I have a wood furnace with a domestic water coil which circulates through a 80 gallon preheat water tank. When hot water is drawn through the house the preheat tank feeds into the main hot water heater. My problem is that my circulator pump circulates from the bottom of the preheat tank through Wood furnace then back to top of water heater. Problem is that when I am using a lot of hot water the cold water gets circulated from bottom to top and goes directly to house water heater, not getting the true hot water in tank, more of a cold mix. I'm thinking of reversing flow of water circulator. What r ur thoughts?