solar water heater tank...

[Nate Nagel]

Hi all,

I've posted before about this. I have an indirect solar water heater in my basement, it appears to be basically a Rheem electric water heater fitted with a coil of copper tubing around the tank which has an antifreeze fluid circulated through it by means of an electric pump. It's toast. It's 20 years old, rusty, and leaking. I've searched online and it appears that the only product currently available is one single model of tank (from various suppliers) which runs about $1000.

Question: Could I simply purchase a new electric tank of approximately the same size, disassemble it, reuse the existing copper coil, and reassemble? There appears to be no issues with the antifreeze/heat exchange fluid piping, but the water tank itself is done for. I realize that if I were to do this that there would be no warranty, but for the $700 plus price difference, I could live with that.

Does this seem feasible, and has anyone done this before?

thanks,

nate

[hallerb]

how will you get the copper coil inside the tank?

[Nate Nagel]

As I understand it, it's not actually inside the tank, but wrapped around the tank but inside the outer sheetmetal shell in a long spiral. Of course, I can't state this with 100% certainty as I haven't removed it and cut it apart yet.

As an aside, but a related one - how does one "charge" the heat transfer fluid? It appears to be pressurized to about 20 PSI.

nate

[mm]

If it's in the basement, it must really be indirect.

I tried having a hydrogen fusion reaction in my basement, and it made even my first floor too hot to live in.

A standard water heater, with 2 inches of insulation between the tank and the outside, where the copper coil is? If that's it, I would think it heats the basement a lot mor than the water.

Could you post a url for that, so we have a better idea of what you are talking about?

In what way are you going to disassemble it? Take off the top and slide the coils down where the insulation is now? Maybe, although you wouldn't have much insulation then for that part of the tank.

[mm]

Is that because the pump is running?

Other than that, I think there is no way to pressurize antifreeze (which would only expand a tiny bit), but if you make everything real hot, you can pressurize the air in the tubing, like in a car's cooling system. I don't see any advantage to it being pressurized since I don't think it reaches the boiling point. The purpose of pressuring the car's cooling system is to raise the boiling point. At any rate, if it's sealed, the pressure will increase as the temp goes up.

[Nate Nagel]

There's a small expansion tank teed off one of the lines, and there is a pressure gauge showing 20 psi on it at all times, pump running or no.

to reply to your other post, here's pretty much what I have:

nate

[gfretwell]

If the collectors are 2 stories up plus the rafters that is about right for gravity alone

[Nate Nagel]

Nope, collector is cantilevered off of the deck. It used to be on the roof but the PO decided not to put it back up there when he had a metal roof installed.

nate

[Eigenvector]

Pressure gauge might simply be wrong - they don't last forever. Have you tried the old tapping on the guage faceplate trick to see if it changes?