Our Swimming Pool Heater will not ignite

Is the system switch on? Is the thermostat up to temperature? Is the pump running with a clean filter less than or equal to 16 psi on pressure gauge? Is the gas valve in the on position? Is the pilot lit? Is the gas supply valve open? Are all plumbing and filter valves open? If a bypass is installed, is it properly adjusted Contact a qualified technician if you still cannot find the problem.
S.Merillat®