Pentair MasterTemp 400 cycles on and off

Apr 29, 2014
6
Los Gatos, CA
Moved from here.
Hi everyone,

I have exactly the same problem (heater starts cycling on-off after water temperature reaches high 80s). Based on this and other threads (and the Pentair troubleshooting chart in the MasterTemp manual) I've replaced both the HLS sensor and the thermal regulator (also referred to here as the thermostat and the thermostatic by-pass). But the issue persists. Can anyone help?

Cheers
 
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