I have a year old raypak 106a natural gas heating unit and since first use it has blown the ceramic rollout/hi limit switch 3 times. The btu inlet is spot on at 106,000 btus. I have taken off the top to look for any blockage also the water pressure appears to be good also I have backed down the gas pressure to an inlet of 90,000 btus by clocking my gas meter and still no relief. I have spoken with a raypak rep here in NJ and was told raypak had an issue with the spring in their header. Has anybody heard of this and is there anything else I might be missing......thanks