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Posts: 565
Reply with quote  #11 
I'll post some updates later.  I just got back from a vacation.

The fans are from ebay.  I checked and the particular model I got is not available any more.  Mine are 113cfm, 5.91mm static pressure and were $9.99.  I used 3 to start with and if that is too much, I will drop down to 2.   Now this seller is carrying a 124cfm model.  I chose the Zaward brand (also sold as Globe Fan).  The seller used to have a video showing a noise comparison with another similar fan and this brand was quieter.  They are ball bearing fans which are supposed to last longer, handle heat better, and work better at angles than sleeve bearing fans.  On ebay the seller is mynewfan and he sells a lot of fans.  The label for this brand looks like this:
Fan Label.JPG 

On my first collectors I used Scythe Ultra Kaze fans (sleeve bearing), but after a few years I can tell they are going to wear out.  I don't know if the new fans will last longer.  Time will tell.  Whatever fan you choose, it is a good idea to confirm the specs advertised by a seller on the manufacturers web site.  For the Zayward fan it is zayward.com or globefan.com.

Tube type collectors are fine horizontally.  Several people have done them with downspouts.  Screen collectors are also OK horizontally.

I power the fans with a DC adapter.  This one is 2.5A and has a voltage switch I can use to slow the fans down (normally just leave it on the 12V setting though).  http://www.menards.com/main/electrical/electronics/power-supply-adapters/universal-ac-to-dc-adapter/p-1508503-c-13535.htm

Feb 2016 Update: One of these adapters failed to turn on one time and the collector stagnated.  There may be something in the circuit that shut the adapter down due to the initial surge from the fan turning on.  I am using an old power supply from a desktop computer now.  Doing OK so far.

Years ago I thought about powering the fans with a PV panel, but wasn't sure what size would be required and it would take a very long time to pay back the cost.  I have always used 12V DC because I don't want to mess with having AC going outside into the collector to the snap disc.

If you decide to use the semi-rigid duct, be careful when stretching it out.  It is made from a continuous strip of aluminum that is crimped together in a spiral pattern to form the tube.  On a couple of tubes I stretched them too far and had to seal small holes that opened.  I'm hoping the rippled surface will perform better than a smooth tube or downspouts.  It was a challenge to get the valleys painted.  The shadows made it difficult to see what was painted and what needed more.

Also, note that due to the plenums building a tube collector is more work than a screen collector.

Kevin H


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Posts: 2,925
Reply with quote  #12 
The computer fans are nice in that they're reasonably priced and a standard size.  If you need to change 'em, no big deal.
Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay

Posts: 2
Reply with quote  #13 

Thank you for your information.

The specs on the newer 124 cfm fan are:

The specifications include;

  1. Voltage, 12VDC
  2. Range, 6 to 13V
  3. Current, .52 Amps
  4. Speed, 2800 RPM at rated voltage and zero pressure
  5. Flow (Max), 124 CFM at
  6. Pressure Rise (Max), 0.28 inH2O

    Couldn't two fans be powered by this 1.5 watt PV panel?:
    panel specs: http://manuals.harborfreight.com/manuals/68000-68999/68692.pdf
    Probably a good idea to test the output voltage to make sure its steady and not variable.

    Mynewfan also has an AC speed controller for that fan:
    That could regulate the fan speeds if needed, then I would need a thermal switch or thermostat.

    How do you regulate your fans?



Posts: 565
Reply with quote  #14 
It would take a bigger PV panel to power two of those fans:  0.52A x 2 x 12V = 11.48W.  PV panels are rated under certain conditions including a 1000 watts per square meter solar irradiance.  The actual solar irradiance at your location will be lower and changes during the course of the day (there are sites where you can check this), so the panel will need to rated higher than 11.48W.  If the panel is undersized for the load, the voltage will drop off fast.  It may help to have a battery in the circuit.  There would be some charging while the collector is not running.  Someone with more experience with PV may be able to help you determine a minimum panel size.

I just use a snap disc.  In my experience the amount of run time lost at the start of the day / end of the day is minimal.  There are other discussions here on Simply Solar on various ways to regulate the fan.

Kevin H

Posts: 565
Reply with quote  #15 
Some nights in the 50's have reminded me that it is time to get busy and finish these collectors.

The inserts for the window are painted and covered with 1/2" polyiso.  Next I need to figure out the dampers.  I am going to try a shallow square box on the output with a light door, possibly Styrofoam.  When not running, the door would be held shut with a magnet.  By making the magnet distance adjustable, I'm hoping it will be strong enough to keep it closed when not running, but still allow the door to open from the air pressure when running.  Not sure yet on the air intake side.  I've seen all of the ideas on Simply Solar.
Window Insert.jpg 

This is the top end plenum for the in/out ducts.  The snap disc is glued and bolted to the top, inside of one of the hot side tubes.  The wire for the fans goes down the bottom of a tube on the cool side (left).  Having the ducts come straight out the top means the plenum has to be taller.
Duct End.jpg 

This is the board that holds 6" ducts.  I already have the plenum sealed with polyiso and will use this board as the template to cut the openings in the polyiso.  I used duct elbows since they will need to angle slightly toward the center to line up with the window.
Duct Board.jpg 
- Cut duct openings in polyios.
- Mount in/out duct elbows.  Paint the duct board.
- Connect fans to power wire and do a test run.

The second collector is also being worked on and has made progress.  It's ready to have the turnaround end covered.  After a trip to Menards, the duct end can be finished.

Kevin H


Posts: 565
Reply with quote  #16 
A while back I did a test of airflow and it was plenty (don't remember the exact CFM, will check it again later).  I'm glad I used 3 fans instead of 2.  The U turn at the bottom adds a bit of a bottleneck.  The second collector has a slightly bigger opening at the U turn.

Today I installed the twinwall glazing.  With all of the H channels installed on the twinwall I positioned the sheet where I wanted it on the collector.  Then pilot holes for the twinwall screws are drilled.  The twinwall screws have a washer and gasket.  As each hole is drilled I put in a nail to hold everything in place as I moved around to drill the other holes.

Then the glazing was removed to clean up the shavings from drilling.  The glazing was placed back on and the nails were reinserted to get everything lined up again.  Then I ran a bead of clear silicone glue under the H channels.  One by one the nails were removed and replaced with the twinwall screw.  There is a wood 1x2 under the top lip of the stud track to accept the screws.

Glazing Installed.jpg 

Next the collector will be moved out to the garage so the steel stud track sides can be painted.  For all of the stud track painting I used a primer followed by the Rustoleum paint.

Then I need to build the wood A-frame to hold the collector.  Like my past collectors, these will be taken down after the heating season is over.

I'm finishing up the plenum ends on second collector, so it will be ready for glazing soon.

Kevin H


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Posts: 2,333
Reply with quote  #17 
Looking good Kevin-

My very first collector I screwed through the twin wall. The problem I had was lining up the hole to the top center of the 1"x6" side boards . You only have ¾" to line up and drill between the ribs. If I had thought that problem out ahead of time I would have adjusted the side boards slightly to line up be between the ribs. As it was I tried to fudge things as I was too far along in the build and ended up splitting the top of the side boards a bit and/or having to screw through the ribs which caused leak problems in the spring.

Attaching twin wall directly does help eliminates any trim or edge for snow to get caught. That build was scrapped and turned into my testing box. Live and learn...
Also, my stands were made out of PT 2x4's. While a bit heavy, they are sturdy. But leaving them exposed to the elements also warped some of the legs a little bit which makes the easel-style stands difficult to open. 


Posts: 565
Reply with quote  #18 
On my first collector that had 1x6 sides I cut a slot in 1x2 wood for the twinwall.   That was attached to the 1x6.   The slot was loose enough that the twinwall could be slid in.  It was made of a composite material sort of like Masonite and even though I had sealed it with waterproof deck stain, it still picked up moisture and gradually swelled around the screw holes.

No matter how well I plan, there are always little things that come up during the build.  For example, this time the center of the H channel where the screws go didn't end up centered in the cross bars.  I may not have fully accounted for that extra 1" of length (1/2" for each H channel).  It still worked OK, but came close to requiring trimming the twinwall a little.

I used regular 2x4's for past stands and used deck stain to protect the wood.

These will probably be my last collectors for a while.  I will have the old 4x8 screen collector for the basement, these two new 4x10 tube collectors for the main level, and the air exchanger preheater.

Kevin H

Posts: 565
Reply with quote  #19 
"Baking" the second collector today.  It has been a long time since it was painted, so I don't think there would have been any off gassing onto the glazing, but better to be safe.  Plus this will get rid of any odor from the insides of the tubes from any manufacturing residue.

I just stretch a poly sheet over it and leave openings at the top and bottom for some passive air flow.


Kevin H


Posts: 565
Reply with quote  #20 
Finally got the first collector in place today.  I just have to make the short duct sections and insulate the ducts.  Since this collector is taller, the ducting outside is a lot shorter than the old collector.  It will be running tomorrow (cloudy today).  The one to the right is an old screen collector that feeds into the basement.

 Collector 1 Set Up.jpg 

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