So, we opened the pool last weekend and decided to use it this weekend as the air temp hit close to 90 (water temp was about 70). I tried getting the heater to run. Everything was connected and the gas line valves had been opened the week prior. The heater went through its process of trying to light, with no success. I called the pool builder and they said to try it for about 30 minutes as their may still be air in the gas line. After a couple hours of the heater going through its cycles of attempting to light, it finally did. When it did, it made a fairly loud noise (sounded like a small explosion) as if there was a good amount of gas in the system. Today, I tried it again to head the spa, and it took 2 full cycles to finally light...again, the loud noise upon made the noise on several occasions. Is this noise normal upon lighting or should I have it checked out? The heater in question was installed in August of last year and is a Jandy (Laars) LX 400,000BTU.