Hope you can help (again)
I have a United Spa main control box 6-7 years old. Model S3C-22-TL

When I set the timer for circulation and turn the temperature up on the main control panel the heat light in the main box comes on and everything's working.

If the temperature hasn't been reached by the time the timer switches the circulation off, the heat button on the main box remains on, continuing to heat the water left in the tube until the high pressure switch kicks in (15-20secs later) and turns the heating element off. I believe that, when the circulation is stopped by the timer, the heater should be automatically switching off too but this isn't the case. It could be that the relay in the main box is wired wrong but unfortunately I cant find a wiring diagram for the box and United Spas have been taken over (techs in new company unable to assist)

Any help would be appreciated.

Assuming it's not miswired, check for proper pressure switch operation.

Thanks Swine
I can hear the pressure switch click when I turn both clockwise and anti clockwise - where should I be leaving it - less or more pressure and will this then automatically turn the heat off when the timer stops
Al

Meter it out. It should be O/L with no pressure (jets off), and continuity when there is pressure (jets on, either low or high speed).