Water flow issue with heater that throws a high limit switch (HLS) error code

[Mastalx]

I have a Pentair starite max e therm pool heater. The heater turns on and then turns off then turns back on. It takes 3 hours to heat a spa to 101 and I am a new pool owner, had no clue that the heater wasn’t properly working and I am probably just wasting a lot of gas with it going on and off.

I am trying to diagnose this step by step. I already changed the HLS switch with a new one. Then I switched the values between pool and spa.. noticed the error doesn’t appear for both, only the spa. So heater works fine when it’s set for the pool. I have Jandy electric valves and not sure if that’s broken. The filter was 25 psi when valves were turned for pool and then 30 psi when valves turned for spa.

I have narrow the problem down to it being a water flow issues. The heater works fine on pool; it doesn’t turn off and no error code. The minute I switch the valves to spa then within 2 minutes the error shows.

I am skeptical that backwashing and cleaning the filter will fix this because the heater works when valves are set to the pool. My only guess is that valves could be broken.

 

[ajw22]

Backwash and clean your filter. PSI of 25-30 is too high for most filters. Report what the clean filter pressure is.

There is nothing wrong with your valves.

Your spa jets have more “head” and back pressure that result in less flow than your pool. Your heater has enough flow from the pool and not enough from the spa.

What model pump and filter do you have?

Check the thermal regulator and the bypass valve. They can effect the heater internal water flow.

The Starite heater is internally the same as the MasterTemp…

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[1poolman1]

I have a Pentair starite max e therm pool heater. The heater turns on and then turns off then turns back on. It takes 3 hours to heat a spa to 101 and I am a new pool owner, had no clue that the heater wasn’t properly working and I am probably just wasting a lot of gas with it going on and off.

I am trying to diagnose this step by step. I already changed the HLS switch with a new one. Then I switched the values between pool and spa.. noticed the error doesn’t appear for both, only the spa. So heater works fine when it’s set for the pool. I have Jandy electric valves and not sure if that’s broken. The filter was 25 psi when valves were turned for pool and then 30 psi when valves turned for spa.

I have narrow the problem down to it being a water flow issues. The heater works fine on pool; it doesn’t turn off and no error code. The minute I switch the valves to spa then within 2 minutes the error shows.

I am skeptical that backwashing and cleaning the filter will fix this because the heater works when valves are set to the pool. My only guess is that valves could be broken.

For years, when they existed, the first thing taught at any manufacturer's heater schools would be that, "Ninety percent of all service calls on pool heaters will turn out to show nothing wrong with the heater. Waterflow is the first thing to look at when a heater doesn't work properly." So far that has proved to be true.

You change the valves, you change the total head on the system. With a filter that is at the edge of needing a cleaning, the added restriction of the spa plumbing can be just enough to cause the issue you are experiencing.