Leave last valve open until boiler stop commanded to avoid overpressure
When all valves close and stop asking for heat, it can take up to a minute for the room thermostat to communicate with the boiler to turn it off. In my house, as all radiators have tado valves, this leads to a very noisy banging sound as the pump tries to push water around the circuit when every radiator is closed. In a manual system, plumbers leave at least one radiator in the circuit without a TRV to mitigate for this problem, but this seems silly and (should be) unnecessary for a smart solution.
When the final radiator associated with a smart thermostat stops requesting heat, either:
- communicate the stop request, but leave the valve open for at least 2 minutes to allow the boiler to stop; or
- communicate the stop request and leave the valve open (also saving battery!). Close the value if necessary when the circuit is next activated and the boiler restarts.
I have had to remove a tado thermostat from one of my radiators and effectively have no control in that room. due to this issue. I have two separate pumping circuits in my house; so that's a loss of two device sales I would otherwise have purchased.