Question about Hayward H350FDN Low NOx Natural Gas Pool or Spa Heater

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Hayward pool heater will fire up but wont heat the water

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FEw thing there:

  • The thermostat may be set too low
  • Inadequate gas supply
  • Malfunctioning thermostat
  • You are losing heat faster then you are adding it. (If the heat loss in the pool is greater than the heat input, the heater might be too small or you may need a thermal barrier). Use a thermal barrier to help prevent heat loss
Keep that the heater should resume heating automatically if the timer turned off the system. If it is on a timer, you want to make sure the timer's microswitch (fireman's switch) is hooked up to the heater, to stop the heater about 10 minutes before the timer turns off power to the pump.

Also, I suggest check the H350FDN Owner's Manual and H350FDN Service Manual for other details.

Good luck.

Posted on May 28, 2010


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