On 23/11/2019 14:18, Andrew wrote:
Assuming a heat-only sysem with boiler, pump and
radiators (emitters!!), apart from a thermostat
what controls would be needed other than a timer ?.

I assume that a programmable stat would do the timing
and temp control, so no need for a wiring centre.

Would the boiler provide the power for the pump or
is a relay required ?.

Pump operated from the boiler will allow for timed overrun. Pump in
parallel with the boiler power connections from a 'stat switching mains
will just not have an overrun facility. System boilers have the pump and
an expansion vessel built in.

SteveW