Friday, June 20, 2014

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.




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 


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


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Monday, June 9, 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.



Gary
June, 9, 2014
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