main medway automatic water not staying hot

[axident13]

hi i have a main medway automatic heater (gas) for our hot water it is working but the water is not staying hot for long i have tried turning down the water pressure but the heater hardly lights at all then. the heater is lighting fine and burning fine but the water is not hot for long i hsve the winter summer knob on winter but that makes no difference any suggestions we be of a great help.
Axident

[gucciman]

when the water goes cool is the burner still running at full strength or has it reduced or even gone out?

[axident13]

hi gucciman
it is running at full strengh it only goes down if you turn the water down by the tap the water gets a bit hotter when you do this but it then runs cooler again. also the pilot light is now going out on its own. could this be anything to do with the therma coil?

[gucciman]

very very strange one. the pilot going out could be due to the thermocouple but also the overheat stat, the pilot injector could be blocked up or the gas valve could be at fault.
im at a loss to think why the water should be cool if the burner is at full strength, i would need to examine it and test the burner pressure and the throughput of water.

if your in the birmingham area give me a shout if you want it looked at.

[Diane1954]

ours isn't a medway but it runs colder in winter than summer because the incoming water is colder i suppose.