I have a Cal Spa, With a balboa Instuments 2100 system. I get "OH" On the control temperature led. I shut down the spa wait a couple of days and then turn it on. set the temp at 100 deg. but it still over heats. the temp led after the first 4 hr filter cycle reads 105 to 106 deg. I have already replaced the temperature sensor / high limit sensor, ( they come together as 1 unit). I don't know of any other sensors that monitor temperature.
I am not sure if the only other solution would be to replace the circut board. The relay that contols the heater is soldered to the board, but it does not seem to be operating. Can this relay be checked without removing the board, and can it be replaced.

Any help would be greatly appreciated
Bobyt

"OH" is an Over Heat condition. Try running with out a filter to see what happens, then call me to discuss other things to check.

JEFFZ
Thanks for all your help up to now.
I finally got the time to check the spa again. The relay that operates the heater is working properly. I allowed the spa to cool down to 83 deg. When I turned the spa on it went into its 4 HR filter cycle. I turned down the temperature to 80 deg. The heat on light went out. Turned the thermastat control to 85 deg. relay moved and I could see an arc in the contact area.
I left the spa run with temperature set at 85 deg. checked 2 hrs later. temperature was at 87 deg. I tried to file the contacts on the relay but the space allowed there just wasn't enough, All I had was an emery board. I cut it down for proper width , but it was just too thick. could the board be shorted to allow the heater to remain on even when the relay is turned off?
Still at a loss.
Please any other suggestions would be apreciated.
Bobyt

Would it be possible the spa isn't heating from the element, but extended filtering cycles while the spa is already at the set temp? A pump running for several hours has the potential to heat (albeit gradually) the spa water. When ambient temp is as high as it has been in many parts of the country latley, this can lead to a slow, gradual increase in water temp.

Try venting the cover in the evenings to determine if you're looking at an equip problem, or an ambient temp issue.

Good luck