Solar Hot Water - Finishing Your System

In this fourth article in our series on solar hot water heaters we will finish our passive collector box, and plumb it into our existing hot water tank. In the previous article we built our collector box, lined it with reflective material and attached it to the roof. We are now ready to mount the tanks into the box and plumb them into the house.

Each tank must be secured inside the box in such a way that they cannot move once they are filled with water. Here we will build a mount for them using a length of 2x6 mounted to the bottom of your box. Use heavy duty triangular brackets screwed not only to the box, but into the joist of the roof so that they form a shelf capable of supporting the weight. I also recommend using strapping such as plumbers tape across the top and bottom of each tank to help hold them in place, you can't be too careful.

Now that you have your tanks securely fastened down, it's time to plumb them in. It isn't any different than plumbing a single tank in your house, cold water goes in at the bottom and hot water comes out at the top. Bearing this in mind, turn your house water supply off before you start, since we will be cutting into the supply line to your existing hot water heater. Attach a new length of pipe from here to the cold inlet of your first tank in your roof top box; this will be your new supply line. Run a line from the hot outlet of tank 1 to the cold inlet of tank 2 and then a line from the hot outlet of tank 2 to the cold inlet of the tank in the house. There you have it; you are now plumbed in, if you live in an area that is prone to freezing, you will want to install shut off valves and drains in these lines so that you can drain the system.

For the final phase of this project you need to cover the box with the sheet of Plexiglas to seal all your hard work for the elements. I recommend that you make this a hinged lid setup so that you can get in and service your tanks if they need it. However, it needs to be as watertight as possible so that your box does not collect water. A small series of drain holes in the bottom wall is a very good idea since there may be the possibility of rain getting in or condensation build up.

One other thing you might consider depending on where you installed your passive collector; is building an insulated hinged lid that can be lowered down over the face to help keep the heat in overnight. With a little care in the building and very little maintenance this simple solar hot water system should give you years of free hot water, as long as there is a little sunshine. For those days when there isn't enough sun you are still connected to your original hot water heater, it will come on and heat your water.

One other thing to consider; helping make this system even more environmentally friendly as well as cost effective, is to replace your hot water heater with an on demand hot water heater. These units are designed to only heat the water when a tap is turned on and can be turned off when your new solar hot water system is working. I hope these articles have helped you to make the choice to "go green" and enjoy plenty of free solar hot water.

Sources: www.motherearthnews.com , www.eere.energy.gov