Hayward H2501, pilot is lit, but burners will not turn on. Pressure in filter is at 15 PSI. Checked the connections and they are ok

SOURCE: Hayward H250 (millivolt) pilot won't stay lit

make sure the flame hits the thermo couple if so then replace it lows has them in the water heater section thermo couple gets hot makes millivolt signal then opens gas valve

SOURCE: hayward heater not staying lit

possibly poor pilot adjustment or insuficient mv output from thermopile

SOURCE: Hayward Comfortzone pool heater pilot will stay

check for continuity at all control and safety components,i.e. press switch,high limits,thermostat,on/off switch and flame roll out switch

SOURCE: hayward h250ed1 heater wont stay lit

Try cleaning your filter if dirty there will not be enough flow to llet heater fire. If filters clean you can try jumping the pressure switch.

SOURCE: Hayward 250 heater won't fire up

Check the control circuit, specifically the pressure switch, for continuity with an ohm meter....any reading over 2 ohms needs to be investigated