Heater runs but then shuts off when pump speed is reduced (on variable-speed pump systems).

Safety first: Turn off power before adjusting internal switches.

Steps to stabilize operation with VS pumps:

• Increase pump speed: Program a higher speed during heater operation to maintain sufficient flow.
• Adjust bypass: If a manual bypass is installed, partially close it to direct more flow through the heater while staying within Raypak’s flow limits.
• Clean filter: Backwash or clean the filter to reduce system head and improve flow.
• Adjust pressure switch (if allowed): Carefully adjust the Raypak water pressure switch per the manual so it closes reliably at the chosen pump speed.

Note: Do not set pump speed so low that heater safeties are marginal; maintain a comfortable margin above the minimum flow.