Problems with Hayward 100,000 Btu Heater

The exhaust fan has rusted out. Remove it and replace with a new one. The heater will not ignite it it doesn't sense a vacuum created by the fan.

It sounds like the thermostat is turning the heater off before it gets the water to temperature. It is probably the sensor, as that is the most common cause, but may be otherwise.

AO will apply to your blower, blower tubing, or blower vacuum switch. You need to check these items.

The igniter is most likely bad.Make sure the igniter is not working,and the pump for the fuel is working,one,or the other is not working,if it is the fuel,order a new pump kit,with impelar,and if it is the igniter,replace it with a new one.

If the fan comes on it has to be the ignitor or the ignition module

since heater is calling for heat,i suspect ignitor is faulty.it could just be dirty.remove it clean with fine steel wool.

check pressure switch,if it is faulty or out of adjustment it wont allow it to go tomain burner

Air pressure sensor on the blower blocked or damaged and not reading the fan is on. Control board not sending spark down to the ignitor. Check the short grey tube off the blower first. If clearing it works, great. If not, you'll likely need a warranty service call. http://www.haywardnet.com/locator/

You might have the blower wired incorrectly or a bad blower. Also make sure the hose is connected to the blower and pressure switch.