Pump start time after zone valve opens

[0ldskoolskater]

Hi,

When a zone valve opens and the aux switch calls for the pump to start, is there a delay after which the pump starts circulating or should it start immediately?

thanks

 

[Johntheo5]

If the auxy switch is a switched live to the boiler and the boiler PCB signals the pump to start there may be a delay but generally wouldn't expect a delay. If the auxy switch goes directly to the pump and to a heat only boiler then it should start immediately

 

[0ldskoolskater]

Perfect, thanks.

 

[stem]

There is a short delay from the thermostat switching 'on' whilst the motorised valve's motor winds it open and its mechanism reaches and operates the internal microswitch. However, it will only be a few seconds, probably 5 to 10 at the most.