Geronimo W. Christ Esq wrote:
wrote:

My room stat controls the pump only and the boiler is controlled by
it's own stat. If the boiler stat has shut off the boiler and the room
stat is calling for heat the pump continues to run.

So the pump stops allowing the boiler to heat really quickly and then
shut itself off ? That sounds very dodgy indeed. My boiler would
shutdown and require resetting if I were to do that.

Quite a common arrangement for older systems. When the heating demand
is satisfied the pump is switched off by the roomstat and the boiler
then continues to run until the water temperature in the boiler rises
high enough for the boiler stat to shut it off. Conversely if the
boiler water temperature reaches the boiler stat setting before the
heating load is satisfied the pump will continue to run although the
boiler has shut off. In fact some vintage heating systems have no
roomstat at all and the heating is controlled by the boiler stat alone.