the problem has not recurred.

The problems which had previously occurred were during very cold weather (eg. external temp <2 degrees C) and the radiators are sited under large windows, so I guess that air cooled by the cold windows was flowing down to the rads once they had achieved their set temperature and this must have triggered the 'window open' facility (which can also be turned off by re-adjusting the rad controller settings).

[Bart]

Try to disable local override for the troubled zone, just to see if it makes a difference.
But even so I had a strange experience where an older hr80 that got caught in an eternal reset loop would change the setpoint

@IKnowNothing

[DBMandrake]

I had my lounge which has 2 rads and hence 2 heads change temperature to 23C from 20C on 17th November 2017 at 14:20 in the afternoon while I wasn’t there.
The schedule screen reported that it was caused by override, but there is only me in the house and there was no iPhone logo to indicate the cause.

An unexpected override to 20 degrees is probably a spontaneous reboot of an HR92 in that zone due to either batteries that are getting low or a poor battery connection. With a low battery or poor battery connection the load from the motor turning can cause a momentary power "brown out" that triggers a reboot. I've actually seen this happen a few times while I have happened to be looking at an HR92.

When an HR92 is rebooted it defaults to 20 degrees - when it sends this 20 degree set point after rebooting the controller sees it as a manual override even though no human turned the dial...

The battery contacts of HR92's seem quite troublesome - the spring contacts at the bottom seem to lose their tension (or didn't have enough to begin with) resulting in intermittent connection after the weight of the batteries over time squashes the spring contact down further. I've had to bend and re-tension the bottom battery contacts on 5 of my 8 HR92's over the last two years due to them intermittently rebooting... This can be carefully done with a small flat blade screwdriver - only bend the middle part of each contact up about 2-3mm.

The way I check them is to remove the HR92 from the radiator, hold it upright in my right hand, hold my left palm out flat and then thump the bottom of the HR92 down against the open palm to give it a little jolt - if the battery contacts are loose you'll see it reboot as soon as it hits your palm... After re-tensioning the contacts the same thump should not reboot it.

I now check and re-adjust the battery contact tension whenever I replace the batteries.