This post is the second in a 3 part series about high efficiency and solar water heaters. If you haven’t already read part 1, I recommend you do before continuing.
New water heater technology (continued)
What if we could heat our water with free energy that’s falling from the sky all around us? Well, we can!
Solar hot water heaters
As early as the 19th century, Americans were using the sun to heat our water. The earliest solar water heater designs were basic. They took a tank, painted it black, put it on the roof, and filled it with water. This same design — albeit with several important improvements, like a reflector and insulated box — is still sometimes used today. Known as an Integrated Capture and Storage (ICS) system, these are more simple and cheaper than some other, more elaborate designs. However, due to some important design shortcomings, they are only practical in moderate climates.
Passive vs. active solar water heaters
Solar water heaters have improved quite a bit since the ICS systems of the late 19th and early 20th centuries. Nowadays, most solar water heater systems are made up of two basic parts – a solar collector and a storage tank. This makes them more efficient and gives them more capabilities, but it also creates an issue: the system needs some way to move the water from the tank to the collector, and vise versa. Solar water heaters are first and foremost categorized by the method they use to achieve this movement of water – passive or active. In a passive system, water is moved by what is known as a thermosyphon. An active system, on the other hand, uses one or more electric pumps to move water.