Evotouch controller does not recover from power failure

[sharpener]

Yesterday I inadvertenly let the batteries on my (monochrome) controller go flat. After being put on charge it appeared to have recovered - in that the programmed times and temperatures are OK and it displays the actual room temperatures correctly. However the HR80 radiator valves no longer respond to it and during the night they all defaulted to 20C and the heating came on unexpectedly.

Some valves display the comms icon, some do not, it makes no difference. The Economy button on the controller reduces some zones by 3 degrees but does not change them all.

Is there a way to reset the system short of uninstalling and reinstalling all the components?

TIA for any help!

[SensibleHeatUK]

The radiator controllers expect to receive communications from the Evo Touch unit every 5 minutes or so, and when the "miss" several messages they go into a comms failure mode and operate at a default room setpoint of 20 degrees. They then do not test for comms again for around 24 hours, at which time if the Evo Touch is responding again they go back to fully automatic control. If you power cycle the radiator controllers (pop out the batteries and refit them) this forces the controller to resync with the Evo Touch strasight away and gets you back normal without needing to reset or rebind any of the controls.

[sharpener]

If you power cycle the radiator controllers (pop out the batteries and refit them) this forces the controller to resync with the Evo Touch straight away and gets you back normal without needing to reset or rebind any of the controls.

Thanks SensibleHeat, good advice (having had to replace some batteries at Christmas I should have thought of that).

Pity these kind of wrinkles are not documented in the instructions - and not known either to Honeywell Customer Support, who advised me to re-bind everything!

[Rameses]

The radiator controllers expect to receive communications from the Evo Touch unit every 5 minutes or so, and when the "miss" several messages they go into a comms failure mode and operate at a default room setpoint of 20 degrees. They then do not test for comms again for around 24 hours, at which time if the Evo Touch is responding again they go back to fully automatic control. If you power cycle the radiator controllers (pop out the batteries and refit them) this forces the controller to resync with the Evo Touch strasight away and gets you back normal without needing to reset or rebind any of the controls.

This is worth pointing out - if there is a power cut - then the boiler wont fire anyway. If the power comes back on - the controller will come on and will work to the schedule it has within its nvram. It is only when evohome sends a command for heat that the boiler will come on. Not that your valve was asking for heat. Your valves will only operate according to signal they gain from the main controller. So they cannot make a demand without going through evohome.

[davidaj]

The radiator controllers expect to receive communications from the Evo Touch unit every 5 minutes or so, and when the "miss" several messages they go into a comms failure mode and operate at a default room setpoint of 20 degrees. They then do not test for comms again for around 24 hours, at which time if the Evo Touch is responding again they go back to fully automatic control. If you power cycle the radiator controllers (pop out the batteries and refit them) this forces the controller to resync with the Evo Touch strasight away and gets you back normal without needing to reset or rebind any of the controls.

Hi SensibleHeat - did you deduce this info through observation, or from someone at Honeywell? This is very important behaviour that is undocumented, and I believe I have encountered such a scenario on one of my HR92s where it was not acting in accordance with the schedule (the room has two radiators and the other valve was behaving as expected). This sounds like it had gone into a dormant state for 24 hours as you describe. I got it to behave again by just removing it from the radiator and reattaching - I did not need to remove the batteries, as I think the act of unlocking/relocking the switch at the bottom of the valve is enough to force the resync.

Does the valve show anything on its display to indicate it has gone into this dormant state, as the display on mine looked exactly as it normally would, making the deduction of what had happened all the more difficult!

[SensibleHeatUK]

This was information from Honeywell and we have since observed the behaviour for ourselves on some installations where the power has been off for a while but the radiator controllers continue to operate as they are battery powered. On the older HR80s the little wireless icon disappears and the setpoint changes to 20 degrees while this state is active. I've not noticed on the HR92 how the display changes when this mode activates, maybe Rameses can confirm.

[sharpener]

This was information from Honeywell and we have since observed the behaviour for ourselves on some installations where the power has been off for a while but the radiator controllers continue to operate as they are battery powered.

Odd that when the controller does not get any response it doesn't report it as a comms failure (presumably when it comes back up it sends all the current setpoints to the actuators to reassert control of them). This would appear to be a design problem with the handshaking protocol, as it seems to do it OK for other kinds of fault e.g. RF path obstructed.

Honeywell describe what happens as binary progression, each time the HR80 cannot get a reply it doubles the time before it tries again. So after the controller has been dead for 2 hours it will be waiting for another two hours before the next try.

This fallback process can't save a lot of battery power (as most of that goes on driving the motor anyway) so it's not clear what its purpose is. At the very least it would as davidaj says be good if it was documented in the actuator literature, along with the suggested recovery process.

[top brake]

Quickest way to restore comms across the system is a power cycle on/off/on with all devices.

Leave the evohome controller in its dock while you do this.