Dryer Heat Recovery and Dark Sky Lighting

These are two nice DIY projects from George Plhak's blog.

Dryer Heat Recovery Using a Furnace Filter

Venting clothes dryers to the outside is very wasteful.  It wastes the heat contained in the vented air stream, much of which could be recovered for space heating.  And, venting the air to the outdoors causes new air to be pulled into the house which then has to be heated to the house temperature by the furnace.  The energy wasted can be as much as 4 KWH per dryer load -- clearly one of the largest potential home energy savings available.

While there are various approaches to recovering dryer heat, the simplest one is to just vent the dryer air stream inside the house.  One problem with this is capturing the lint in the dryer stream so it does not end up in your house.  George has worked out a nice way to vent to the inside and to capture the lint using a furnace filter.  The furnace filter provides a lot of filter area, is easy to replace, and is inexpensive.

The dry vent filter box is on the wall next to the dryer.

The filter goes in a slot in the box.

Important Note: For some climates and some homes, venting the dryer inside can result in moisture problems, so if you go this way, be sure to monitor the situation after you starting venting inside.  Also, this is for electric dryers only -- gas dryers should never be vented inside.

All the details on George's blog ...

Another scheme that vents dryer air outside and recovers heat...

A DIY Garden Light that Preserves Dark Sky

This is a very nice design that uses inexpensive and recycled parts to make a low energy use (LED) garden light that does not allow any upward light radiation that would pollute the night skies.

The light in action.

It uses a used stainless steel mixing bowl and a jelly jar to hold the LED and reflect its light downward toward the ground.  Makes a very nice light pattern on the ground.

The mixing bowl and jelly jar to house the light 

All the details on George's blog...

George's blog has a lot of interesting material, including his extensive work on a DIY concentrating solar water heating collector.

Gary

June 17, 2014

A Large Shop Thermosyphon Solar Air Heating Collector

This is Ivan's large shop heating thermosyphon solar air heating collector.

It is 6 ft high by 40 ft wide. This 240 sqft of collector will likely provide in excess of 40,000 BTU per hour on a sunny winter day.

The finished 6 by 40 ft collector

These collectors are very effective heaters and since they rely only on thermosyphoning to move air through the collector they do not need any fans, controls, or power. The only moving parts in the whole collector are the simple backdraft dampers that prevent reverse flow at night. At about $3 to $5 per sqft of collector, these are one of the fastest payback solar projects that it is possible to build.

This is the south wall of the shop before the collector was added:

Ivan just built the collector right over the windows.  This allows a nice, wide and simple collector. I think this will work quite well as the windows will still get quite a bit of light through the collector absorber (which is two layers of screen).  How to handle existing windows is a question that comes up quite a bit in adding collectors, and I think Ivan's method is definitely worth considering.

The collector frame is built right on the existing shop wall.  The upper and lower vents that connect the collector and the shop are visible in the picture.  After the frame is done, the back wall is covered with rigid insulation, painted black, and then the two screen absorber is added, followed by the outer glazing.

The glazing being applied to the collectors, which already have the absorbers installed.

This diagram shows how simple the collector is.  The solar heated absorber heats the air, which rises out of the collector and draws new air into the bottom.  No fans, no controls, no electricity, no maintenance.

All the details on the collector build from Ivan...

Gary

June, 9, 2014

The Simplest Solar Water Heater

Carl came up with this very simple and effective solar batch heater that heats up one bucket of water. You put the 5 gallon bucket into the glazed box, put it in the sun, wait a few hours, and then take the heated bucket of water to where you need it.

Perfect for a cabin, emergencies or just locations without running hot water.

Its mounted on a turntable, so its an and advanced tech, human powered tracking solar water heater!

A piece of foam cut to fit the bucket reduces heat loss from the water surface.

Very nice and very simple.


In one test, the bucket water heated from 53F to 122F over a 7 hour collection period.

More details on construction and performance here....

Gary
May 31, 2014

Large DIY Solar Water Heating System in Virginia Using Commercial Collectors

Chris and Brenda are looking for ways to control energy expenses through retirement and built this very nice and very high quality solar water heating system.

While it is loosely based on the $1K design, it has a number of unique features that are aimed at achieving a long and maintenance free life.

The system uses two AET 40 sqft commercial collectors to provide plenty of hot water and the potential for some space heating later.  Using SRCC certified collectors has the advantage that the cost of the whole system will be eligible for the federal 30% tax credit.

Chris built the single pass heat exchanger form 3/4 inch copper pipe using soldered elbows to provide a hundred ft of effective length.

Making the heat exchanger

A MAXDTC controller was used to provide good control flexibility and to provide data logging for the system.

Chris worked out a ramp arrangement to get the 150 lb collectors up on the roof.  There is also a good description of the very nice mounting system.

Ramp and sleds being used to move collectors up to roof.

Chris put together a 13 page pdf that describes the system and performance in detail...

Gary
May 14, 2014

Bio-Home Open House in Lethbridge Alberta

Todd Hudson is having an open house on May the 23rd and 24th of his amazing Bio-Home in Lethbridge Alberta CA.

The house has a very impressive set of solar energy, renewable energy, and sustainable food raising/growing features -- read the brochure for the full story...

Highly recommended!

I've worked with Todd a little bit over the past couple years as he has worked through the designs for the dozens of unique features that the house has.  His ability to turn promising concepts into reality on the ground is very impressive.

The full flyer with all the house features listed and important parking and RSVP directions is here...

Joan and I will be there Friday afternoon -- please say hello if you come by then.

Gary

A DIY Solar Generator for Emergencies

John provides a very detailed description of a small and portable solar generation system that can provide power for emergencies or camping or routine use.

The system consists of a 45 watt PV panel, a charge controller to regulate battery charging, an off the shelf power pack that contains both the battery and inverter, and a PVC pipe rack you make to support the panel.

The system will provide power for things like a laptop, some modest lighting, charging cell phone batteries, and a number of other things that are very handy to have in an emergency.

The instructions are very detailed and the project is easy to build. A good way to get started with solar.

Thanks very much to John for providing this material!

All the details including a 34 page pdf here...

Four Interesting New Projects from Around the Web

This is a catch up on some new and interesting projects I've seen around the web and and added links to in Build It Solar.
Four very interesting projects...

George Plhak Releases Generation 2 of His Concentrating Parabolic Reflector Solar Array

I was very impressed with George's first generation parabolic solar array, and thought that the plans and documentation were very good.  His new generation 2 document and plan set are even more complete, detailed, and wide ranging.  

George goes over a number of design improvements, lessons learned, and provides much additional reference material for those interested in concentrating solar applications.

This is one of the very few cases where I think you get your moneys worth paying for project plans.

For all the details ....http://georgesworkshop.blogspot.ca/2012/08/diy-solar-parabolic-trough-20-intro.html

The Lucy Caliente Thermosyphon Solar Water Heater Plans and Construction Manual

This is a very detailed and free set of plans for a simple thermosyphon collector for warm climates (where no freeze protection is needed).

This is a simple system in which the collector is located below the solar hot water storage tank and thermosyphon flow from collector to tank does all the heating -- no pumps or controllers needed.  The hot water gravity feeds to showers or other places it is needed.  Fresh water is added to the tank via a float valve.

The full construction manual can be downloaded from the Linaria site...

I understand that the decoration on the tank increases the performance by 13%.

Making Collector Fins from Recycled Printers Plates

Water heating solar collectors require fins to transfer solar heat into the collector tubes.  Most DIY collector builders use aluminum fins and many ways have been worked out to make them.  

Soren has worked out a way to make solar collector fins from recycled printers plates.  He shows in detail how these free or nearly frees printers plates can be made into effective collector fins.

All the details here...

Thanks to Soren for sending this in!

Biomeiler -- Heat Extraction from Large Compost Piles

There is a lot of interest in extracting heat from large compost piles, but there is not a lot of detailed information online describing how to build a practical pile and extract heat from it.  This project describes in quite a bit of detail the building of a large compost pile with embedded tubes for heating water. 

The large ground wood compost pile in the making.  Embedded tube spirals heat water.

This large compost pile is said to provide temperatures up to 160F and last more than a year.

All the details here....  This is in German, but Google translator and lots of pictures help.

This is another project from the interesting LINARIA E. V. site...

Gary

April 10, 2014

Build-It-Solar Newsletter

Just started a newsletter for Build-It-Solar.

The plan is to publish the newsletter about once a month.  It will give a brief description of new projects added to the site over the month.  It may also cover some popular or seasonal projects -- and other things that seem note worthy.  Maybe some low tech cooling projects for next months newsletter?

You can sign up using the signup link just to the right.

Let me know if you think there are other things that should be included.

The newsletter is managed by the MailChimp service.  They appear to be responsible about not sharing your data.  You can unsubscribe with a single click at any time.

Gary
April 8, 2014

DIY Shower Water Heat Exchanger

When you think about what goes on energy wise when you take a shower, its mind boggling wasteful. Your hot water tank heats up several gallons of water from about 60F to about 120F typically using about 6000 BTU worth of energy. The water flows over you once, and then right down the drain taking nearly all of that 6000 BTU of energy you just put into it right down the drain.

Tyler has worked out a pretty simple heat exchanger to extract some of the heat from the shower water as it goes down the drain and use this heat provide some of the heat to the incoming shower water.

The grey water heat exchanger is inside the ABS stack on the left.  It joins the
main stack on the right near the floor.

The grey water heat exchanger consists of a bundle of PEX pipes.  The cold water on its way to the shower runs through this bundle of PEX pipes which are inside the gray water drain from the shower.  So, the outgoing hot water draining from the shower transfers some of its heat to the cold water that is on its way to the shower.

The bundle of PEX pipes ready to go into the drain pipe.

The bundle of PEX pipes being stuffed into the grey water drain stack.

Be aware that in many places this single wall heat exchanger design would not meet code.

Tyler gives quite a bit of detail on the construction and performance of the heat exchanger -- all the details here....

Please leave any comments or questions in the comments section at the link above.

Also at the link above is some more information and DIY and commercial grey water heat exchangers.


Gary
April 3, 2014

Storing Excess Daytime Solar Energy to Heat Greenhouse at Night

Russell has a unique and effective solar heating system for his greenhouse. On sunny days, the system takes excess heat from the peak of the greenhouse that would normally just be vented outside and uses a water to air heat exchanger to transfer this this heat to a large heat storage water tank. 

The heat stored in the water tank provides heat to the greenhouse on cold nights and cold cloudy days. The same water to air heat exchanger that stores heat is used to distribute heat to the greenhouse.

The solar greenhouse

In Russell's North Carolina climate, the system is doing quite well and is able to weather cold and cloudy days on stored heat.

The fan at the top of this picture pushes heated air down the duct and through the water to air heat exchanger that is just visible under the bench.  A pump circulates the warmed water to a 275 gallon heat storage tank behind the wall.

 The heat storage tank lives in the yellow structure that adjoins the greenhouse.

At night when the greenhouse temperature falls below a set value, water is circulated back to the water to air heat exchanger, and the same fan that pushes hot air through the heat exchanger now pushes cold greenhouse air through the heat exchanger to warm it up.

The full article gives more details on the greenhouse design, construction, schematics, and performance (which has been very good)...

Gary
March 27, 2014