Does anyone use Solar for hot water?

[brucefla]

Was in the back with a friend thinking of trying to increase my hot water output/recovery time.

He said we can run 300' (6 50' coils) of 1" copper tube on the roof and capture approx 30 gals. of heated water. We would just put this in the loop before it goes into the tank. He said with proper insulation and design, we should easily be able to store this water at 80-100 deg (depending on the sun and heat that day.

A temp switch would be installed that would only open when the coiled water is a certain temp.

The theory seems good so far. Just wondering if anyone does this? My current water heater is only like 3 years old, so my options seem to be either:

Daisy chain another heater/add a storage tank/add box booster/
go solar. (I have limited backroom space)

I like being green if possible, and there are state and federal tax credits.

[Anonymous]

Conceptually it would work, but you might need to add a pump. A one inch line would not handle your total water needs, assuming a decent size mat. Thus, you would need to put this thing in parallel with your normal supply and add a booster pumpt to force feed it into your system.

[Lar Hylobates]

This water system is not like a pool. Cold water is constantly flowing through and into the system.

A pool works as once the water is "warm" it merely needa a maintenance of heat to keep it warm.

If you can maintain appropriate flow levels it is a good thing, but I doubt there will be much overall energy efficiency or at least not enough to justify the cosy of installing and maintaining such a system.

If you figure it out and it is cost effective, I'll be the first to install as I have a huge flat roof. A little tilt to the south and I'm in business.

[Andy]

The only way I could heat coils full of water on my roof is if I lit the roof on fire, otherwise they would freeze solid, rupture and flood the building.

[Duane]

I have done some research (just a little) and found that there are two main types of solar water heating.

The first is for climates that are warm year around with little chance of freezing. It is similiar to what is described below in that you just run your water line through a box (rooftop, back yard, anywhere) with glass on top and all the pipes and backgrounds are painted black to asorb the heat.

The second is for all climates and uses the same set up as above, but instead of water it uses an antifreeze on the roof and it transfers the heat from the antifreeze to your city water by a heat transfer tank. Basically a water tank with two intertwined coils inside that lets the cold city water asorb the heat from the antifreeze. This is a closed system and the antifreeze is recirculated via a pump. A lot of times the pump is just a small 12 volt pump that is hooked up to a solar panel and runs when the sun is out.

Which ever you decide to use keep a few things in mind:

You now have components outside that can be damaged by vandalism, weather, etc., so make sure you install several valves that can be closed to isolate and bypass the solar heater in case of damage, leaks, or ??

A solar heater can, during a sunny summer day, produce very hot water. So hot that it can burn someone easily. An anti-scald valve should be installed to regulate the heat coming in from the solar heater. This takes some extra plumbing, but should be used.

An expansion tank should also be used.


Search the web and you will find some good information. At this time I believe there are some good "bolt in" solar water heaters that would do a great job, but are still just a little too expensive to purchase. Another year or two of high gas prices may make them more affordable.

Duane.

[Kitty]

In the 70's there was a huge tax advantage to do this, and one store BD's parents had, had this. It was useful and ran well for many years. However, it was fairly expensive and fairly expensive to fix after the years of use. Without any additional tax advantages they felt it was no worth fixing. Two years ago when we redid the roof at this particular location is when they finally choose to get rid of the useless things.

[pete f]

I looked into solar water for l'mats some time back, because of the flow needed it would was going to be a huge amount.
Tankless heaters for me were much more of a bargain.

If you really wanted to try it you could run water thru black painted CPCV pipes all over your roof and then into your hot water heater, kind of a pre heat. You would need a blow valve for when they got real hot.. and a circulator pump.