sitting looking at weather overnight temperature drops and thought - what is the equivalent to a frost thermostat protection on a wood burner boiler. Clearly its damped down over night or even let go out til next day but what stops any sudden drop in temperature affecting a place in any part of the CH cct i.e radiator in a colder than average room. All pipe lagging etc is up to standard but then new houses with combi boilers have frost protection so ......?.