Overheating Marquis Spa

[sj22182]

I have a very old Marquis spa that is still working well. For the past couple of months, the spa has been overheating and tripping the hi limit switch. I came out last night and the spa was at 120 degrees! I am sure I need to replace a temperature switch or something and I am wondering where it is and which replacement switch I need to order. I was also wondering if the hi limit switch could be turned down so it would trip at 106 degrees.

1) The Spa has a main label in the equipment area, the label has a model number 41K8 Spa and the Serial Number is SB- HI-Y-069203. I understand that this model may be 20 years old.


2) The "box", which houses the electrical components, also has its own label, "Simplicity" Model 18B3700, Cat No 101631110, Serial No 89041314 -


3) The pump is a Flomaster, this was replaced along with the heating element 2 years ago.

4) The relay is a Picker Components PC-25-4
NO: 25A 240 vac
NC: 15A 240vac
COIL - 120vac

[hottub.pool_boy]

Yes, it sounds as if you have a run-away thermistat. It's behind the knob you're turning up and down.
No you can not field adjust a high limit.
Replace the thermistat. Match to length of the capilary tube(brass tubing very small dia.). Match the bulb length and width. Start there.