I've noticed significant rust in the combustion chamber housing of our 2007 pool heater, particularly where it connects to the manifold. We've had the pool for three years, but this is the first time I've inspected the heater's interior. I managed to clean up the rust and temporarily fixed the leak with heat-resistant foil tape, and it's working for now - heats the water and everything works. However, it clearly needs permanent fix. Could this issue be caused by condensation, a leaking gasket, or perhaps the heat exchanger? Is it worthwhile to replace the combustion chamber, or am I better off just getting a new heater? Thanks for any advice!