My (old) Potterton boiler has an off delay for the pump. When the MTV switch lives click off a permanent live allows the pump to continue for a short while to dissipate excess heat.
But what I don't get is this;
What is the point of running the pump if both MTVs are closed, effectively isolating the boiler? Presumably they stop the water flow anyway?
The boiler has an additionalcut out and I am having to reset it from time to time. I'm guessing that if the timer switches the valves shut while the boiler is firing then the boiler overheats and the cut out operates. Next time the timer calls for heat the boiler doesn't respond and has to be manually reset. Bit of a nuisance on cold mornings.
But what I don't get is this;
What is the point of running the pump if both MTVs are closed, effectively isolating the boiler? Presumably they stop the water flow anyway?
The boiler has an additionalcut out and I am having to reset it from time to time. I'm guessing that if the timer switches the valves shut while the boiler is firing then the boiler overheats and the cut out operates. Next time the timer calls for heat the boiler doesn't respond and has to be manually reset. Bit of a nuisance on cold mornings.