The Everything Blog

More About the Solar Heater.

This solar energy project received second place in the 2007 Bordeaux Energy Colloquium's Annual Sustainable Energy Futures Casestudy Competition, an international competition for the most innovative renewable energy initiative.

Among the other contenders of the 2007 Sustainable Energy Futures Case Study Competition were:

* Electric cars in India
* Sustainable village in Mazatlan
* Palm oil biofuels in Laos
* Solar home heater in Canada (me!)
* Wave energy in Europe
* Biomass at a vineyard in the Middle East

The project exceeded proof of concept.

The furnace helped heat a 250sq ft room  and did so quite well even in intermittent sunlight. It does not replace conventional home heating. While the results were impressive, I have chosen to wait another year before rebuilding it.

Next Version

The next version will be self-sustaining. I've procured a small 12v battery and solar panel and will be installing them to power the thermostat and fans, replacing the 12v power supply. I will change how the glass sits on the chassis to ensure a tighter fit, but have no plans for reworking the galvanized or the chassis. 

Contact

Although I appreciate the email messages, I cannot respond to all, and generally do not respond to questions about building techniques or materials (that's what these  photos are for). If you like my project, go out and build your own. If everyone did, we'd actually make a difference. This isn't rocket science and I am no expert. I can not answer technical questions.

Media inquiries are always welcomed. 

Today I decided it was time for the first modifications.

Since this puppy works like a charm, I’ve decided to add a larger fan to the exhaust.

I think it will be able to maintain the additional airflow.

I’ve removed the lower glass panel, which had broken during the first installation.

Since I had a spare pane, today was the day to change it.

Here is the galvanized ductwork out of the heater and in the snow

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This was the perfect time for paint touch ups.

A little black paint and the blemishes are gone!

Electrical detail with the new larger fan (red and blue wires).  

Here you can see the thermostat, four small fans that connect the lower and upper collectors, and new larger fan to exhaust the heat into the house.

The very first collector on the bottom panel had to be custom fitted to accommodate the new, bulkier fan.

Using my aircraft aluminum shears, I trimmed away the back part of the ducting to rough in an opening for the fan.

Thank you very much for looking at my page!  

Blog about my project if you want, I appreciate any backlinks!

This PROJECT is now two years old. I welcome any comments but due to the volume, I cannot ANSWER them all. 

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More Results

This is the outlet inside the house.  Here, the thermometer shows the temperature of the air coming inside the house while the fans are blowing.

You’ll also notice the detail of the vent, which also houses the controls.

The pilot light indicates that the circuit is live behind the thermostat, which means the thermostat is over its temperature, currently set at 25 centigrade.

This one is just for a testament.  

You’ll see the inside temperature is 33 degree centigrade and the outside temperature is 3 degrees centigrade.

My fellow solar furnace friends do not be fooled. 

There is snow on the ground and the windchill was near -15 degrees centigrade.  Cold enough to freeze the balls off a brass monkey, but not cold enough to significantly effect the units performance.

Posted by babylakes at 03:15 PM | Permalink | Comments (1) | TrackBacks (0)

Day Four – the “Eureka Day”

I call this the Eureka Moment.

The whole unit was sitting on my deck, nothing was sealed, nothing was fitted.

What you are seeing are actual temps, the OAT Gauge is sitting on top of the glass, the digital thermometer is sitting inside the glass.

The outside air temperature was 9 degrees Celsius – and the internal temperature of the unit reached 37.1 degrees Celsius. The unit maintained over 25 degrees Celsius internal temperature for over three hours in intermittent sunlight.

Proof bonafide that the model works.

The Solar Furnace is now in its final position on the house.

Now that it is sealed, it will heat up and keep its heat much quicker.

It is ducted through the wall by a 3” galvanized, heavily insulated.

The Solar Furnace is bolted to the house using six #14 lag screws.

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Day Three – More Painting, Herringbone, Braces

Today I started by making four braces for the ducting. I made these out of corrugated plastic sheet, the type used in sign making.  

This will hold the unit together like a radiator.  It will also make the whole thing reversible.

Here you can see the ducting in place in the braces.

If you’ve done this right, the whole unit should be rigid and move easily as one piece.

Both radiators are now in place. Nice fit, and the braces will act as baffles slowing the air down.

But like I said  - reversible. Flip over and you can experiment with another finish.

..and I chose herringbone.

So one side of the collector will be black, and the other will be herringbone, leaving the galvanized exposed.

You can see in this bigger picture that I used auto detailing tape to detail the herringbone on the collector before painting it.

  The finished herringbone looks really sharp. The theory being that the metallic surface on the curvature will reflect light on it’s neighboring collector

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Day Two – Painting, Metalwork, and Electronics

The first task of the day was to paint the chassis black.  I’ve chosen matte black for the wooden parts, nothing special just a discount center spray can.  I’ve got High Temperature paint for the metal parts.

While the paint is drying, time to get to work on the radiator.  Instead of using beer or soda cans I am using galvanized 3” ductwork.  I’ve got 25$ worth at a local home renovation center.  I’ve cut 14 pieces thirty inches long.  This gives me a few extra inches at the top and the bottom of the box to louver the airflow.

Now the chassis is dry and a rough fit-in is done.  What you are seeing here are the 14 parts of the radiator, the painted chassis, and the glass panels.  Looks like a good fit!  I’ve used tape on the glass panels for illustration.

In theory, this type of convection furnace does not need any electronics, it works by the heating and cooling of air alone.  This picture shows you the exhaust air vent, which will direct warm air inside the house.  It’s been fitted with two pilot lights and an SPST switch, so it will also be the ‘control console’ for this.  I am using six-pair cat5 cable to connect everything.

I am using a digital non-programmable cooling system thermostat inside the unit. It connects through the hot side of the circuit that powers the motors.   This thermostat will only turn on the fans and the pilot light when the temperature inside the unit exceeds 25 degrees Celsius, blowing that warm air inside the house. Once the internal temperature drops again below 25C, the fans will stop.  I’ve set it that no cycle can last more than 6 minutes, to give time for the air to warm up inside the unit.

Two pilot lights mounted on the vent inside the house will give a quick status. Since only half the wiring is finished, the light you see on here is connected to the fan circuit.  It lights up when the fans are running.   The switch will be a power mains, and will also have its own pilot, currently not connected.

Posted by babylakes at 03:12 PM | Permalink | Comments (1) | TrackBacks (0)

Day One – Building the Frame

 I started by making an outline of these panes of glass I had lying around from an old sashless window that had been replaced. I have four panes, so there’s enough to risk using glass for now, I’ve got two extra panes.

Now I had an exterior frame nailed from the back of a piece of plywood with plenty of overlap. 

Remember, once the unit is sealed, you can’t open it to lag it to the roof or the side of the house.  The overlapping plywood will give me plenty of room to bolt this sucker down, hurricane proof!

A handful of SPDT and SPST switches, pilot lights and four 12v DC brushless microfans. All this stuff is from surplus stores. Total cost: 9 $

It still needs two small thermometers, and en electronic thermostat.   I will be using a surplus 12vDC power supply for now, until I get it completely solar.

Now I have a box that has an outer frame and inner skirt. The panes of glass sit on the inner skirt.

A brace in the center supports the two panes. It will also hold the fans and the electronics.

I’ve used tape on the glass, for illustration purposes.

Caulking, round one.   In order to be efficient, this baby has to be tight. This is round one of caulking.  The entire unit will be caulked again when the glass panes are placed for the last time.

Once in place the glass panes will be sealed to the inner skirt and nearly impossible to remove.

The four microfans mounted to holes drilled through the center brace. 

The fans will be connected to an electronic thermostat. When the temperature inside the unit is over 25 degrees Celsius, these tiny fans will gently move that warm air outside the solar furnace and into the house. When the unit can’t sustain 25 degrees, the fans will shut down and the unit will operate on convection alone.

Detail of the fans.   These were picked up for a buck each at a surplus store. They are not very high volume, which should help keep the air temperature up while moving it.

It’s important never to force hot air through a small opening. This creates a Venturi Effect, and the air looses its temperature from compressing and speeding up to fit in a confined space and then rapidly expanding and slowing down again.  

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