Sunday, October 28, 2012

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.


Tuesday, October 23, 2012

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.


Wednesday, October 10, 2012

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.


Tuesday, October 2, 2012

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...

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