New to group/ heater issues

[Edsjet]

Hello all,
New to the group. We built a 17k gunnite salt pool 3 years ago here east of Dallas TX.
The pool survived snowmaggeden with a lot of effort, but now after about 10 heater uses this fall we’re starting to have heater issues. The heater heats the spa up to 100 f just fine but then cycles on and off- will only heat for about a minute at a time. Previously it would heat for about 5(ish) minutes before cycling off.
It’s a Pentair Mastertemp 400.
If it’s a limit switch or thermostat- is it diy or do I need a pro?

 

[ajw22]

Welcome to TFP.

Is your MasterTemp controlled by automation? An EasyTouch or IntelliCenter?

When you say the heater heats the spa to 100F then short cycles where are you measuring the 100F? What does the temperature on the MasterTemp display show?

What model pump and filter do you have?

Please create your signature with details of your pool and equipment. It helps us help you and keeps folks from asking you about it repetitively.

The short cycling could be caused by low water flow. When was the last time you cleaned your filter? What is your filter PSI?

It could also be a problem with the thermal regulator or bypass valve in the heater.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com