My natural gas heating stove, its a wall unit, when it shuts its self off after it has come up to temp, puffs, or surges, like its getting a sudden burst of air or gas (if i manually shut it down it don't do it). any Ideas? I have already taken the gas lines apart and blown through them to get rid of water. I have blown out the ceramic tiles in the front and have blown the whole heater out which has not helped.
