Our water heaters are installed! Yes, that’s plural, as in two. The little (50 gal.) tank on the left is actually a pre-heat tank that doesn’t even power on, but it ties in directly with our geothermal system’s hot water generator feature. This is a function that allows a separate heat exchanger inside the geothermal furnace to heat water at a much lower cost. It then sends it into the pre-heat storage tank, which then feeds into the larger (85 gal.) Rheem Marathon water heater. The ClimateMaster rep said it would save somewhere in the neighborhood of $150-$200 per year on our water heating costs.