Coldtub

How do I know which I need to replace or service? One person says it is definitely the sensor and the other says the cell.

What is the best way to clean these sensors?

The temp controls are set all the way to the hottest point, so yes, the heater shuts off after about 15 to 20 minutes. If I try to restart I can not get it to go again for a while.

Thank you - I really appreciate your advice. I just removed the brass fitting and made sure it was clear and it was. I just started the heater and again it shut off after about 15 minutes or so.

ok so I pulled out the flame sensor rod and used a little sand paper to clean off. Also checked the wire and the connections and they appear to be fine. Fired it up again and still have the same problem. the heater stays on for about 20 minutes or so and then shuts off well below desired temp.

Very interesting that we all have similiar issues at one time or another. Now mine is lighting fine, stays lit for a while, and then shuts off before the water gets warm. What do you suppose is going on here and what is the fix?