Heater shuts off when pump speed is reduced on a variable-speed pump

Safety: Adjust pump speeds from the pump controller; no need to open the heater for basic checks.

• Check minimum flow: Refer to the SunHeater manual for the minimum required flow rate or pressure. Program the pump to run at or above this speed when heating.
• Clean filter: Backwash or clean the pool filter to reduce system resistance.
• Adjust pressure switch (if adjustable): Some Water Pressure Switches have an adjustment screw. Slightly lower the trip point so the heater stays on at lower flows, but never bypass the switch.
• Test different speeds: Find the lowest pump speed at which the heater runs reliably and use that as the heating speed.