Natural gas. ran last in December and valves are open.....if these are shut off, is there a specific sequence for opening the manual valves again? I have one by my meter and another by the heater.
I blasted all the dust with a compressed air line so there should be no obstructions. The pilot gas tube was clear - I just don't smell any gas.
the gas valve does 'clunk' on when the system calls for it to do so.
turned the gas off by the meter then back on again- same at the heater.
switched on the pool pump and heater and it fired up! weird eh?
the whole heater did wobble/judder a couple of times, never noticed that before.
will test it on my spa at the weekend.
I suggest you run your heater every few weeks. Don't go for more then a month without running it. The heater siting idle is not good for it. You will have less problems if you fire it up every week or two for 15 minutes or so.