the water temperature is look warm , throttle fully open water pressure fine , just can't seem to get the water temp up.boiler fires up fine ,initial temp red hot but quickly cools
symptoms suggest the 'diaphram' is punctured. The flow of water against this rubber disc pushes open the gas valve. However after several years of operation it perishes and starts to leak. Needs a gas fitter to replace. Should take 1 1/2 hours.
