I bought my first house this spring, along with it came my first pool and spa (both in-ground).
To make a long story short, I'm having trouble with my Pentair MasterTemp 400 heater. Originally when we bought the house the spa seemed to work fine (from my limited knowledge of spas).
In the last 2-3 months or so the spa heater has been cycling on and off. The Heater itself remains on, but it cycles off the heating unit, so it is blowing cold water thru the jets, then the heater turns on again and pushes hot again. Obviously this makes the spa take a very long time to heat up, and unpleasant when the cold water is blowing.
After some research, I bought and installed a new Thermal Regulator.
Amazon.com : Pentair 77707-0010 Thermal Regulator Replacement Kit Pool and Spa Heater : Portable Outdoor Heating : Patio, Lawn Garden
And it seems to have helped. The off cycles of the heating unit in the Heater are shorter, about 30sec-1min. But they still happen.
What would my next step be in trouble shooting this?
(The original Thermal Regulator was very corroded. I have no idea how long it had been in use, but it had a thick patina of green oxidation on it.)