Monday, December 7, 2009

THREE new Owner Built Solar Space Heating Systems

This has been a good week for new solar space heating systems sent in to Build-It-Solar!
Thanks very much to the Eric, Al, and Tom for describing there well designed and built systems. 
These are all large collector systems that can do significant solar heating -- lots to learn from the detailed descriptions of these systems.

The 1st is Eric's space heating and hot tub heating system that uses 300 sqft of water heating solar collectors, and has both a solar and boiler heat source.

The 2nd is Al's space heating collector that is primarily a solar air heating collector, but also has a smaller water heating capability integrated in the same collector.

The 3rd is Tom's new 330 sqft solar space heating system.  This system uses Tom's 3rd generation design for the copper tube, aluminum fin collectors.  This installment covers the design, build and install for the collectors.  The next will cover heat storage, plumbing, and controls.

See below for summaries, and the links for very detailed descriptions.

Al's Hybrid Air and Water Heating Collector
This is a very nicely done collector of about 100 sqft.  It is a space heating collector that primarily heats air that is circulated directly into the house.  But, it also has a smaller water heating capability that is used to store some heat for use during the night.

Its a nice looking collector that is well integrated with the house.

Since the collector area is about 15% of the house floor area, the collector will often generate more heat that can be immediately used on a sunny day, so it makes sense to add the limited water heating capability to store some heat for use later in the evening.

All the design and construction details from Al here...

Eric's Space Heating, Water Heating, Hot Tub Heating Solar System
This is a very nicely designed and built system from Eric -- a fellow Bozeman resident.
The system uses about 320 sqft of commercially made water heating collectors as its main heat source.  The collected solar heat is used for 1) space heating, 2) domestic water heating, and 3) hot tub heating.  The system also integrates a boiler as the secondary heat source.  


This is a pretty complicated system in that it heats floor space, a hot tub, and domestic water, and includes both a solar and boiler heat source into the same system. 
This is a difficult set of things to do, but Eric pulls it off with a pretty simple system.  Maybe the fact that he is in the HVAC business and specializes in solar system helps :)

All the details on Eric's system...

Tom's Large Solar Space Heating System
Tom's new space heating system uses 330 sqft of the aluminum fin/copper tube collector design.  This is about Tom's 3rd generation build of this type of collector, and he has a very refined design.   The collectors are mounted in a good looking common housing, and glazed with twinwall polycarbonate glazing.  Performance should be very good.


All the details on Tom's System...

Much more on Solar Space Heating Systems...



  1. While all the above are interesting, I am always excited to see tom's work. They really are all very good looking.
    Really liked seeing the better tube contact with the fins.
    Looking forward to his heating system progress/update.

  2. Matthew,
    Thanks for the nice remarks!
    I have a 400 gallon tank done and filled, and the pump and controls mostly complete. Enough that I'm making hot water every time the sun shines. I have a 200' x 1" copper heat exchanger completed too, but haven't had the time to install and plumb it yet. I'll get everyone an update as soon as I can.
    Tom Sullivan

  3. I just read about Al's system and really like the professional way it looks. Having installed a fairly large system like that on my hangar, I was interested in other "hot air" solar collectors. One question though; what is the heat collecting medium? Did you just paint the metal coating on the styrofoam?
    Very nice work!!
    Tom Sullivan

  4. Gary,
    Thanks for posting Eric's system. There are lots of good ideas in his design. Also some useful information. I was considering baseboard heaters in my basement, but wondered whether they would be effective without 180 degree water. His info validates my thoughts on them; less efficiency, but running longer and possibly more baseboard area can overcome the lower water temp.
    Great work Eric!!
    Tom Sullivan

  5. Hi Tom,
    Good to see you here.
    Here is a pdf on the the SlantFin hydronic baseboard units:
    It shows output down to water temps of 110F, and I'm sure it puts out some heat below that.
    I think its still 100% efficient at these lower temps -- that is, none of the heat is wasted -- it just takes more time to extract at given amount of heat from storage. I think the only waste is more pump time, and even that energy ends up as heat in the garage.

  6. Thanks Tom. I just signed up.
    Actually the Absorber is typical steel roofing 12ft long - three pieces on top of each other. I painted the front side with the high-temp flat black paint. I do not paint the insulation boards. Gary added another picture to show the steel roofing installation in place. -Thanks

  7. I too like the look of Al's system, but why does it need back insulation, if it's over an insulated house wall?
    It would seem more economical to integrate it into a house wall, behind something like Dynaglas "solar siding," a corrugated polycarbonate greenhouse roofing product that comes in 4'-wide sheets.
    A higher temp Barra system with natural airflow might have twinwall glazing or 2 layers of HP92W polycarbonate film inflated with argon.


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