Random heating of hot water

[gazza77]

Recently we've found that our boiler fires up to heat the water without it being set to. This can be either when the heating is on, or neither heating or water is set to time. This tends to happen when we run water from the tank when it's fallen to around 12c or lower.

I was under the impression that there was no "minimum" water temperature that would trigger the boiler to fire to heat it. Is that correct? If so, any ideas what's causing this?

[Richard]

evohome frost protects cylinders so will come on when tank temps go below 10 degrees C and reheat for a short duration.