More items on the way.

I purchased a55 gallon storage tank and brazed plate heat exchanger.  After much investigation, an open system in my location will not be legal or economically feasible.  I am proceeding with a water/glycol closed system and using a wort chiller heat exchanger to preheat the water before it enters my electric water heater.  Calculations show that if I can heat the 50 gallons of water/glycol to 140F and pump with a sufficient flow, I can get about 15 minutes of flow out of my water heater before the thermostat kicks on at 110F.  This method, although not as efficient, removes all the issues relating to freeze protection and backflow prevention. Parts were $100 for the exchanger and $180 for the tank (uninsulated)