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

Night Radiation Cooling of Water Flowing Over Roof for Space Cooling

David lives in Castlemaine, Victoria, Australia with hot and dry summers. He is working on a simple and inexpensive and very energy efficient space cooling system that uses water cooled via radiation to the night sky.

The roof spray tube and the collection gutter at the bottom of roof.

At night water is pumped from a tank to the roof where a spray tube trickles the water down the roof corrugations.  The water cools by radiation and evaporation as it makes its way down the roof.  At the bottom of the roof, a gutter collects the cooler water and returns it to the tank.  The next day, when cooling is needed the cooled water in the tank is used for space cooling.

Closeup of the spray tube in action.  Water is cooled as it flows down the roof.

The "coolth" storage tank.  In the final system, the tank will be located inside the living space.

In this trial system, the tank is a 275 gallon IBC tote located outside on the ground, but in the final system the "coolth" storage tank will be located in the living space so that it can directly cool the living space.

David is interested in hearing your thoughts on both how the roof cooling system might be improved, and how the cooling distribution inside the living space would best be handled.  He would like to avoid an active cooling distribution system and just let the tank (perhaps with a fan) radiate and convect  cooling into the room.  Will this work?  Comment here...

Gary
March 18, 2014

A Simple Solar Water Heating System for the Tropics

Peter lives in a remote and beautiful area of  Costa Rica and was looking for a simple solar water heating system that could be built with locally available and affordable materials.

Costa Rica home for the new water heater.

Peter worked out a simple thermosyphon collector design that heats water in an elevated tank.  The tank gravity feeds to showers. A float valve arrangement at the tank automatically keeps the tank topped up with water.

Because copper is very expensive locally, he used CPVC pipe for the collector.  Normally CPVC would not be a good choice for a glazed collector that sees this much sun because of the potential for overheating damaging the CPVC pipe, but Peter has worked out a couple of reliable mechanisms to keep the collector temperatures down.  He allows for some circulation of air under the collector glazing, and the thermosyphoning of water from the collector to the tank coupled with the un-pressurized tank insures that the water temperature will not exceed 212F.  Both of these protection methods are reliable and don't depend on electrical power or pumps or controllers (which are all subject to failure).

The collector absorber before painting

The gravity feed hot water tank with float valve

The completed system.

Peter provides a detailed description of the design and build and the challenges in finding suitable materials ...


Gary
March 6, 2014

Gordon's Deep Energy Retrofit - After 5 Years Report

Back in 2009 Gordon and Sue did a full deep energy retrofit of a 1963 brick schoolhouse making it into a very energy efficient home.

The retrofit include R40 Larsen Truss walls, triple glazed R6 windows, a passive solar window scheme, a new solarium, solar water heating, and a hand crafted masonry heater.

The new solarium

They have been in the home for five years now and this full report describes on how things have worked out along with a well kept record of energy savings -- all the details after five years here...

The whole retrofit project is described in detail here...

The Larsen Truss Walls

Thanks very much to Gordon and Sue for providing the update.

Gary
February 27, 2014

A Solar Heated Loo

Michael has developed this simple and elegant solar heated version of Arbor Loo that has many advantages as well as offering a little more comfort on those cold mornings.

The Arbor Loo provides a efficient and sustainable solution to the poop problem, saving thousands of gallons of water a year and providing useful tree planting compost.

I really like the nice simple space heating system.  It is a drain back system with the collector nicely integrated with the roof.  An IBC container is used for heat storage.  And, by leaving the insulation off the parts that face the "living space", the IBC also provides the heat distribution.

The only moving part is the pump -- no controller, no antifreeze, no heat distribution controls or pumps -- very simple.

I think that this kind of design could be applied to other simple space heating needs.

The loo under construction with the IBC container at the back (providing a heated backrest for the toilet seat).   I like the way the structure integrates the standard size door, collector, IBC and toilet seating area with no wasted space.

Full details on the build and performance of Michael's solar heated loo ...

Thanks very much to Michael for providing this material!

Gary

DIY Ground Source Heat Pump + PV Array -- No Heat Bills!

In this very ambitious project, Jerry goes through all the details on installing a 5000 watt PV system and a 2 ton Ground Source Heat Pump. Together they provide all of the space heating and cooling and hot water.  

No heat bills and very low emissions.

The ground loops for the Ground Source Heat Pump

Jerry started by installing a 5000 watt PV system on his garage roof.

5 KW grid tie PV array on garage roof.

The PV system is grid tied and uses an Aurora 6000 watt grid tie inverter to produce house power and to interface with the grid. Jerry is paid 14 cents per KWH generated via the net metering agreement with his utility and is also able to sell SRECs to the utility to allow them to meet their renewable energy generation requirements with the state of NJ.

The 6000 watt grid-tied string type inverter for the PV system.

Once the PV system was installed, Jerry installed a Ground Source Heat Pump to efficiently use the PV generated electricity to both heat and cool his house. The GSHP installation involved digging a 300 ft long 8 ft deep trench, laying out the ground loops in the trench, installing the 2 ton heat pump.

The 300 ft long trench for the three GSHP ground loops.

The 2 ton ClimateMaster water to air heat pump.

In addition to installing the 2 ton heat pump, Jerry also designed and installed a duct system to distribute heating and cooling to the house.

All the details on the DIY GSHP + PV system in a 26 page pdf...


Gary
January 22, 2014

Building Large Cylindrical Tanks for Solar Heat Storage

Alan Rushforth of Rushforth Solar provides detailed information on building large cylindrical water tanks for storing heat. These tanks are commonly used to store heat generated by an array of solar collectors in space and water heating applications.

One of Alan's tanks

The tanks that Alan makes typically range from a thousand gallons up 4000+ gallons, but the design could certainly be used for smaller tanks that would be typical of residential solar applications.

This design is very structurally efficient, light weight, and material efficient.

The tanks consist of aluminum  sheet wrapped into a cylinder, which is then lined with rigid foam board insulation.  

The outer aluminum sheet wall with layers of insulation inside.

An EPDM liner is then installed to contain the water.

The EPDM tank liner being installed

Alan also includes some very helpful material on building heat exchangers for these large tanks.

Thanks very much to Alan for providing this material!

Stainless steel pipe coil heat exchanger.

Alan's full description on building these tanks ...

Gary

Home Power Digital Subscription Deal

I don't usually do deal announcements, but could not pass up this one.

Home Power Magazine is doing 50% off their digital subscription rate for a while.  So, a 3 year digital subscription that also includes access to 20+ years of back articles is now $11.95 -- what a deal!!

https://www.homepower.com/subscribe-and-save?template=subscribe

If you are not familiar with Home Power, its probably the best source out their for detailed articles on DIY solar and other renewable energy projects -- aside from Build-It-Solar of course :)

Gary