DIY





Build a Simple Solar Air Heater

This low-cost solar air heater plan lets you turn any south wall into a source of free heat.

| December 2006/January 2007

After walking into my workshop one December morning and feeling a bone-chilling 10 degrees, I decided to install a heating system. Given the rising costs of propane and my family’s environmental concerns about using nonrenewable fossil fuels, a solar solution seemed fitting.

I’m a retired aircraft engineer, but you don’t need a similar background to tackle this project. In fact, a solar air heater built into new construction or added to an existing building can be an easy and inexpensive heating solution. Following the simple principles and plan outlined here, you can heat your workshop, barn or even your home with free heat from the sun. If it works here in Bozeman, Mont., it’s bound to work wherever you are.

I reviewed many solar collector concepts and decided to install a thermosiphon air collector on the south wall of the workshop. The elegant, simple thermosiphon design uses only the buoyancy of heated air to create circulation through the collector, eliminating the cost, maintenance and power consumption of fans, sensors and controllers commonly used in other collector designs. On a sunny day, in a cold climate like ours, this simple system can produce heat equivalent to burning about $2 worth of propane (equivalent to about $3 for natural gas).

To minimize costs, I integrated the collector with the structure and used readily available materials. It cost me about $350 and took only one trip to the hardware store. I built and installed it in about three working days. Follow the suggestions below, and you may be able to do it faster!!



How It Works

The thermosiphon collector consists of clear, corrugated polycarbonate panels fastened to 2-by-6-inch studs. The clear panels admit sunlight, and an absorber suspended inside the collector captures the sun’s heat energy. The air around the absorber warms, expands and rises, creating a convection current. Vents at the top and bottom of the collector allow air to circulate through it. Cool air enters the lower vents from the interior, is heated by the absorber, rises to the upper vents and returns to the interior. Air circulation continues as long as the sun shines on the collector.

At night, airflow reverses as air in the collector cools to outside temperatures. Simple flapper valves on the top vents stop this reverse circulation and keep the heat inside.

Jack Jones
5/5/2018 8:22:55 AM

I used the plans at WWW.EASYWOODWORK.ORG to build an air heater – I highly recommend you visit that website and check their plans out too. They are detailed and super easy to read and understand unlike several others I found online. The amount of plans there is mind-boggling… there’s like 16,000 plans or something like that for tons of different projects. Definitely enough to keep me busy with projects for many more years to come haha Go to WWW.EASYWOODWORK.ORG if you want some additional plans :)


www.EasyWoodwork.org
5/5/2018 2:39:43 AM

I used the plans at www. EasyWoodwork.org to build a solar air heater – I highly recommend you visit that website and check their plans out too. They are detailed and super easy to read and understand unlike several others I found online. The amount of plans there is mind-boggling… there’s like 16,000 plans or something like that for tons of different projects. Definitely enough to keep me busy with projects for many more years to come haha Go to EasyWoodwork.org if you want some additional plans :)


gordy
10/6/2017 11:49:17 AM

This story is from December 2006/January 2007. Gary has continued to work on solar heaters, visit his web site builditsolar.com for better heater designs. Or a sister site simplysolar.com . Thermosiphon collectors do work, BUT a lot of heat is lost through the glazing because of the high temperatures in the collector. To get the most BTU's from your collector you are better off putting fans on the unit and getting a large volume of cooler air (100f to 120f), than getting a small volume of hot air (180f and higher). The cooler you can keep the collector, the less heat escapes it to the outside. I use 2 computer fans (50 cent each at a flea market), powered by 2 - 7 watt solar panels, and controlled by a snap disk switch normally open (N.O.) close on rise at 85f (turns on) and opens on fall at 80f (turns off). The switch is in the collector at the top. Gordy







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