i ve got sabre 24 boiler seem to be working ok with a ik up when ch on boiler come on and off but seem to be a bit to hot as the hot water flow get hot even not using the tap so hot to the point the pipe outside the boiler (which is pvc type)burst 3 time in the past 2 weeks i change the stat on the hot water pipe near the heat exchanger no change there are 2 stat on the left on the heat exchanger do you think that might be faulty??any help would be appreciate thanks.