Ive got a cal spa with a Balboa spa pack "system 1100". Ive had no trouble until recently, sometimes it will run 2 minutes sometimes 2 hours and it will shut itself down and display an "oh" error code. It is not always overheating. Is this the temp sensor? And if so should I replace the sensor and the high limit at the same time? Any help would be greatly appreciated! Oh yeah I purchased the tub in 97 if that helps.
GoodDave

Dave, First thing to try is try running it without a filter, if the water slows down too much through the heater you can build up heat and OH. Is it ever getting too hot in the tub and when heating is the heater too hot to touch? If so you have an actual OH problem, bad sensor set, stuck relay or something like that. The sensors can be checked by using an Ohm meter, they both should read the same if in air. The Baloba temp sensor you need would probably be the one where the temp and high limit are on a 4 pin connection to the board and they are sold as a set.

I have taken out the filter to no avail, still overheats. And it does occasionally get way to hot in the tub. I havent checked the manifold yet. The sensor that is connected to the actual outside of the heater tube is a single sensor on a 4 pin hookup, which seems odd since all I can seem to locate are the ones you described. Maybe I was looking wrong. If I am wrong what ohms reading, in the air, should I get?
There was a 2 pin connection right below the 4 pin, not sure what it was??
Thanks for the quick response!
GoodDave

Well Dave, I won't have a ohm chart on the sensor till tomorrow. I will try to get back to to then, drop me an e-mail so I have it in my in box if you don't mind.

No problem, thanks for the help!
GoodDave