Pulsacoil 2000 hot water for only 5 minutes

Hi we have done a repair on a Pulsacoil 2000 with a 170L Tank, we have changed both immersions and both heat Sensors but this hasn't fixed the problem. The water is getting hot (upto 70 degrees) but as soon as the shower is turned on with in 2-3 minutes the water temp drops to around 40-50. The circuit board seems to be working fine. Basically everything seems to working as it should but the performance is very poor. Please can you help with any ideas that we can do to fix this. Many thanks in advance for your replies

DHW on a 2000 will be approx 52c
Is it just the shower?
If so check filters or the thermostatic cartridge may be locking out when it gets hot.
Could be PHE scaled up and you would get hot water for a few minutes as it would be hot as standing in the PHE.
Could also be the pump and or Pump drive PCB
Are the hot taps doing the the same?
Mike
MGC/H2O
Norfolk

Cheers Mike,

The problem is in all taps, the tennant has said he is unable to fill a bath or have a proper shower.
The main store temp is 70deg. i dont think the PHE is blocked because the water reaches temperature and gets really hot. The PCB has been tested and is working fine and we have removed the sensor connector block to test the pump, this makes the pump pulse.
Im a little in that dark as to what else could be causing the water to be used so quickly?

Rob

When the water goes cold is the unit still 70?

No, it drops down very quickly to 40-50 degrees

Is the unit full?

Hi, thanks for responding, The header Tank is more than half full and the unit is also full. please help!!!!

The PHE could be blocked.
Only way is to take it off and blow through the DHW part
And the store part.
Turn water on and stick finger in pump, although you can stop it quite easily.
The hot water will only be 52c at any time.
When the hot water runs cold
Is the store still hot?
Feel the pipes on the PHE the back / rear ones.
If not ring me on 07885733007 and I will try to help you.
The PC 2000 is an easy Gledhill unit.
Mike