One shower in the morning... nothing in the evening..

I have a pulsacoil 2000 which is 5.5 years old. It has started to be tempramental. I used to be able to get about 3 showers out of it no problem, plus the boost if needed extra water. Now I can get one shower which is hot in the morning, the second shower is only luke warm, then its cold. If no one has a shower in the morning at all, and you try to have the first one in the evening, it is only luke warm even with the shower on its max temp setting.

last week i had an engineer who pondered over it for a long time, both the elements were hot round the metal rim which you can touch with your hand, so he said it couldn't be the elements not working, as they either work or don't work. So we decided to change the heat sensor. this has not really made any difference to the amount of hot water. He also changed i think its called the stat? in the bottom economy 7 element

This morning when the shower started running at 7.30am i felt all the pipes, coming from the machine, into the heat plate, then out to the taps, they were all hot, could only touch for a few second at a time. But the bottom of the metal casing of the store was cold at the bottom, next to the element ( despite the metal ring of the element being hot) and the top part of the store was warm.

is it possible an element doesn't heat fully? also why does it not keep the water warm in the store when we haven't run any of it ?

HELP !!!

You need a better engineer.
The heaters need testing, not feeling to see if hot.
The unit is well insulated so it would not be that hot. Like the inside .The part which was fitted was it a Gledhill rod stat?
5.5 years depending where you are it could be scale.
But it could be bottom heater, one or both sensors, pump PCB or pump.
Look on this site home page 2nd line down, see if anyone in your area.
Mike
MGC/H2O

Thanks Mike. I Looked on the page of engineers, but no joy, hence why I had to search on line for a local company who said they knew the model etc... I am near Heathrow.

The machine delivers hot water perfectly when I use the booster switch ( of course only about a third of the tank) does this make any difference to what may be going on when it is heating overnight? IE the sensors you mention or the pump? does it use the same ones when its on the top immersion only?

I'm trying to narrow down the problem, as I'm not sure how else to get it fixed, apart from changing each part you mention, and seeing what happens...... this could be rather expensive!!

when you say scale do you mean on the bottom heater element?

If all is working ok when using boost.
Then all it can be is the bottom heater and or rod stat.
So that is not too bad.
Scale as in the plate heat exchanger.
Down load the books for yours from Gledhill site.
Try going on Google and typing in Gledhill repairer heath row.
Mike
MGC/H2O

Thanks again.

The bottom heater needs the machine to be drained? is that right? how long should i expect this repair to take?

I guess there is no way of looking in the plate heat exchange to see if its scaled??