Electramate 2000 hot water problem

Mike,
When I turn on a hot tap, the water runs hot for about two minutes then becomes cold. After a wait of a few minutes the same will happen again. The plate heat exchanger is hot to touch before the tap is turned on but cools down quickly with the tap on. The bottom bar of the LED display comes on shortly after turning on the hot tap and turns off again after a while with the tap off. The store temperature T1 is 80C. T2 is 30C. and T3 40C. when the hot tap has been off for some time. With the hot tap on T2 and T3 drop to 20C. The green LED's flash on wnen the boiler is first switched on but do not come on when the bars of the LED display are on. When the room thermostat turns on, the radiators remain cold. The return pipe from the plate heat exchanger does not heat up. The pump vibrates and runs hot but does not seem to be pumping hot water. The rotor is not jammed.

Can you please suggest what could be wrong? I have had the boiler for 7 years and experienced the relay fire problem which I was able to repair but this fault defeats me!

Regards, Neil

Hi Neil

Firstly check that the pressure is correct in the unit (approx 1 - 1.5bar) as air in the system/zero water pressure would cause this problem.
Try running hot water and monitoring the PHE return sensor (T2) and DHW sensor (T3) readings as it may be that one of them is breaking down when they become hot (watch out for the tempertaure readings jumping to either ERR or to readings that are not normal (eg 85deg).
There is no green light to indicate that the hot water pump is running, but check that it is turned to speed number 3. The control board alters voltage to the hot water pump to control its speed and therefore the hot water temperature, although this would not result in no heat to the radiators.

If the readings remain normal and the pressure is correct with no air in the unit, it sounds as though the problem could be due to a failing control board.

Hi
If you get the email, and you can be bothered please reply to let us know what the cause of the intermittant hot water was.
Thanks
Paul.