I have a sundance spa that is about 10 years old. I am getting an OH code and it reads for a temp about 109 but the hot tub water is cooling down. Water can I do to remedy this problem.

Thanks is advance for any help
Dave

You need to determine first if the heater cannister is getting hot... We're talking about the actual heater, not the water in the tub.

Thank you I will check that after work today.
I looked at the tub this morning and there was steam coming out when I lifted the cover but the water was luke warm. The temp read 105. Then the tub kicked on and when that happened the OH error came on and read 111. I'd say the temp is around 80.

Thanks again for my first course of action.

Dave

I checked my heater and it seems to be about the same temperature as the water in the tub. I put another thermoter in the tub and it reads about 80 degrees. The tub will not get any hotter. I started with an OH problem but that error seems to have gone away after I shut the breaker and turned it back on. The reading on the panel still says 103 but the water is not that temp. I removed the filter cartridge to help the flow of water through the system. This may have gotten rid of the error. I'm not sure.
What would be my next step in diagnosing this problem? The water is not freezing which is good. I just notice I have a slight leak just after the flow switch. Would this be part of my problem?

I just remembered that I did notice that when I up the temp on the control panel to 104 the flow light turned on and the heater light turned on but the actual temp didn't seem to rise.

Thanks again for any and all help
Dave