Thursday, August 26, 2010

A solar water heater from trash for your RV

Solar hot water heaters use the sun to warm up water in a collector to provide hot water with no use of your fuel. The principle behind the collector is very simple and many materials can be used to build one. Someone in China has used beer bottles in their design and the Brazilian army used beer bottles and milk containers to heat water for 50 soldiers. There are instructions for doing this is you decide you want a cheap hot water source.

How does the soda bottle collector work?
The heat of the sun is absorbed by a black pipe that is filled with water. In order to increase the heat you surround the pipe with a soft drink bottle to provide insulation. The insulation lets sunlight in and traps the heat so it works like a greenhouse. You can use pvc pipe painted black or copper pipe painted black. The rule of thumb is 1 square foot per 2 gallons of water. So if you want to heat 8 gallons, make the collector 2 foot by 2 foot. Cut the bottle at the top and bottom then glue each bottle together.

Many bottles will work
You can add as many pipes as you would like and make them as long as you would like to get the amount of water you desire. However, when boondocking you need to conserve water, so don't make it too large. Any bottle made of glass or PET can be used to insulate the pipes so you have a lot of material to select from. The picture shows green beer bottles that someone in china used to heat water. Whatever you select, this is a good way to recycle material that would only end up in the land fill. In addition, you save propane.

Themosiphon connection
When taking advantage of the thermosiphon technique, the cold water input needs to come from the bottom of the tank and the hot water returns to the top. The collector needs to be lower than the tank for this to work. A thermosiphon technique is good because it doesn't have a pump that uses up your battery and could fail.

The bottle over pipe collector is just one way to get low cost hot water but it is rather easy to implement without any special tools. If you want to experiment, this is a great way to do it without spending very much money.


  1. Very interesting concept

  2. Using the sun's clean renewable energy to heat water is good for the environment because it reduces several forms of air pollution and helps to reduce demand for new and often environmentally threatening supplies for fossil fuels. Thank you for bringing more information to this topic for me. I'm truly grateful and really water heating


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