Robbie said:The good news is my building is well insulated - 2x6 walls and roof with fiberglass batting, good-sealing and insulated doors. The car doors are not roll up style, they swing out like French doors and are similarly built about 6 inches thick with insulation. I did that because it's more shop and less parking. I don't move cars in and out frequently.
You're well on your way to making a solar collector work with that base to start from.
Robbie said:Or this:
https://swmi.craigslist.org/mat/d/large-tempered-glass-panels/6710586017.html
There's the mother lode.
The problem with used materials is the finished product doesn't look nearly as uniform. I do need this to look neat and trim for various reasons.
How much more efficient is dual pane glass over twin wall polycarbonate like for green houses? For $600 or so it looks like I can get 30x8 twin wall polycarbonate shipped to me brand new.
I imagine the poly panels being much easier to form and work with, as well as being WAY lighter to lift and mount and leave hanging off the side of the building. Not to mention I think they would be more resistant to an errant rock from the lawnmower or backyard baseball.
Those glass panels would look fine, especially once they're backed by black screening, but your other points are valid and would swing it for me. I don't know what the glass weighs, but it would need a significant structure across the bottom for it to sit on. It wouldn't be easy to change the size, and just retrieving them has a cost.
Robbie said:Interesting point re: sunshine days.
According to a quick Google, this site: https://www.currentresults.com/Weather/Illinois/average-sunshine-april.php
Shows January through April in Chicago averages about 50% of the time between sunrise and sunset the sun reaches the ground. December is a little less and November is a lot less (38%).
The good news is my building is well insulated - 2x6 walls and roof with fiberglass batting, good-sealing and insulated doors. The car doors are not roll up style, they swing out like French doors and are similarly built about 6 inches thick with insulation. I did that because it's more shop and less parking. I don't move cars in and out frequently.
A very quick estimation on that site shows the Detroit area gets about 30% sun during the heating season. Seems about right.
Looks great, man! Do it!
There is a lot of free heat just waiting to be collected. I'm constantly surprised how frequently my solar heater will be running on some miserable cold cloudy day. You really don't need a painfully bright sunny day to make good heat.
One of the big benefits of constant low-level heating is that your garage and slab will warm up and stay warm through the ups and downs. Like a big heat battery. And you're already well insulated.
Robbie said:The car doors are not roll up style, they swing out like French doors and are similarly built about 6 inches thick with insulation. I did that because it's more shop and less parking. I don't move cars in and out frequently.
Do you have any pictures of the doors and how they secure? I am interested in trying something like this on my garage.
In reply to TVR Scott :
It was your thread that inspired me!
EvanB said:Robbie said:The car doors are not roll up style, they swing out like French doors and are similarly built about 6 inches thick with insulation. I did that because it's more shop and less parking. I don't move cars in and out frequently.
Do you have any pictures of the doors and how they secure? I am interested in trying something like this on my garage.
I'll grab some. It's super simple, but the doors are heavy! I'm considering doubling up the hinges.
So here's a question, talking with my buddy last night (who is a master's degree holding civil engineer in HVAC systems), he suggested a flat white paint on the walls under the panel to reflect (in a diffused way) the light that happens to miss the screens on the way in, so that it could hit the screens and heat them up more before reflecting out.
So, since I will have to remove my vinyl siding to add this to the wall, and I have house wrap underneath the vinyl, can (should) I paint the house wrap directly or should I remove the house wrap and paint the wood?
This is very cool. I have a perfect South wall on my garage and I live in the desert with a fair amount of sun through the winter. My concern is, what do you do about it in the summer? How do I keep the heat out? Even with the vents closed on top, it's a big hotbox on the side of the garage warming it through conduction.
Robbie said:In reply to TVR Scott :
It was your thread that inspired me!
Glad to hear it!!
I wanted to go thermosyphon but my garage wall isn't idea for it. My system is a big compromise, but it was cheap and fun to build, and makes heat.
For the inside of your collector, I'd go flat black top to bottom. Just suck all that heat in and get your air moving.
Petrolburner said:This is very cool. I have a perfect South wall on my garage and I live in the desert with a fair amount of sun through the winter. My concern is, what do you do about it in the summer? How do I keep the heat out? Even with the vents closed on top, it's a big hotbox on the side of the garage warming it through conduction.
Yeah, these panels do get crazy hot in the summer. The simplest solution is to just cover it. A piece of white coroplast would be the easiest. You could do painted plywood too.
That is a benefit of vertical panels - the summer sun isn't nearly as direct on them.
That said, it might be nice to be able to close your inside vents and even open an outside vent to let hot air escape.
TVR Scott said:Petrolburner said:This is very cool. I have a perfect South wall on my garage and I live in the desert with a fair amount of sun through the winter. My concern is, what do you do about it in the summer? How do I keep the heat out? Even with the vents closed on top, it's a big hotbox on the side of the garage warming it through conduction.
Yeah, these panels do get crazy hot in the summer. The simplest solution is to just cover it. A piece of white coroplast would be the easiest. You could do painted plywood too.
That is a benefit of vertical panels - the summer sun isn't nearly as direct on them.
That said, it might be nice to be able to close your inside vents and even open an outside vent to let hot air escape.
Yeah, good news for me is that when the leaves fill out there will be mostly shade back there (and the long eave of the garage roof when the sun is high). I think the best option is to cover them up, but maybe you could make the glazing removable so the heaters don't get much warmer than ambient.
I don't want to 'vent' my solar collectors to the outside for fear of creating an air leak in the winter and significantly decreasing their effectiveness. So I probably will go with trying to plug the holes and cover up the collectors. But I have also seen some neat ideas for using the collectors as 'solar chimneys' in the summer. Basically you duct air from the top of your conditioned space into the bottom of the collector and then vent the top of the collector outside. That way the super-heated air is moving up and out, but it is also sucking hot air out from the hottest part of your building. Apparently a solar chimney is a common and effective solution in places like the middle east.
My problem with the solar chimney is that I want to vent hot air (and suck in outside air) from my space at night when the outside air is coolest, not during the day when for most of the day when the inside air is actually cooler than the outside air. I don't think it gets warmer inside my garage until about 2-3 pm most summer days. That would be heavily insulation and climate dependent though.
I wouldn’t paint the house wrap. It will melt and shrink when exposed to heat, and eventually degrade exposed to sunlight.
In reply to SVreX :
10-4, I will plan to remove the house wrap that is under the solar collectors.
ok, so I think I have a good design and have priced out just about everything I'll need:
Total of all that is $636. Plus tax and other misc materials that I already probably have here like paint, screws, lag bolts, etc I bet it will be all in around $700.
IF the collector does as well as the guy's in the article (he says his does about 38 kWh on a sunny day, and mine will be 20% larger), then that would save me about $100/month vs running electric heaters. Now of course I wouldn't be running the electric heaters if I wasn't out in the shop, so it's not exactly even, but kinda cool that these could produce $100 worth of heat each winter month.
Question - what goes underneath a window to capture or cover the top of the vinyl siding (where the nails are)?
The slightly less quantifiable benefit will be the higher average temp everyday. That way when you do go out there to work you're not warming it up from such a low temp and all the items in your shop are warmer to touch.
In reply to Robbie :
Under a window you use J channel.
Petrolburner said:The slightly less quantifiable benefit will be the higher average temp everyday. That way when you do go out there to work you're not warming it up from such a low temp and all the items in your shop are warmer to touch.
Yes, for sure. And I think with the size of the thermal mass of a shop, even though the benefit isn't as easily quantified, the benefit will be huge.
but, to measure, simply take a few air temp readings, then turn on electric heaters with a thermostat set 10 degrees above starting air temp. When the electric heaters first turn off (ie air temp went up 10 degrees), measure some surface temperatures. As the heater starts cycling on and off with the thermostat, record how long (I'm sure it would likely take many hours or even days) it takes for the surface temperatures to come up to the same as the air temp. That would give you an idea of how long your shop would stay warm if the temp outside were to drop 10 degrees. If you recorded the on time of the heaters it would give you a really good estimate of how much thermal mass you have.
In reply to dculberson :
hmm, yeah, I thought that, except my window will be 24 ft wide. So I can't just bridge the gap with a long span of siding. I wonder if I need to do something to hold them up or if the 'snap' into the below siding would be enough to hold pieces that are essentially unfastened otherwise.
I might be misunderstanding you.. I notice you already knew about J channel, sorry. ;-) But yes the snap to the siding below, or the starter strip, is quite strong and will hold onto the piece of siding that goes up into the J channel just fine. As long as you get it fully snapped, anything that's strong enough to un-snap it will be causing all sorts of other mayhem so a loose piece of siding would not be the biggest worry. In my opinion, of course.
Well, I decided to go all in since the weather is so mild right now. Better take advantage when it is warm out.
I'll post up some pictures later but I got a good start today.
EvanB said:Robbie said:The car doors are not roll up style, they swing out like French doors and are similarly built about 6 inches thick with insulation. I did that because it's more shop and less parking. I don't move cars in and out frequently.
Do you have any pictures of the doors and how they secure? I am interested in trying something like this on my garage.
Sorry for the long wait, here you go!
Ok, here was my progress yesterday:
Start by taking down the existing siding
It's just a lot of nail pulling, but it's easy as the nails are left loose so the vinyl can shift with expansion and contraction.
Next cut the building wrap for the collector:
Frame the collectors with 2x6 and attach to wall
And then cover everything back up temporarily as rain is in the forecast.
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