DIY Barrel Stove Outdoor Furnace

The Conceptualization, construction, and continuous improvement of my DIY Barrel Stove Outdoor Furnace


DIY Window Mount Solar Air Heater Presentation


I have been fond of building solar air heaters for many years. Over time, I have built several types of solar air heaters with great success. In this post, you will learn some solar air heater basics as well as my specific implementation currently in operation at my home. My personal implementation of a solar air heater is the DIY Window Mount Solar Air Heater. This means that my solar air heaters are designed to be press-fit into the window frame inside my home.

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For your convenience, here is a list of some of the materials that are used to construct this device:

ID Name Description Link
1 4 inch round louvers Required for the air intake and exhaust [#AD]
2 Attic Fan Thermostat Required to automatically turn on / off the circulator fans [#AD]
3 12 Volt AC Adapter Required power source for circulator fans [#AD]
4 12 Volt DC Fan Required for air circulation [#AD]
5 DC Power Connector Jacks Used to elegantly connect DC Power Supply to Solar Air Heater [#AD]
6 Speaker Terminal Cups Another elegant method of connecting DC Power Supply to Solar Air Heater [#AD]
7 1/2 inch rigid foam board Core building material for the solar heater body [#AD]


At a high-level description, you can build a device that uses solar exposure to help heat your home.  As long as you factor in a few design principles and variables, you too will be able to help heat your home using the sun’s exposure. Here are some important factors for success:

  • Solar Exposure – You need to have direct sunlight for as long as possible in order for this to work. In my implementation unfortunately, I do not have directly facing SOUTH windows. I have to use my large SOUTH-EAST facing windows. This means that the maximum TIME factor for solar exposure is from 7:45AM until 1:30PM. The rest of the day the sun shines on my SOUTH-WEST wall, which I do not have any decent exposure due to trees and other obstacles. If you have a complete SOUTH facing wall without any obstacles, you will have the longest solar exposure possible, therefore generating the most heat.
  • Surface Area – My windows are a significant size, therefore I am able to generate a decent amount of heat. The idea is simple: the greater surface area you have, the greater amount of heat you can collect to heat your area. I once built a very beautiful and advanced window mount solar air heater in a 2 foot x 3 foot window and its heat generation was insignificant. I ended up removing it.
  • Window Styles
    • Single-Pane older non-insulated windows – Window Mount solar air heaters that I built under this configuration have been the most intense heat-generating devices! In fact, I bordered on the limits of safety! In one installation, the solar heater generated so much heat that I ended up melting the window plastics as well as boiling the sap out of the window’s wooden framework! Old single-pane windows without any LoE coating or argon gas injection are essentially like a magnifying glass against your solar air heater! Loads of heat but dangerous!
    • Modern multi-pane, insulated, argon gas filled, LoE coated windows – These windows definitely suppress the solar exposure, but provide safety. This is a more reliable configuration.
  • Electronics – There is a very important reliance but very simple implementation of electronics in this solar air heater. This is important to create a system that thoroughly circulates the heat into your room. This system uses simple computer fans, an attic fan thermostat, and 12VDC AC Adapter to power everything. I have built passive systems (without electronics) that just did not heat the room enough. This is a similar paradigm as using a circulator pump on a hot water heating system as opposed to just using thermosyphoning. The pump is much more thorough.

My home does not really have a wall that is South facing. I had to work with what I have and install the heaters on the SOUTH EAST wall’s two large windows. 


This ONE SINGLE window mount solar air heater SINGLE-HANDEDLY heated the entire first floor of my other home to around 74 degrees F thanks to it being mounted in a single-pane, old-style window frame! This is the window whose plastic melted and the wood framing tree sap was boiled out into an oozing, sticky mess! Pretty scary and very powerful! This unit used aluminum soffit material for the heat collector:

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Building the Window Mount Solar Air Heater is quite simple. Construction materials and electronics are very simple and low-cost. The main component is rigid foam board for the body, metal heating elements used to absorb and collect the solar generated heat, a few 12VDC computer fans, an attic fan thermostat, some wiring, 12V AC Adapters, some aluminum HVAC tape, construction adhesive, and some beautification materials of choice (contact paper, cloth, etc) to make it look nice.

Make a rigid foam board box that press-fits into your interior window frame:


Attach metal fins (various materials such as flashing, flattened beverage cans, soffit, etc) to interior with construction adhesive:


Install and wire fans and thermostat:


You can adjust the thermostat to engage when the internal air heater temperature reaches around 80 degrees F:


Paint the interior with high-temp black paint:


I used old curtains for beautification. You can use your imagination here.



When heating season comes along, you can install the solar air heaters into your windows, plug in the power supplies, and let them run! Once the warm weather starts to come along, you can simply remove them and put them in storage! I store mine in my basement. Very simple!

My left heater:

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My right heater:

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As long as you have solar exposure and no overcast days, you can see a significant savings in your energy expenses. After several years of use, I can say on average I save around $40.00 to $50.00 per month during the heating season. During the cold season, my first floor heats up to a maximum of 71 degrees F all through the solar air heaters. I have observed that I get maximum solar gain whenever there is lots of undisturbed snow covering the ground during a clear sunny day. This causes an effect where additional sunlight is reflected off the snow onto the front of my house. This increases the surface area factor of this entire process. I COULD reproduce this by covering my entire front lawn with shiny, reflective aluminum sheets 🙂 but that would not be practical!

This year so far (2014-2015) has very little solar exposure and many overcast days. My solar air heaters do not engage often due to this weather. HOWEVER, this is also my first time using my DIY Barrel Stove Outdoor Furnace, so THAT has dramatically reduced my heating expenses in itself! These units have paid for themselves many times over for the few years that I own them. It is a lovely feeling to walk downstairs into a very nice warn and toasty heat that envelopes your body!

If you prefer to watch videos on this topic and get a deeper understanding, please visit my YouTube channel and review the various related videos pertaining to this topic: