During the pool build, the plumbers plumbed the heater incorrectly. We've been feeding water from the filter through the outlet of the (unused) heater for 3 weeks. They finally came and fixed it, now the pressure reads 10# lower. Should I be concerned about the heater and the effects this might have had on the internals of the heater? It seems to heat the pool fine now, but I did begin to hear rattling from the heater 2 weeks into it.