When external thermostat dial is turned all the way up, the spa temp peaks at 95 degrees. As soon as it hits that mark the light goes off and it stops heating. Is there a way to adjust the thermostat to get a higher temperature?
Pool & Spa - Hayward - Comfort Zone Electric Spa Heater 11kw
Answers & Comments
Is the unit outdoors in an environment exposed to temperatures significantly lower (40 degrees or more) below water temp? You could be having trouble with the water in the heater at the heaters temperature probe being 104 but the tub is lower because the heater can not keep up with heat loss. The only way to "fix" that would be to bypass the heaters thermostat by installing an external one somewhere closer to the main tub water; for example in the skimmer area.
If that is not the case and the unit is in a more protected area the likely problem would be the thermostat in the heater. The probe is failing and that is why the temp never gets to 104 even though the heater is shuting down.
In summary, it is either an issue with heater output capacity vs. environment or a malfunctioning thermostat.
There is no way to calibrate it. As the part fails it will no longer read accurately and replacing it is the only option. It is not a very expensive part and replacing it is not very difficult; just be sure to power down the breaker prior to removing the housing.