As the post says the heater came with the house when we bought it. Natural gas. this year at startup it would heat for a few seconds then quit. Fault ignition control. Replaced the ignitor and flame sense rod. Had the gas manifold and orifice professionally cleaned. Still getting the same fault. Now it runs through the pre-start and then the click of the gas valve opens then puff of gas ignition and then nothing. What can i check next? I have continuity from the Fenmar to the flame sense tip.