Heater runs but pool water does not heat up or heats very slowly, with no error code displayed.

Safety first: Turn off gas and power before adjusting internal components. Do not exceed rated temperature or pressure limits.

• Check temperature rise: Measure water temperature at heater inlet and outlet with the heater running. A very low temperature rise suggests too much flow or poor heat transfer.
• Adjust bypass: If an external bypass is installed, partially close it to direct more flow through the heater while maintaining adequate system flow. Follow Aquacomfort’s recommended bypass settings.
• Verify run time: Ensure the heater is allowed to run long enough; large pools can take many hours to heat.
• Inspect for scale: If the heater is older or used with hard water, the heat exchanger may be scaled. Have a professional perform a chemical descaling.
• Gas supply check: If burners appear weak or noisy, have a licensed gas technician verify manifold pressure and supply sizing.