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Posts: 303
Reply with quote  #41 
Here's an update on recent construction -

I assembled the front screen frames.  Nothing special here - these are made from 1x2 lumber instead of the 3/8 plywood I used on the back frames.  I glued the joints and stapled across to hold it while the glue dried, then I drilled pilot holes and hammered in a 6d finishing nail into each joint:

(01) Front screen frame 01, 051118.jpg 

(02) Front screen frame 02, 051118.jpg 

The above photos show the 2 frames stacked.  Since they are stiffer, they only have a single cross-bar.

Then I made some spacer brackets to hold the frames in the collector.  These are made from two Simpson A21 angle brackets.  The 2-inch leg was cut down so the finished assembly sets screen spacing at the desired 1 3/8 inch.  The 2 pieces of each bracket are siliconed together:

(03) Screen frame bracket, 051118.jpg 

Then I set the back frames in the collector and clamped them down with the brackets.  The brackets are screwed into the wood blocks previously glued into pockets in the polyiso (back frames are painted now):

(04) Bracket holding back frame. 051118.jpg 

Here it is with all the brackets installed:

(05) All brackets, back frames, 051118.jpg 

Then I rested the front frames on top of the brackets to check for fit.  I drilled and screwed through the front frame into the bracket, and fastened each point with a sheet metal screw.  The Simpson brackets are 18 ga. so they take a screw well (think I took this picture before I added the screws):

(06) Both frames in collector, back held with brackets, 051118.jpg 

Everything fit together pretty good and tight, so I took it all back apart, because I still need to add the screen and paint.  Here's one of the back screens, stapled to the frame:

(06.5) Back screen, 051118.jpg 

Thankfully, the back frames still fit in the collector OK:

(07) Back screens loose in collector, 051118.jpg 

Here it is with the front frames resting loose on top of the back screens:

(08) Back screens + front frames in collector, 051118.jpg 

 I added a piece of 3/4 square dowel to the edge of the lower front frame to close up (most of) the gap at the end.  I will cover this with a strip of flashing after I put the front screens on:

(09) Front screen spacer, 051218.jpg 

That's it for now.  Next is to finish the front screens and paint everything.  Thinking I may wait to permanently install the screen frames until I get the glazing attachment worked out so it doesn't get too much dust in there.


Posts: 149
Reply with quote  #42 
Looking good!  I like the fit and finish of your quality work.  I see the front screens don't cove the inflow and outflow holes...do the back screen cover the holes or the plentium area at all? Thanks for the update.  I am going to start my project as soon as things slow down a little at work.

Posts: 303
Reply with quote  #43 
Bruce,  None of the screens cover the in/out ports, at least not yet.  I still have to screw in the snap disc + bracket between the output port and the upper wall of the collector, and there isn't much area there in any case.  Also, I'm still not sure how exactly to do it.  I did include wood blocks at the top and bottom, but not in the center.  I figured I could attach a stand-off to the 12 inch wide aluminum sheet that's glued to the back.  Haven't decided either if one or 2 screens is better here; seems like you wouldn't want to block the intake or shade the snap disc either.  I'm still considering the possibilities.  Here's the block at the bottom of the intake plenum (hard to see now that it's painted):

Wood block, 051418.jpg 

This is the snap disc assembly that needs to go near the output port:

Snap disc, painted, 031418.jpg 


Posts: 303
Reply with quote  #44 
Details - time for an update before I forgot what I did.

To try to keep a smooth flow around the turnaround, I stapled some aluminum flashing 'fins' on the lower screens, both front and back.  The air, which is travelling up here, should slide off the end of the fins back onto the screens, or at least that's the theory.  Here's the back screens with the fin staped to the bottom screen:

Back flashing, 051518.jpg 

There's a matching fin on the lower front screen.  This fin is on the back side of the screen frame when it's in position (opposite of what is shown):

Front flashing, 051518.jpg 

I painted all the screens, just the side that faces out, and the edges.  Here's all the screens loose in the collector.  You can see where the fins are, although not much is visible because of the 3/4 x 3/4 strip of dowel on the top edge of the lower front screen.  Haven't decided if that dowel was even necessary; its mainly there to help support the glazing if that seems necessary:

Black fins, 052418.jpg 

I bought a piece of Palram ThermaGlass 8mm twin-wall from Griffin Greenhouse in Aurora CO.  They only had 4x12 and 4x16, so I bought a 4x12 and cut length to 8 ft. with a sharp utility knife.  Now have a 4x4 scrap for something.  Had to flip it over and cut both sides.  It was slow going, but it came out clean and straight (no plastic sawdust and no scratches).  I left the protective covering on to cut it.

While I had shade, I laid out the glazing parts - the twin-wall, gaskets, and angles:

Glazing, loose, 052518.jpg 

  The gaskets will be siliconed to the front face of the track frame (after I'm done turning the box over).  I slipped the gaskets in place loose under the glazing, then clamped the angles loosely in place, just so everything stayed put:

Glazing with angles, 052518.jpg 

Here's a close up of one of the short gaskets.  It's made of 1 inch x 1/8 inch synthetic felt (300 F rated, McMaster-Carr p/n 88085K71), wrapped in high-temperature aluminum foil tape (McMaster-Carr p/n 7631A32).  Besides the perimeter of the frame, there will be gaskets for the center divider, the ends of both front screens near the ducts, and the top of the lower front screen at the turnaround.  Hopefully the glazing will sit on a continuous flat gasket surface everywhere anything meets the glazing:

Gasket 2, 052518.jpg 

I had previously drawn a line through each threaded connection (T-nut embedded in the frame plywoood lining) on the outside of the collector.  When I clamped the angles pieces, I extended each line onto the angle.  I also pressed down lightly on the angle at each screw point and traced the bottom of the angle on the side of the main box.  Then I measured on the collector from this mark to the center of each hole, and transferred the measurements to the angle piece at corresponding locations to define the drill points.  Checked everything twice, then drilled clearance holes in the angles.  I was able to put in all the screws, so the only thing that man need fine tuning at final assembly is the height of the holes.  I can elongate with a small file if necessary.  This was all  sort of time-consuming, and a hard way to do it.  The angles (and glazing) will be held on with stainless 8-32 screws.

Here's one of the end angle pieces with holes drilled.  I also had to relieve out a pocket for the handle (see above photo).  These were slow too.  I drilled a lot of small holes close together, then filed out all the scrap until it fit and looked right.  The handle has enough clearance even with no gasket, so I'm pretty sure it won't interfere with the angle hold-down at final assembly.  If I didn't mention already, the angle pieces are made from ripped stud-track:

Angle, 052918.jpg 

Lastly, I attached the snap disc and bracket, with the 22 ga. wires going through the back wall and into a plastic J-box.  The wiring is low-voltage, since the snap disc only controls the 24VAC coil on the fan relay:

Snap disc installed, 052918.jpg  Wiring box, 052918.jpg 

I'll paint the screw heads next time I use the black spray paint.  That will likely be on the 1 3/8 inch x 20 inch flashing strips I still need to make.  These will round off the corners in the turnaround, between the screen layers, and be held with the same screws that hold the screen brackets (see earlier post).  I'm also waiting to permanently install the screens until I'm done turning the box over.

I really am going to turn the box over, to paint the outside.  Got some gloss white Rustoleum enamel and some Rustoleum primer (for 'clean' work).  Thought about flat white finish instead of gloss, bit I suspect it may rub off easier.  Either way it should blend in the white silicone if there are any 'holidays'.  That's next.  After painting, it's put it all together for good - screens, gaskets, glazing.  Then I need to figure out how to keep the glazing flat when the fan is pressurizing everything, and work out details for the wall-mount (mostly re-using the old mount for the slanted 2-screen, with some additional hardware.  After that, connect the wiring and test.

I'm looking for some type of lightweight temporary cover to put over the glazing so it doesn't overheat while I'm mounting it on the wall, and hooking up the air ducts, but before I can get air moving.  Wondering if a shade-cloth curtain is shade enough for when the fan isn't running, while being easy to move out of the way easily while I'm blowing air through the collector at heating temperatures to clear it out.  I sure don't want to let this thing stagnate, especially while it's still green.  Been there for that.  Probably connect the input port to my existing blower inside and just dump the collector output outside or into the back room during test.  I'll keep screen coverings over any open ports, and try to keep my 14 x 14 air filter box in the path during testing.  I need to get a new filter for next winter anyway.

That's it for now.


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Posts: 542
Reply with quote  #45 

Looking good. Those metal fins did have me confused at first until I figured out the orientation. It makes sense now.

I did try shade cloth with mine but I felt it was still getting too hot. It was black though, so maybe a lighter color would work. Something solid and light colored would probably work better.

Mine gets up to 100 at times with the painted poly but hey, it gets hotter than that in Arizona.

Bert K.


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Posts: 2,461
Reply with quote  #46 

I am glad someone other than myself is actually thinking about solar heating this time of year. And yet, here you are finishing up what looks like a great new heater! It will have plenty of time to air out and unless you get some wild idea for ANOTHER new heater, you should be ahead of the game this fall. 

Here in Minneapolis, we just finished a streak of 6 straight days of 90˚+ days...in MAY! Last streak like this was in August of 2013, when I was residing my house. Check out the weather station readings half a block from my house this past Sunday:

It is only the second time Minneapolis has reached 100˚F in May, and the last time was back in the dust bowl year 1934. This has been a really odd spring, I say that because 6 weeks ago we had 20" of snow and now the heat and rain. We pretty much skipped spring altogether!

Anyway, your heater looks really clean and professionally built. I look forward to the performance numbers this winter!

I can't wait to start my new ZP, but being that it has to be built outside due to the size. I started about a week too late last fall and the temps cooled off too much to continue. This year, I will start my build earlier, but then again, I say that every year...

Greg in MN

PS:Take a look at large rolls of paper at the big box/hardware store for your temporary cover. It's often used by contractors to lay down on flooring to protect from damage. 


Posts: 303
Reply with quote  #47 
Yeah, I think climate change is picking up speed.  We need more solar!

I see the large paper rolls on Home Depot's site.  That should work OK for installation, and it looks like some useful stuff to have around.  I might eventually need something more durable that can get wet for a long term 'off-season' cover.  Plywood seems like overkill; that's what I used on the 2x16.

I'm thinking of painting some of the gaskets black - the ones that aren't hidden under the angle pieces around the perimeter.  They may end up mostly covered anyway, depending on what I need to do to keep the glazing from bowing out.  Guess I'll find out about that pretty soon.

I painted the outside of the box with primer, but then it got windy.  Hope to add the top coat tomorrow.

Posts: 56
Reply with quote  #48 
A word about covers. I covered my collector with a white paper base tarp normally use to ship lumber. The next year I noticed a lot of small micro scratches in the collector cover. This year I added a couple of old blankets under the tarp cover avoid any wind-wear. I have seen some tarps with soft fabric on one side but have no idea on where to find it.

My ZPDP collector is hinged and lashed under the south facing house eve and runs about 10-15 degrees over the outdoor temperature. I also installed a 140 degree snap switch in the top of the collector as a backup alarm. The inlet and outlets are covered with a fine window screen and a 8" duct fan to vent if ever needed. We sometimes get 40 to 60 MPH straight line winds in central Illinois.

Jim from IL

Posts: 116
Reply with quote  #49 
 "This year I added a couple of old blankets under the tarp cover avoid any wind-wear. I have seen some tarps with soft fabric on one side but have no idea on where to find it."
Picnic table covers have that feature. 


Posts: 303
Reply with quote  #50 
Thanks for the info about tarps, tablecloths, etc.  If I use paper, it will only be for a day or two while I am getting the collector attached to the wall mount and  connecting air ducts.  That's a good idea too about the over-temp alarm.  When I have collectors covered and sitting idle, I always cover any open ports with screen to keep out bugs, dirt, etc.

I'm still working on odds and ends - Painted the outside of the box and the glazing holds-down angles with white Rustoleum.  I changed my mind and used flat finish; thought the gloss might be a bit too stark:

Box painted white, 060118.jpg 

Angles painted white 02, 060318.jpg 

I glued on all the gaskets that go on the front screens yesterday.  Today I painted those flat black.  I wasn't originally planning to paint the gaskets at all; doing it again I would glue the gaskets on first before painting any of it and just painted it all at the same time.  It came out OK all the same:

Screen gaskets glued and painted black, 060318.jpg 

There is a third gasket on the lower front screen in the turnaround area.

I also glued on the gasket for the center divider.  Have to let the silicone cure before I paint this.  I'm spending a lot of time now waiting for glue or paint to dry.  Oh well:

Center gasket glued, 060318.jpg 

After I paint this gasket, I need to glue the gaskets to the front of the track frame.  Probably use clear silicone for these, since I don't plan to paint them afterwards.  They will be covered by the glazing angles.  After those gaskets are glued it will be time to give everything one last dusting and install the screens and glazing for real.  Guess it's time to remove the masking tape too.

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