Recommended temperature difference between boiler shutting down and re starting?

[gemius]

Hi.
When my boiler reaches the set temperature and shuts down how many degrees would you expect the temperature to fall before it re-starts and is this difference adjustable.

 

[Johntheo5]

Gas fired boilers do not shut down at the setpoint temperature but the burner shuts down at the SP+5C, otherwise they couldnt modulate, the burner will then refire after a settable anticycle time of ~ 5/10 mins, in which time the temperature should fall by up to 15/20C.
If all heating demand is finished the burner will shut down irrespective of the flow temperature but the circ pump will run on, pump overrun, for another sometimes settable time of maybe 3 mins.
Oil fired boilers which do not modulate but cycle continuously do shut down at the SP and refire at ~ SP-8/10C.

 

[Rodders53]

It all depends on the boiler make and model, surely?

Fairly sure that some boilers will not do what has been described above as they simply don't have the features described (e.g. pump overrun has never been a feature of the boilers I have owned in my lifetime).

 

[vulcancontinental]

Hi.
When my boiler reaches the set temperature and shuts down how many degrees would you expect the temperature to fall before it re-starts and is this difference adjustable.

That would depend on the hysteresis above and below the setpoint and duration of the anti-cycle delay if there is one. Better boilers allow adjustment of all three to suit an installation if the installer can be bothered.