Pulsacoil 2000 - long running difficulty

Hello,

A long saga...

I have a Pulsacoil 2000 - the hot water stopped working and I called in the plumber. The plumber replaced both immersion units (which were apparently scaled up ). After draining down, replacing them and refilling, the unit still didn't work. A problem with the pump was diagnosed, which had seized. Another drain down, repair with a new pump (Grundfos 15-50) and refill. The boiler still doesn't work properly.

The problem now is that the water is tepid warm, not hot. Surprisingly, the water is hotter from the bathtaps than from the shower, but it fluctuates in temperature from the taps from tepid to reasonably warm (and is consistently tepid from the shower). The header tank is also surprisingly quite warm (although not boiling hot or steaming, as others have posted) and I had not noticed it to get that warm before.

Hugely grateful for any insights as to what is the ongoing problem. I wonder if the flow is too fast past the heat exchanger for the water to get hot enough.. Obviously, this is now becoming expensive so keen to avoid more plumber time if possible.

Many thanks.

Unit needs to be hot.
On top of the unit there are 2 pipes.
Grab the fat one (22mm) if you can hold it then would not expect very hot water.

If it is very hot. Then you could have sensor problem (there are 2)
Also the new pump is it the Gledhill XB004 ?
As the normal 15 /50 is not the correct one.
Pump goes from 130 to 240 volts hence the XB004

F & E tanks do get warm

PHE could be scaled up

Mike