attic solar water heater idea
 

Hello everyone,
This is my first post.
I have a row home in Philadelphia with a black asphalt roof. It has an almost flat roof--just a slight slope for water drainage. I pulled down the second floor ceilings and am installing R38 batts of insulation.
Before I do that however, I want to install PEX tubing, (or should I use CPVC piping?) secured to the horizontal roof joists. The crawl space is about 11' by 30' by about 3' high. It gets quite hot in the summer. I want to use it to preheat the water going into my natural gas water heater. It would have a way of removing the water in the winter, when the area would be quite cold, by taking this "loop" out of the hot water system using manually operated shutoff valves.
The crawl space area "produces" useable heat between April and mid-October.
Comments please on the idea.

Its a good idea, really. You would run it by water pressure, so that's taken care of.
If you could find some used tubing somewhere, a recyclers hardware store or the such, it would Help with the pay back period time. I myself would want a drinking water safe hose to be sure. If only for the lack of odor with it.
Often you can find Quality expensive building products, left overs and what not for a cut rate price. The more flexible the better, then you could wind it, the less joints you have to put in the pipe the better/ less potential for leaks it will be.

Water hose is safe CPVC probably smells ? not sure what it is, But anything with PVC in it is unhealthy.

Caution with the condens accumulating on pipe.

You could use some pex-a for underfloor heating.

I've wanted to do this for a while, but with my solar hot water panel setup I didn't see a need. My plan was to run ~300' of 1" pex (grade A, it has a higher pressure/temperature rating) to get a couple gallons of capacity (~9 I think). Drain it and bypass it for winter. I wouldn't use CPVC.

I am excited to see someone try it!