pulsacoil 2000 wont heat my water

Hi my friend has a pulsacoil 2000 which has been on the blink for sometime now, starting with what seemed as sensor failures so we changed then both.

Then we found the pump was faulty so we changed that & the compression fittings above & below it.

Now the red light flashes to say its working ok, 2 then nothing then 2 etc. There is power to both immersion heaters & both seem to be working & the heat exchanger heats up.

It still only heats up the water to barely warm.

Does anyone have any idea's as its driving us mad now !!!

Hi sliceofcake77,

Sounds like scale in the heat exchanger to me but can't be sure without answers to a load of questions:

1) Did this problem start suddenly or did the hot water get cooler over a matter of weeks?

2) Is the pump actually running when the hot tap is running cool?

3) If YES to 2), what is the voltage at the pump terminals when the pump is running?

4) Is the water level in the header tank correct?

Cheers, Mike

Sounds like calcium build up on the PHE circulation side. Confirm the pump is spinning and you installed a grundfos 15-50x18