Heater runs but pool water does not reach the set temperature or heats very slowly.

Safety first: Turn off power and gas before opening panels. Do not attempt gas pressure adjustments unless licensed.

• Verify expectations: Check that the Nirvana heater BTU rating is appropriate for your pool size and climate. Large pools may require many hours to heat.
• Check gas supply: Ensure the gas line size and meter capacity meet Nirvana specifications. Other appliances running simultaneously can reduce available pressure.
• Inspect burner flame: With a professional present, observe burner flames through the sight glass. Flames should be stable and mostly blue. Yellow, lazy flames can indicate poor combustion or low pressure.
• Descale heat exchanger: If the heater is older or used with hard water, internal scale can reduce heat transfer. A technician can chemically descale the Nirvana heat exchanger.
• Reduce heat loss: Use a pool cover when heating, shield the pool from wind where possible, and verify that the heater is not short-cycling due to incorrect thermostat placement.