PVC wouldn't work well enough.  The reason the cans work so well (as do down spouts and other similar items though the best I hear is a screen) is that the cans are aluminum and transfer heat very very quickly.  In just a few minutes one of these heaters can crank out full power.  It's amazing from what I've seen but there are other options (like I said, I think some of the screen models are even better) out there for those who can't get cans.

Got out to the cabin yesterday for a quick trip to remove the bad part on the tractor and just make sure all was well still.  It was 2F out and I couldn't stay but I plan to be back soon!

What a great picture!  All that's needed is a horse-drawn sleigh

Amen brother!  Amen

Finally for to building the box for this solar heater


I used some pine stock I had in the garage and glued two 1x's together (one with about 3/4" smaller width to accommodate the plywood (OSB actually) backing and poly-carbonate glazing) then mounted the backing on them.


Stapled and screwed and glued -- ya a little overkill but that's me


I wasn't kidding 


Ready for insulation!


But first I used some old silicone to seal the corners


Next I used liquid nails for foam board


And glued down the foam board (1") insulation after trimming it to fit.


A little weight to ensure it stays glued


Clamping the side insulation in with a backer board -- worked great


Working out the headers


Airflow needs to be pretty good so I drilled extra holes in the support


Shaping up!


Gotta make 13 more tubes, paint the box and the tubes and get everything assembled which will be tough since the tubes don't come out the same length -- I guess a little extra glue/silicone in 17 cans cna cause that -- which can cause some problems with assembly but I'll make it work with extra silicone

Might be a couple weeks before this is done but I'm steadily working on it now

one thing I'm thinking about is placing two strips of insulation behind the can tubes to support them -- so they can't sag.  Other than that it's pretty standard issue for one of these.

Oh and I need to install the snap switch (which tuns on the 4" DC duct fan when temps rise above 110F) and drill the 4" inlet and outlet holes.

Having had trouble getting my order in at St Lawrence Nurseries on time the last two years I finally went to The Orange Pippin and placed a small order for 3 apples (1 crab, 1 Antonovka and 1 Crimson Crisp) so I'll at least have a chance at seeing some apples at the cabin in the future!  This time, however, I will need to keep the gophers at bay!

Getting there.  You can see the box is insulated now and I've trimmed out the edges with aluminum tape


Better shot of the taping


Cans are a bit tight but should work.


Airflow should be very good   Now to get the stacks done (having some issues there lately with them breaking -- going to use some liquid nails and see how it does).

There's always the handy-man's friend ... duct tape   

Quote from: JavaMan on January 15, 2017, 02:32:37 PM
There's always the handy-man's friend ... duct tape   

Funny thing, I was thinking the aluminum tape I used around the edges would work well as a repair for the can tubes that cracked apart a bit....but bought some liquid nails I'm going try next.

Got the box painted and the 4" inlet and outlet's drilled and installed.  I set these 1 foot from opposite ends of the box so the air has to flow through the box from one side to the other in an attempt to ensure I get decent flow through all tubes.


Test fitting the tubes.  Once I have all 17 made I'll silicone them into place and paint them black with the same high temp BBQ flat black paint I used inside the box.


You can see the header and the outlet placement


Switched from silicone to liquid nails after checking that the liquid nails could take fairly high temps.  It is working a lot better than the silicone and should hold the cans well.

Up at the cabin and it's looking like more snow.  Was 23F when I got here and warmed up to maybe 25.  The inside of the cabin was slightly warmer and with both the woodstove and the heater going I've managed to get it above 60....took a few hours but I think I'm up to 65F now:) and the backup heater is back to pilot only.

Back room has stayed above freezing with the 8000btu heater turned down very low so I'm happy with that.

The bad news is that the tractor battery is completely dead and no attempt to revive it has worked.  So after 3 or 4 hours (more like 4) of trying to jump the tractor I gave up, pulled the battery which is still dead, and called it a day.  At least I replaced the kill switch, for al the good it did me!

Now, with luck and a new battery maybe I can get the tractor running again.

Batteries were at 100% when I arrived and I ran the generator for the last 4 hours to give it a good running.  I'll shut it off soon and disconnect it before going to bed so I don't have to deal with it in the AM.  Then I'm leaving again tomorrow but I may be back in a week to once again try to get the tractor running.  If not, I'll be back the 3rd with my wife to try to install the new heater on the porch.  This should be a big improvement as the batteries have been dropping to 0F or lower (the controller doesn't seem to like that and no longer reads the correct temps which is a problem I had on the first Morningstar controller I had.  It's showing temps of 249-255 again and it seems that when the batteries drop to 0F or lower this starts to happen though it took a month or two this time.

Otherwise the batteries have been holding around 24.6vdc at their lowest over the last month or two and getting to 30v daily but rarely getting a good absorption charge.  Looking at my solar production it appears I've had many days of only 2-5AH with a smattering of 10-15AH days.  Obviously this is an issue that my new panels should resolve but I can see some trees that are hiding the sun when it's this low on the horizon.  I'll have to get them down this winter as soon as the tractor is running.  Then, when the weather is good enough to get up on the roof I'll get the new panels installed and more than triple my solar capacity not to mention install the Outback charge controller which should give me some better info

I'll also have to get the batteries boxed in and the vent fan installed (I'm going to buy one from Backwoods Solar that the Outback can kick on at 28v).

Otherwise, it's getting warm in the cabin and it's good to be here -- oh, and the porch?  Awesome!  Having a nice big covered deck/porch this time of year is worth it's weight in gold!

When I arrived at the cabin it was a beautiful day!  It was also warm at 23F


Gratuitous snow pics


I'm liking the porch!


Made this from my solar logs from October to present (for some reason the controller did not have logs from May 2015 to October 2016   

This is the max voltage (blue) and min voltage (red) the batteries have seen.  Haven't seen them drop below 24v but am frankly a little surprised by the lower voltages shown as there is very little draw on them when I am not there.  Sure, I have 3 very small DC fans in the back room (computer fans) running and the 24v to 12v converter as well as the battery monitor but those shouldn't draw much power at all.....kinda scratching my head here  but suspect it's just due to the lack of solar production.

Amp Hours Daily -- this sorta tells a tale on why the batteries aren't staying charged me think   I can't wait to get the new panels up!


The real tale might be in the Absorption and Float numbers...notice float disappears late November and doesn't recover.  So I'm getting very little Absorption and no float since.  Yup, need more panels (but we all knew that )

Getting there!  Should be ready for glazing this weekend but the glazing won't be in until Monday or Tuesday.

Waiting for the liquid nails to cure so I can paint the cans   I'll paint tomorrow, today I'll finish a few minor details in the header.

The lexan is supposed to arrive the 27rd through to the 3rd of Feb so I have to wait before completing this heater.

Figuring out my snap switch and how I will get it into and perhaps out of the heater.  My intent is to be able to remove it so I can replace it with a different one if need be, or just fix it or replace it if it fails.  So, I drilled a 4 1/8" hole through the header (same size for the 4" ducts) and used the 'plug' to make this.  I've got smaller scews to mount the switch with, those were just handy


Getting the pain done!

Now you can see the snap switch installed


And it's placement in the completed box/heater (missing glazing still)


The backing on the 'plug' that the snap switch is installed on is larger than the hole (6" square).

Hi Oljarhead,
Watching your build on this solar heater. Super interested. What is the snap switch for and you mentioned a fan? I'm totally interested in all of your solar stuff too. I have an unfished thread on this site that I need to update. We got broke into during the build and got shy about posting anything. But have not had any problems since. I'm interested in the solar because we have no heat except for a wood burner. Our cabin was 20 degrees when we got there last weekend and took 5-6 hours to warm up. Wondering if a solar heater might help keep it above freezing here in northern Wisconsin.

Sorry about the break in.

The snap switch is a thermostatic control.  It is normally open until 110F then closes and stays closed until temp drops to 90F.  The idea is when the heater gets to 110F it is ready for some forced air.  It closes a circuit to the fan which is connected to a solar panel.

Once the fan is running the solar heat production will continue to rise the temp in the heater to about 150F and remain around there as long as there is direct sunlight (or close enough to it).

Sun goes down heater stops, fan stops and you wait for the sun.

In reality these heaters can provide a lot of heat but in order to actually heat a place with them you'd have to have some way to store the energy or at least prevent it from leaving.  Sure, the 8-9000btu's would warm up a small space for at least 3 to 5 hours on sunny days but the rest of the day the temps will drop.....I will do some testing to see how well this works but in my world just 10 to 20F difference is worth the effort and once the cabin is warm the heater should help to keep it there longer.

Thanks for the info. I will definitely watch your progress on this. Your plan is too keep your battery room warmer with this? Yes, I agree that a 10-20 degree swing can sure make a difference. When I got back from the woods the wife had it up to 80 on the main floor. Must have been 95 in the loft. All the snow, about a foot deep on the metal roof slid off of the west side all at once. Scared the hell out of us!

First the battery room / porch.  But if the heater works well enough to raise the temp above 70F significantly then I have a plan to install two 6" ducts with motorized baffles in the wall to the cabin that will open at 70 or so and allow the warmth in the porch to warm the cabin.  I will also build another of these to put on the south wall of the cabin to help warm it also.  My hope is that I can keep the cabin fairly warm once the fire goes out in the wood stove.  During the winter it's always on my mind when I leave at 6AM and the cabin is 70+ but it's below zero outside.  If I don't get back early to restart the woodstove the place can lose temp pretty fast.  Not real bad (it usually only loses around 7 or 8F overnight with the woodstove tamped down all the way in very cold weather but after that, with no heat going it might drop into the 50's or lower and take longer to warm when I get back).

The challenge is to keep the cabin above 65F when I am not there to keep the stove going and the little stove won't run full on for more than a few hours or tamped down all the way for more than about 7 hours.

Have you thought about passing the outgoing air through some cinder blocks inside? This may give you more of the thermal battery you are looking for.

Difficult to do at ceiling height.  if I had the room I'd consider a large water barrel to 'heat sink' the energy but no room for that either unless I remove the freezer.

Best I can do is insulate well and see how this heater does.  I bought a temp data logger to be able to see how the heat production goes with this one and what the inside temps do.

First test!  Panel was not at optimal angle and the sun began to hide behind clouds but before it went behind the clouds I saw temps rise to above 152F coming out of the top outlet.  That with outside air temps at 30F!!!

So a 120F degree rise in less than optimal conditions.


With clouds in the way I was finally able to get the logger to work and recorded the above.  Not as good as in the full sun but still plenty to warm the porch

Note:  I started the logger inside the house and took it out and placed it into the heater so the start temp was off as it hadn't cooled down to house temps before I took it back out and stuck it in the panel in hopes of recording something.

So far the logger is not making me real happy as I can't get it to start off the button unless it's connected to a PC.  I'll see if I can get it working on my linux box I use at the cabin.  If I can then I can use it to see how it performs there which is my hope.

I think I have the logger working finally!  I also saw temps of 154F before realizing the logger wasn't working.  It's an el cheapo model so I guess I can't complain but so far it appears to be recording again and I expect to have some pretty sweet data to share.

Now, I have the software working in Linux but the USB port didn't seem to see the logger when connected to the machine.  After getting some more readings I'm hoping I can solve that problem as the logger really needs a PC to make it work.  Worst case I'll take my kids unused win laptop with me to the cabin so I can get the logger recording when the panel is installed and in full sun.