Two Collectors Using Aluminum Gutter Downspout Absorbers


These are two very interesting solar air heating collectors that use aluminum gutter downspouts for the absorber. 
Scott 1' Collector:

A low profile, almost invisible collector


Scott 2's Collector:

A large collector that can be disassembled for summer


Both collectors happen to be done by Scott, but its two different Scotts :)



Scott 1's Low Profile Collector

Scott and Brad's collector uses the downspouts for the absorber, but also is a nice solution to a situation where you want to get some solar collection with little to no visual impact so as not upset the neighbors.



This is the finished low profile collector.

Its only 1 ft high and is barely visible -- its 24 ft long.


This gives an idea of the internal construction.  The rectangular tubes are aluminum gutter downspout tubes,

Air inlet and outlet at center

Air makes a 180deg turn at each end, goes
across the top, and then comes back to exit vent.


A pretty neat way to get some collection area in without being very visible at all.  Scott feels that he could have made the collector twice as high without making it much more visible, which would get the collection area up to 50 sqft.


For a full description of building the collector, how its performing, and some "what I would do differently" comments on Scott's site here...

Scott also did this collector...  and is the founder of the Yahoo Simply Solar group...


Scott 2's Bigger Downspout Collector

This is a much larger collector from Scott 2, that also uses aluminum gutter downspouts for the absorber. 




This shows the internal arrangement for the collector.


The plenum at the far end of collector

The inlet and outlet vent plenum.


Another unique feature is that the collector can be disassembled and taken for the summer.


For a more complete description, see the bottom half of this page on Scott's website...



A Couple Thoughts on these Collectors

These are a couple thoughts on the two collectors -- both of which I think show some very original thinking.

- The low profile collector idea seems pretty neat to me.  It shows that you can get some worthwhile collector area even where a larger, conventional collector might be visually objectionable. 

I think we tend to loose track of the fact that when you build a collector yourself, you can build it any shape you want to.


- These collectors offer some of the same advantages of the "beer can" collectors.  They achieve the same sort of good flow distribution and large heat transfer area as the can collectors do, but with a lot less work.


- To me, both collectors have what seem like rather long flow paths compared to most air heating collectors.  It seems like a flow path length of 20 ft (more or less) is usually enough to get a good temperature rise, and might do so with somewhat less fan power than these longer paths?   One way to do this if the house geometry allowed it would be to have an inlet plenum on one end and and outlet plenum on the other end -- so the inlet and outlet would be on opposite ends of he collector -- along the lines of the TEA collector...


- The larger collector spaces the downspouts away from each other, and I have to wonder if this is not costing some performance.  It would be nice to know what fraction of the sun that lands between the downspout runs ends up as heat to the room vs being lost out the glazing? 
Also wonder if the collector efficiency could be improved a bit by squishing down the downspouts into a flatter but wider shape so that there was less open space between them?  Maybe run them between a couple rollers to flatten and widen them a bit?


Thanks to both Scott's for doing this work!!


Gary December 12, 2009