Jim Moss
New Member
I have a 1970's drainback system for my active solar house. Part of the system is to preheat water that is going into our electric water heater. This preheat system has a failed exchange coil.
Let me paint a picture for you: I have a large tank in the cellar that holds 2500 gallons of hot water (generated from the house solar system). Inside the tank, there is a copper coil. This coil is connected to our well on one side and to a mixing valve going to our hot water heater on the other side. The copper coil takes heat from the tank and heats the cold water from the well prior to it being heated by the electric tank. In some cases,the electric heaters never come on because the pre-heated water is so hot. After 40 years of serrvice, the copper coil has finally corroded t the point that it is no longer functioning.
Instead of replacing the coil in the tank (which would be very complicated), I thought an outside the tank heat exchanger tank would be a good solution: run a pipe from the 2500 gallon tank to a small circulating pump and then into the heat exchanger tank and then return it to the 2500 gallon tank. The heat exchanger coil in the external tank would be fed by the well water and go to the mixing valve. I could imagine the external tank holding 100 gallons of recirculating solar heated water.
So, where to get a tank like this............
So, where to get a small energy efficient circulating pump?
So, should it be a single wall or double wall tank (and if double wall, then transfer of heat is seriously diminished).
Got any ideas?????
Let me paint a picture for you: I have a large tank in the cellar that holds 2500 gallons of hot water (generated from the house solar system). Inside the tank, there is a copper coil. This coil is connected to our well on one side and to a mixing valve going to our hot water heater on the other side. The copper coil takes heat from the tank and heats the cold water from the well prior to it being heated by the electric tank. In some cases,the electric heaters never come on because the pre-heated water is so hot. After 40 years of serrvice, the copper coil has finally corroded t the point that it is no longer functioning.
Instead of replacing the coil in the tank (which would be very complicated), I thought an outside the tank heat exchanger tank would be a good solution: run a pipe from the 2500 gallon tank to a small circulating pump and then into the heat exchanger tank and then return it to the 2500 gallon tank. The heat exchanger coil in the external tank would be fed by the well water and go to the mixing valve. I could imagine the external tank holding 100 gallons of recirculating solar heated water.
So, where to get a tank like this............
So, where to get a small energy efficient circulating pump?
So, should it be a single wall or double wall tank (and if double wall, then transfer of heat is seriously diminished).
Got any ideas?????
