A Unique and Cost Effective Solar Space Heating System

Taylor's space heating system has a couple of unique features that I like and think are worth taking a look at if you are planning a solar space heating system.

He describes the system on his blog here...

One of the unique features is the use of inexpensive pool heating collectors.  He adds polycarbonate glazing to the collectors to get the performance up in the same area as commercial glazed space heating collectors.  The danger here is that if the collectors are stagnated (no flow), the temperatures inside the collector can get high enough to damage the the polypropylene pool heating collector.  To avoid this he fits the glazing with some air leakage paths to bring the stagnation temperatures down.

The glazed pool heating collector.

This is the same idea that I have been looking into on our new inexpensive, off-the-shelf solar water heating system.   I think this idea has a lot of promise for getting solar water and space heating costs down.  But, bear in mind that its still on the experimental side.

The other feature I like in the system is that Taylor uses a commercial off the shelf water to air heat exchanger to distribute the solar heat to the house.

The water to air heat exchanger -- has to be one of the funkiest looking ones ever!

Even with the relatively low temperature hot water that solar heating systems typically provide, these heat exchangers will deliver quite a bit of heat.  On Taylor's system, the airflow through the heat exchanger is driven by a fan that is PV powered.

One thing to bear in mind about heat distribution for solar heating systems is that unless you have an exceptionally well insulated house, or a very large solar collector array, the solar heat will be a supplement that reduces your heating bill, not your only source of heat.  This being the case, the thing you want the heat distribution system to accomplish is to be able to always deliver the solar heat you collect during a day to the house during that day and through the night.  Its not important that the solar heat distribution system be able to supply the whole heat loss of your house on a cold day -- you have a furnace for that.  What's important is that all of the solar heat that you collect gets delivered to the house overnight.  This can make a world of difference in the size of the distribution system needed.

For a ton of other solar space heating systems and ideas go here...


Gary
December 17, 2012

DIY Heat Recovery Ventilator (HRV)

An HRV pulls fresh air into the house and exhausts stale air to the outside.  In the HRV, the fresh and stale air pass through a heat exchanger that recovers most of the heat remaining in the stale air to heat the incoming fresh outside air -- thus providing a significant saving in energy to heat the incoming air.

While I've been looking for material on building an HRV, I've not had much luck in finding anything that appeared to have a chance of working well over time.  This book from William Shurcliff that has a little on a DIY design, but its pretty minimal.

Paul from BC noted the above page and came through with the article below describing an HRV design that uses sheets of Coroplast material for the heat exchanger.  Paul actually built one of these for his own house some time back and it worked well for the time period he was in that house.  It seems to me that the Coroplast has a descent chance of holding up well in the somewhat hostile (wet and even icy) environment inside an HRV heat exchanger.  Thank you Paul for sending this in!

The Coroplast HRV design

Full details on building the Coroplast sheet HRV...

New section on HRV's ...

A completed HRV

Gary
December 8, 2012

Solar Greenhouse Research -- No Heat Needed

Here are three solar greenhouse projects just added to the site.  One in Missouri, another in Manitoba, and our new solar greenhouse in Bozeman.

Solar Greenhouses are roughly defined as greenhouses that can grow things through the winter without supplementary heat -- that is, they are 100% solar heated.

A University of Missouri Solar Greenhouse with 18 Year Track Record

This is a greenhouse I ran across while looking for a good design for our own solar greenhouse project.  It was designed and built by the Univ of Missouri extension about 18 years ago, and has been used for researching winter greenhouse growing since then.  

Its designed to work well through the winter with the steeply tilted, double wall glazing, the north roof sloped to reflect light on the growing area, all surfaces insulated except the south glazing, and thermal mass in the form of water barrels.

It successfully grows through the winter with no supplemental heating.

We liked it enough to model our solar greenhouse (see below) generally after it.

For all the details...

Solar Greenhouse Research in Manitoba

These are some articles and a paper on a solar greenhouse research project in Manitoba.  Part of the project involved taking a wide greenhouse and subdividing it into 4 separate, side by side spaces.  Each space was used to test a different glazing or insulating scheme through the winter.

Links to two articles and a paper on this project here...

Solar Experimenation "Thing" in Montana

This is our new solar greenhouse project here in Bozeman.  It is actually a scaled down version of the U of M greenhouse above.  

While its intended to be our greenhouse for the long run, we plan to first use it to do some testing of the performance of low thermal mass sunspaces attached to a house and used for space heating of the house, and then for testing the idea that it possible to build a small (tiny) room in one end of the GH that will be able to maintain a comfortable temperature through the winter on just solar.  This is a tall order in our climate, but we will see what can be done later this winter.

The GH with its 60 deg tilt, south facing glazing -- all other surfaces are insulated.

Building the frame

Temperatures in the first three days after being closed in.

30F outside -- 120F inside.

Any ideas or suggestions on this project would be appreciated.

All the details here...

Gary

Large DIY Solar Space and Water Heating System in Maine

Steve has designed and built a very nice solar space and water heating system in Maine.   The system has a number of interesting and unique features including,

• A large "hizer" collector with full width "risers" running horizontally.
•  Integration of the solar heating with the existing boiler.
• A Steve made controller for the system.
• A new technique for making the PEX heat exchangers.
• Drain back of the collector to a tank 70 ft from the collector.

The 28 ft wide Hizer style collector

The collector is 28 ft wide and is built as a single "hizer" style collector rather than 7 or so side by side vertically oriented collectors that would normally be used.

Picture with glazing off showing the Hizer style "risers".

Building a wide collector like this as a single unit and with the horizontal "riser" layout simplifies the plumbing, reduces labor, reduces material needed, and reduces the cost of the collector.

In this system, the solar heat source and boiler heat source are integrated into a single heating system.   And, the system also provides domestic water heating.

System diagram showing integration with existing boiler system.

Steve worked out a way to recoil the PEX heat exchangers to improve heat transfer and make them more efficient.

The tool for recoiling the PEX to make more efficient heat exchangers.

The system uses a Steve designed and built controller.

Circuit diagram for the system controller.

All of the design and build details are provided in a 15 page pdf that can be downloaded here....

Gary

A Unique DIY Solar Pool Heating Collector Using PVC Pipe

This pool collector is a different slant on pool collector design, and may have some unique benefits for some people.

In a nutshell, the collector consists of large diameter supply and return manifolds that are connected by closely space half inch PVC pipe risers.  The manifolds supply water to the risers, which pick up the solar heat and deliver it to the pool.

The half inch PVC risers are attached to the PVC manifolds by drilling and taping a half inch NPT pipe thread in the manifold for each PVC riser pipe.  Then male threaded to PVC adapter fittings are used to attach the half inch PVC to the manifolds.  This is a nice, simple, reliable and inexpensive way to make the collector.  Since the collector is custom made, it can be built to fit the roof space available.  The riser runs can be made quite long, allowing one large collector to be used instead of several smaller one.

The standard mat style pool heating collectors may be a better choice if they are readily available where you are and can be fit into the space you have.  Matt came up with this design because he was in a country where the mat style collectors were not available at a reasonable price, and this design proved to be a good alternative.  The cost may end up being more or less than the mat collectors depending on where you are and how big the collectors are.

The pdf that Matt provides has a great deal of good detail on the design and build for the collector and provides plenty of detailed instruction for people who have not worked with PVC before.

All the detail on this PVC pool heating project here...

Gary

Off-The-Shelf DIY solar water heating -- Version 2

I've had a bit of a reset on the Off-The-Shelf solar domestic water heating system.

The idea of this system is to provide a very easy to build DIY solar domestic water heating system that uses off the shelf collector, tank, controls, etc.  -- a system in which you just install the off the shelf components rather than building your own collector and tank.  The objective is to keep the total cost to about $1000 (compared to about $8000 for commercially installed systems).

The first version of this system used plastic mat style pool heating collectors installed in a horizontal format and at a not very steep tilt angle.  I've decided to change to a vertically oriented mat style pool heating collector installed at a steep tilt angle.   The advantages include an easier and cleaner installation, better cold season performance, less susceptibility to summer overheating, and more flexibility in trying a vented glazing system to increase winter performance without overheating.

The new collector

The new collector is a single 4 by 10 ft pool heating collector mounted off my existing Solar Shed.  The vertical mount appears to be more secure and less subject to sags and folds -- it basically hangs from the upper manifold with straps to secure it from winds.  Its easy to install and appears to be quite secure.
More collector area could be provided by going with a 4 by 12 collector and/or adding a 2nd collector.

The same Softank that was used on version 1 is retained.

The plot below shows one sunny days performance.

Sunny day performance

On this sunny October day, the collector heated the 132 gallons of water from 83F to 110F.  It was mostly sunny with an ambient temperature of about 70F -- so, this is quite nice performance.

For later in the season when ambient temperatures are lower, I intend to try some form of vented glazing to see if the winter performance can be improved over that of an unglazed collector -- stay tuned.

All the details on the build and performance to date...

If you have any ideas for improving this design, please let me know.

Gary

New DIY Solar Water Heating Kit from AmericanSolarTechnics

Tom Gocze from AmericanSolarTechnics has come out with a kit for a solar domestic water heating system that is designed from the ground up for DIYers.  

The 4 collectors.

The kit uses four small collectors, each of which is 4 by 4 ft and weighs only about 20 lbs.  The collectors hook up in series for easier plumbing connections.  The light weight, manageable size, and easier plumbing connections make for an easier DIY installation.

The collector absorbers are copper tubes with aluminium fins, and the collectors are glazed with twinwall polycarbonate.

The storage tank is the SofTank, which AmericanSolarTechnics has been selling for some time.  The tank capacity is about 200 gallons.  I have one of these tanks and I like it.  It is a unique design that uses an outer fabric sleeve to bear the water pressure loads.  Inside the sleeve are several layers of polyiso foam board insulation, and inside the insulation is a high temperature liner that contains the hot water.

The SofTank

Copper pipe coil heat exchangers transfer heat to the tank from the collectors, and heat your domestic water using heat stored in the tank.  Your current hot water heater acts as the backup heater when solar is not available.

Tom has felt for a long time that solar water heating systems are too expensive -- something I strongly agree with.  This kit is his effort to bring the price down to a reasonable level that offers a good payback.  The kit is $2750 -- this compares with typical commercial systems costing around $8000.

While the system is not yet SRCC certified, this is in the plans.

The AmericanSolarTechnics DIY Solar water heating system...

A listing of solar water heating kits at Build-It-Solar...

Gary

DIY Insulating Window or Door Shutters Using Astrofoil Reflective Insulation

Bruce has worked out a DIY thermal shutter design that uses Astrofoil to provide a high R value, easily installed thermal shutter for windows or doors.

Astrofoil is similar to Reflectex, but is stiffer and holds it shape better for thermal shutters.  Both products are basically polyethylene bubble sheet with a reflective layer on each side.  While the bubble sheet is not thick enough to provide a lot of R value, the two reflective layers and the air films on each side of the foil makes for a good R value thermal shade.

Astrofoil thermal shutters in the open position.

Same shutter closed for the night.

The Astrofoil can be used with or without a frame.  The pictures above show the very nice looking DIY wood frames with Astrofoil inserts, and the picture below shows Astrofoil without a frame placed in a window.  The frameless version is made by just cutting the Astrofoil a little larger than the window frame opening and pushing it into place.

The 5 minute Astrofoil shutter -- cut it out and push it into place.

All the details here...

Gary

DIY Solar Water Heating System in Southeastern Pennsylvania

This is a nicely done $1K style solar domestic water heating system built by Matt in Pennsylvania.

Matt's two copper/aluminum collectors on the roof.

The system uses two homemade collectors in which the absorber is made from copper tube risers with black aluminium fins to transfer heat into the riser tubes.  The collector is glazed with polycarbonate sunspace glazing, which holds up well to high temperatures harsh weather.  These are relatively easy to build and all the materials are available at the local hardware.

Laying out the collectors in the living room - not generally a spouse approved method.

One of the unique features of Matt's build is the use of a copper pipe coil for the heat exchanger.  Most of the $1K designs have used a coil of PEX for this purpose.  This heat exchanger is used to heat the incoming cold water in a single pass before it goes to the regular hot water heater.  Since it only gets the single pass to do the heating, it has to be an efficient heat exchanger.   The copper coil appears to be doing well -- more of the details on that will be added when Matt finishes some tests he is running.

The coil of copper heat exchanger inside the 250 gallon heat storage tank.

All the details on Matt's DIY solar water heating system...

Gary

Craigslist to promote causes or ideas

It looks like Craigslist can be used as a free way to promote causes or ideas.

I found this link: http://reno.craigslist.org/grd/3258942054.html in my traffic report the last few days -- it is basically a person in Reno who built the solar heated stock tank, and is using Craigslist to tell people it works fine and that he recommends.

This seems like a pretty good way to get the word out on good projects or good ideas?

Don't know what the Craigslist folks think of using this approach?

Gary

Increasing AC Efficiency Using Evaporative Cooling of Condenser Coil

This project from Chad adds an evaporative cooler around the outside of a conventional outside AC condenser coil.  The evaporation of the water in the cooler pads cools the air going into the condenser coil and substantially increases both the capacity and efficiency of the AC unit.

Evaporative cooler on condenser coil.

Chad provides a lot of detail on how to build the unit.  All of the parts are readily obtained locally or online.

The picture above shows the screen enclosure for the evaporator pads.  The pads fit between the two screens and are the same type of material as used in regular evaporative coolers.

The pump and all the valves fit in a 5 gallon bucket that sits next to the condenser coil unit.

An advantage of this method compared to just spraying water directly on the condenser coil is that mineral deposits do not build up on the coil.

All the details on building this system here...

Gary

New Home Page with "Web Walk"

Build-It-Solar has a new home page as of this morning....

About the only significant change is that the "New Content" area has been expanded to include a "Web Walk" section that gives some news items that might be of interest to people who are into renewable energy and building projects. The new page layout also gives a more complete overview of all the subject areas that Build-It-Solar covers.

I added the "News" section because I spend some time on most days looking at quite a few sites for new projects or project ideas, and I thought I might as well pass along other things of interest that I run across.
I plan to add a batch of "News" links every few days -- these sections are labeled "Web Walk" in the "New Projects" column on the home page.

If the new home page gives you any problems, or you have any suggestions, please let me know.

Gary

Prince Edward Island Passive Solar Bermed ICF Home on a Budget

This is Tracey's very nice home on Prince Edward Island, CA.   Its a passive solar home that uses earth berming on the winter wind sides, and uses ICF (Insulated Concrete Forms) for the walls.

The home has large south facing passive solar gain triple glazed windows for winter heat gain, along with roof overhangs that shade the house from unwanted summer heat gain.

South windows provide lots of solar gain to the heat storing floor.

The long east-west layout of the house and use of Solatubes to provide lighting in some areas makes for a very pleasant and bright interior.

The 1285 sqft floor plan.

Probably the most amazing thing is that the home was built on a very manageable budget.

Tracey provides lots of detail on the house including a book on the whole process of designing and building a  very efficient solar home within a budget.

All the details here...

Gary

Home Heat Loss Calculator -- Updates

Our Home Heat Loss Calculator gets used several hundred times a day, so I thought it would be good to make a few small updates.

The calculator lets you estimate the heat loss, yearly energy use, fuel cost, and greenhouse gas emissions that result from heating your house.  It estimates losses for ceilings, walls, windows, and floors and losses due to  air infiltration.  Its easy to use, and some examples are provided to get you started.

Probably its biggest value is giving you some idea where the major heat losses are in your home, which is the first step in identifying which areas will give the most bang-for-the-buck for improvements.  It also lets you try various improvements and see the resulting saving in dollars and CO2.

So, I cleaned up the forms, added a plot that shows at a glance how the heat loss from ceilings, walls, ... compare to each other, added some printing pagination, ...

The new plot

If you use the calculator now, be reassured that no algorithms have been harmed in this update -- it gives the same answers it always has.  The one small number change is that CO2 emissions for electric fuel were lowered from 2.2 lbs/KWH (typical of coal generators) to 1.5 lbs (average US generation).

Some parts of the calculator:
The inputs look like this -- basically define your climate, pick a heating fuel, and enter Rvalue and area for ceilings, walls, ...    Mercifully, there is only one page of inputs to fill in.

You just enter your numbers in the blue boxes.

The summary output looks like this -- yearly energy, cost, and CO2 for your house as well as coldest temperature hourly loss rate.

This is a simple calculator -- it uses the usual Loss = (Area)*(deltaT)/Rvalue for each component.  It uses Heating Degree Days for your climate to estimate yearly losses.  There are fancier calculators available that give more details and probably more accuracy, but this one is fast and easy to use and appears to do pretty well -- and its FREE :)

Give the Home Heat Loss Calculator a try ...

If you have any thoughts on improvements, let me know.

Gary

Using Your Lawn Sprinkling Water to Cool the House

This is a unique way of providing some free space cooling for your house.

Rick runs the water that he is using for lawn watering through a heat exchanger first and extracts some "coolth" from it before it goes out to the yard.

Rick's current test setup.

His current test setup uses a 20 by 20 inch water to air heat exchanger with a fan that blows air through the heat exchanger to cool it.  In this current test setup, it cools the airstream about 10F and provides about 5000 BTU/hr of cooling -- about a half ton of cooling.

The energy use is very low -- the COP appears to be about 29 (SEER 125!).

Side of HX with water connections.

All the details on lawn water for cooling here...

Thanks very much to Rick for sending this in.

Gary

Calling all Sunspace Owners

I think that home attached sunspaces may be the most cost effective and sensible approach to adding solar to your house -- attached sunspaces offer:

• Space heating for the house 
• Additional living space that can be very pleasant
• A place to grow plants
• A place to hang the laundry for solar drying
• A good place to locate a solar water heater

While direct gain to the house through south facing windows can be an effective solar heating scheme, the direct gain approach has the not so good feature of quite a bit of heat loss on cloudy days and at night through the large windows.  Sunspaces allow you to harvest the same heat through their large, south facing glazing, but the susnpace can be closed off from the house at night or on cloudy days to avoid the big glazing heat losss.

A nice sunspace

Compared to traditional active solar space heating (with collectors, tanks, pumps, ...) sunspaces can be better looking and more cost effective (when you consider all of the benefits).

Doug's sunspace

For space heating, low thermal mass sunspaces collect heat quite efficiently, and it is relatively easy to transfer this heat to the house.  A good writeup on the low thermal mass sunspace design...

While having a sunspace to hang laundry in bad winter weather may seem like a small thing, clothes dryers are are the largest single electricity use in many homes -- on average about 900 KWH a year!  Even more when you consider that the dryer is pulling in cold outside air as it vents its hot air outside.  The sunspace gives you a good, sheltered, efficient place to dry clothes.

Sunspaces make a good, protected enviroment to add a solar water heater to -- the water heater will be more efficient because it does not see outside temperatures, and may need less or no freeze protection.

I've got a section on Sunspaces, but it has few examples of good, attached sunspaces used as described above.

Sooooooooooooooo, I would REALLY like to hear from folks with sunspaces -- how well do they work for you?  What's good?  What's bad?  What do you consider good design features?  

A writeup on your sunspace with lots of pictures would make my whole week!

Nick's multi-story solar space heating sun space

Or, if you have some thoughts, experiences, or questions on sunspaces, how about passing them on in a Comment below.

Gary

Comparing the Performance of Two DIY Solar Water Heating Collectors -- CPVC vs Copper

Scott Davis has come up with an innovative and simple design for a solar water heating collector that uses CPVC pipes for the risers -- its easy to build and performs well.

Scott and his prototype CPVC collector.

The collector uses closely spaced CPVC riser pipes which are silicone bonded to a flat aluminum absorber sheet.    This makes for and easy and fast build.

I did a side by side performance test of Scott's design compared to the established DIY collector design that uses copper riser tubes spaced about 6 inches apart with thicker grooved aluminum fins to transfer heat into the riser tubes.  In this test, the CPVC design performed within 5% of the copper/alum collector, which I think is very good.

The side by side test of the two collectors.

There are a number of pluses and minus associated with the CPVC design compared to the copper/alum design -- things like cost, ease of build, performance, durability, and tolerance for stagnation temperatures are all important.  Which design works out best will depend on your situation -- I've tried to provide a little data on how the collectors compare in all these areas.  

I would be most interested in hearing your thoughts on the comparison and which collector you think would work out for your situation.

Full details on the performance and stagnation tests, construction, IR pictures, etc. for the two collectors...

Closer view of the test CPVC Collector.

IR image of the CPVC collector in operation

If you go ahead and build a CPVC collector, please let me know how it works out for you.

Gary

A New Heliostat for an Innovative New Application

There is an interesting new heliostat being offered for a low enough price to be of interest for building home systems.  The heliostat is made by Light Manufacturing Heliostats.

The heliostat has an area of 2.3 sm (25 sqft) .  The mirror is a stretched, reflectorized film to keep the cost and weight down.  Prices from about $1300.

Details on the Light Manufacturing Heliostat here....

The same company offers a unique application that uses their heliostats to provide heat for rotational molding of plastic parts (like large water tanks).  This solar thermal rotational molding system appears to be simple and cost effective, and (to me) represents some truly innovative thinking in bringing solar to a large industrial processes in a very energy efficient and cost effective way.

Diagram of solar thermal rotational molding system.

In the system, multiple heliostats focus their beams on the mold to provide the large amount of heat needed for the process.  The heliostats can support multiple molds by simply refocusing the heliostat beams on mold as needed.

The first video on this page provides a rundown on how the heliostat heated rotational molding setup works...



Heliostats can be put to many innovative uses -- I've assembled a few of them here...

Be sure to look at this one at the link above:
"ROME (Reuters) - A village in the Italian Alps is finally basking in winter sunlight thanks to a giant mirror installed on a mountain top to reflect the sun's rays into the main square."


Gary

Making Good Use of Mountain Pine Beetle Killed Trees

This is a good and interesting video from Peter Brown about a local Bozeman, MT company that is salvaging trees killed by the Mountain Pine Beetle.

Distinctive blue coloring of beetle killed pine.

It turns out that the fungus that the beetle infects the pines with leaves a blue stain in the wood  that makes for very attractive color patterns on the boards when sawed by an experienced sawyer.

The beetle killed wood's structural properties are unaffected by the beetle infection, and the wood can be used for a wide variety of purposes.  The blue staining gives it a distinctive look that has made it popular for furniture and doors.

A great example of making good use of local materials that would otherwise go to waste.

Neil Wilbert of Beetle Kill Boards with his portable saw mill.

Makes very nice furniture.

See the story  on Peter's Video Blog...



Gary