Hot Water

[dieselscout80]

I want to try to decrease our cost to heat hot water, but I'm not ready to build/buy a solar hot water heater.

Would it be worth it to run my water supply line for my current hat water heater up into my attic, so durning the summer the attic heat could prewarm the water from our well?

Would this be worth the effort for us since we live in South Carolina and its a bit warm here in the summer?

I know I'd have to install valves to keep the water out of the attic in the winter.

Would I get enough heat transfer with PVC or would it require a copper loop?

 

[Stimw]

Unless you ran a lot of water line it would not make that much difference.
If you google you can probably find simple directions to build an inexpensive solar collector. With that and some temp controled valves you can have an efficent system. Heating water is the most efficent use for solar.
I took a class on Solar Energy about 30 years ago and told a friend that I was taking it. He told me "just put some car seats on your roof and run water accross them! They always seem really hot to me!" .

 

[/pine]

Does the W/H have a insulating blanket ?...
Using all cold water wash cycles will help a little...

 

[dieselscout80]

Does the W/H have a insulating blanket ?...
Using all cold water wash cycles will help a little...

Yes it has a insulating blanket and we wash everything, but whites on cold.

I was thinking that if I put a 300' coil of 3/4" or 1" PEX in the attic it would have a bit of warm water before the cold well water hit the hot water tank.

 

[Workstead]

If you put the coil on the roof outside you will get the water even hotter.

 

[CNC Dan]

If you put the coil on the roof outside you will get the water even hotter.

... or on the ground. Anywhere the sunlight can get to it. Add a sheet of clear plastic to keep the wind off it and you might not use the water heater at all. At least not during the day. Have to take it in when it might freeze.

 

[Redneck in training]

to pass water from the well will not make much difference. What you might do is either put heat exchanger in the attic or on the roof or wherever place that makes it practical and circulate the water through it when it is hotter than the water heater. What you need to do is to connect one pipe (cold) to the water heater drain and the other T in the cold water intake on the top. The install small circulation pump in the anywhere in the loop. And temperature switch with two sensors that can be programmed to recognize that the water coming from the heat exchanger is hotter than the water leaving the water heater. The heat exchanger in te attic would have to be rather large but it doesn't have to be pretty.
Here is an example of switch
Series TSS2 | Dual Stage Temperature Switch | Dwyer Instruments I bought this one for $40 in 2004 but they are about twice as much today. Or Google "differential temperature controller" for more choces.

and an example of the pump

WebCAPS 2013.02.032 - DB Week 8 Published - Customized for Grundfos USA

 

[jimgerken]

TO the original poster: I like the idea! It would be more work, but think about using copper, and instead of it just hanging in the attic, it attaches to the underside of the plywood roofing somehow. I wonder if that flat fin stuff you can put on tubing to attach it under wood floors for radiant floor heat transfer would work. You know, the roof decking plywood is really hot all the time in the summer daytime, so the conduction into the copper would be great. I would think the conduction from the wood decking plywood would be much more effective than transfer from the attic air (air is an insulator). Maybe PVC or PEX would work too, I dont know. The insulation value of the plastic compared to the copper just means it takes time for the transfer, but it will transfer. You better do some experiments and get back to us.

 

[CliffordK]

If you do just a single loop of pipe, that loop of pipe will cool down just about the time you're finished flushing cold water from the pipes and get some hot water into your shower.
Perhaps a small tank would warm up somewhat on a warm day, assuming you're planning to use the water at night.

 

[Redneck in training]

TO the original poster: I like the idea! It would be more work, but think about using copper, and instead of it just hanging in the attic, it attaches to the underside of the plywood roofing somehow. I wonder if that flat fin stuff you can put on tubing to attach it under wood floors for radiant floor heat transfer would work. You know, the roof decking plywood is really hot all the time in the summer daytime, so the conduction into the copper would be great. I would think the conduction from the wood decking plywood would be much more effective than transfer from the attic air (air is an insulator). Maybe PVC or PEX would work too, I dont know. The insulation value of the plastic compared to the copper just means it takes time for the transfer, but it will transfer. You better do some experiments and get back to us.

You can use a car radiator(s) or similar and blow air trough them outside of the attic. It will serve two purposes heat recovery and cooling the attic