Help with water temperature problem please

[colin]

Hi,
Can anyone please assist with the following problem, it is to do with heating and OH signs appearing. An example is as follows:
Firstly, whenever I switch the Hot Tub on the temp. setting always reads 35c – it does not revert to the last set temp. when it was turned off.
This morning I turned the hot tub on and set it at 30c, on start-up it read 24c.
It got to 30c and kept on going. When it got to 32c it switched off and showed an OH sign. It definitely was not OH as I checked with a thermometer and it was 32c.
The filters are clean and I have tried leaving them out, also the gate valves are definitely open
I have had a new element fitted and new sensors fitted (I fitted one to the tub and one into the slot at the side of the element).
I was wondering now whether (a) to replace the flow pressure switch or (b) whether the pump is at fault or (c) do I need a new circuit board .
It is a Spaform Milano Hot Tub about 8/9 years old.
Thanks for your help.

[Chas]

Test the pressure switch. To do so, disconnect it and put a meter across it. Turn on the pump and see if it closes the circuit with pump running and opens the circuit when the pump shuts off.

The P switch is a mechanical device which turns on and off every single time the pump goes on an off, and as such is prone to failure.