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-   -   Inexpensive solar garage heater (https://ecorenovator.org/forum/showthread.php?t=592)

Daox 08-10-09 08:39 AM

Inexpensive solar garage heater
 
I do a lot in my garage, and I love it. But, in the winter, it really is a pain when I have to get all bundled up and go out into the freezing garage and try to do some work. So, the solution I'd like to get some input on is how to heat the garage with solar power. It doesn't have to do a ton of heating, but it does have to be kept pretty cheap.

The first thing I was thinking of was a hot air panel. Very cheap, pretty easy to make. The down side is there is no thermal mass to them. You get what you get during the day and it is gone as soon as the sun stops hitting the panels.

The second idea is a really stripped down solar hot water collector idea. The system basically consists of two 55 gallon barrels. One outside, one inside. Get an inexpensive ac or dc pump (Gary on builditsolar.com has been using a $55 pump successfully for a year now) , a small solar panel, and maybe a DIY temperature differential controller (pretty easy to make I'd think from an arduino). The outside barrel could be enclosed in something for some insulation and freeze protection. As it heats up, it pumps the water/antifreeze solution into the barrel inside the garage. Pretty simple, and much more thermal mass. This idea could really be ramped up with a simple and nice solar collector, possibly with a small drain back system to eliminate freezing. But, this all increases cost, barrels are cheap. We'd have to see how far my budget would allow this to go.

Other ideas? I'd love to get some input.

Daox 08-10-09 09:00 AM

This is the pump Gary has used.

Swiftech MCP350 12 VDC Pump

You can pick it up on Newegg.com for $55.

Daox 08-10-09 09:47 AM

Another idea I just had. I have a used radiator laying around from a car. Surface area wise it is probably similar to a 55 gallon barrel. It would definitely take less material to enclose, and would be easier to mount for a drain back system.

truckncycle 08-10-09 02:14 PM

Does your garage have any windows? You could try reflecting the sunlight on to the floor and using it as a thermal mass. Although it does get cold enough here (high 20s) to wear a jacket in the garage, the bigger problem that I have is cooling. I would love an air conditioned garage. Our water heater and our car engines both provide some waste heat for the garage.

I was thinking about your radiator idea. One thought that I had is you could put the radiator inside with a fan and then treat it more as a forced air system. In the summer, you could add another radiator outside and cover it with cloth. Add a constant drip to the cloth an basically make a swamp cooler. WI may not be dry enough though.

I am assuming that your garage is already well insulated.

Daox 08-11-09 10:40 AM

The garage has two windows on the west facing side. They're not real big. Just your typical garage windows.

A radiator of some sort would be a nice thing to get more heat out of the barrel and into the garage. I'm sure I could figure something out that would do the same thing.

The swamp cooler thing unfortunately wouldn't work all that great up here. As you mentioned, its just too humid here.

The garage is not insulated as of yet, but that is something I am looking into as well. Obviously this would be the first step. With it insulated, I probably won't need a ton of additional heat. It doesn't have to be tropical, just some what comfortable to work in.

Daox 08-12-09 08:06 AM

Bumping for more suggestions. I want to hear some crazy ideas. :)

truckncycle 08-12-09 02:52 PM

You said you wanted crazy.

Move your compost bin into the garage and let the heat warm your garage.

One of the earth ships that I saw in a magazine as a kid had water drums in the wall. During the day, the outer wall was tilted down. The outer wall had foil on the inside of the insulation. The sun reflected off of the tilted wall and heated the water drums. At night the wall was closed and the thermal mass of the water kept the house warm.

Daox 08-12-09 03:35 PM

Not bad. I kinda like that! Foil mounted to a board would be a cheap and easy way of increasing collector surface area...

GaryGary 08-16-09 12:35 PM

Hi,
If you main garage door faces south, you could use this scheme:
Solar Workshop or Studio

It really works well -- provides both great heat and light. Its my all time favorite solar project.
You can work the thermal mass some by placing some water filled barrels in the opening where they will get some sun exposure. I logged some temperatures with a couple barrels, and could see difference -- I think the plot is in the article. It might take more like 4 to 6 to get the kind of temperature swing you want.

Where is the southern exposure that you have to work with relative to the garage you want to heat?

Gary

Daox 08-16-09 03:53 PM

I love that simple setup too Gary. Unfortunately, the garage door is not facing south. The main garage door faces east (towards the bottom of the picture).

The other thing I have to contend with is afternoon sunlight. The house will block a lot of sun come afternoon. I haven't done any analysis to see at what time the sun stops hitting the southern wall of the garage.

http://ecorenovator.org/pictures/house_aerial_1.jpg

On the up side, I just got back from the local electric vehicle build day. One of the guys there is a recycler and just got a truck load of thermal pane windows that someone was scrapping. I got 16 windows total, so I have some nice glass for projects (or window replacement, I only have single panes upstairs).

Daox 08-17-09 02:10 PM

Gary, have you come across any ways of using the hot air panels (inexpensive) combined with a method of increasing thermal mass? Something like using solar powered DC fans to duct air to blow over water barrels comes to my mind. What do you guys think?

GaryGary 08-18-09 08:26 PM

Hi,
I have a thermosyhon air heating collector on my barn/shop. I like it a lot -- no fans or controls. The air exits vents near the top of the collector on the wall up close to the ceiling. This area runs quite hot when the collector is running -- the vent exit temperature runs up toward 120F with good flow. I have thought about placing some thermal mass in this area. Just as a test, I've put a gallon can up there filled with water, and it heats up well over the collection period. The challenge would be getting enough mass in place to be effective.
Perhaps a plastic lined trough filled with water and hung from the ceiling? (you did ask for all sorts of ideas :)
Or, maybe even pick up heat from this area with a car radiator as Nathan does in this scheme:
http://www.builditsolar.com/Projects...rageNathan.pdf
The radiator could transfer the heat to a water tank -- if the tank was centrally located in the garage, and not insulated, it could act like a big radiator?

This is the thermosyphon heater:
$350 Solar Heating Thermosyphon Collector
Its only about $3 per sqat -- less if you could use your free glazing.

I guess another approach would be to 1) insulate well, 2) add something like the large area thermosyphon collector (lots of collection area), 3) add distributed thermal mass throughout the garage -- water barrels, or anything with lots of mass, and 5) keep the air well mixed (maybe a slow, efficient ceiling fan or two). This would allow the excess of heat collected during the day to be absorbed by thermal mass (which should help prevent overheating), and the good insulation should allow the mass to carry over the heat to the next morning.

I'm sure you already know about the Solar Site Survey -- avoids those "how can I be such an idiot" moments that we all have :)
Solar Site Survey

Gary

tzarkyl 01-21-10 01:33 PM

Garage heater
 
Hello all
This is my first post


one idea i had for heating my own garage was to simply have abs pipe on the roof and circulate antifreeze through that and have it cycle into the garage and for thermal mass i was thinking of removing the rubble from my "illegal but all ready present garage pit" snaking piping throughout and filling it with sand. i dont know if this is practical or not but i look forward to any input

Mike

GaryGary 01-21-10 02:08 PM

Hi Mike,
I think that in your climate, you would need glazing over the tubes to get worthwhile heat out of it in the winter.

Collectors normally have fins on the pipes so that the sun that falls between the pipes gets transferred over to the pipes by the fins -- otherwise, you don't get much benefit from the sun that falls between the pipes.

Once you glaze the collector, the ABS is not likely to stand up to the temperatures inside the collector. It might be OK when fluid is being circulated, but if the fluid circulation stops for any reason and the collector stagnates, the temperatures inside the collector will go very high -- to high for ABS.

Half inch copper tubing is probably the best choice. Here is one way to do the tubes, fins, and manifold:
Experimental Solar Collector Using Hybrid Copper/Aluminum Construction

I think the storage in the pit would be OK if you insulate the walls and floor of the pit. That is, you want the stored heat to go into the shop and not be lost down into the earth.

Not trying to discourage you -- its a very workable idea with the right materials and construction.

Gary

Christ 01-22-10 11:02 PM

Quote:

Originally Posted by GaryGary (Post 5539)
Hi Mike,
I think that in your climate, you would need glazing over the tubes to get worthwhile heat out of it in the winter.

Collectors normally have fins on the pipes so that the sun that falls between the pipes gets transferred over to the pipes by the fins -- otherwise, you don't get much benefit from the sun that falls between the pipes.

Once you glaze the collector, the ABS is not likely to stand up to the temperatures inside the collector. It might be OK when fluid is being circulated, but if the fluid circulation stops for any reason and the collector stagnates, the temperatures inside the collector will go very high -- to high for ABS.

Half inch copper tubing is probably the best choice. Here is one way to do the tubes, fins, and manifold:
Experimental Solar Collector Using Hybrid Copper/Aluminum Construction

I think the storage in the pit would be OK if you insulate the walls and floor of the pit. That is, you want the stored heat to go into the shop and not be lost down into the earth.

Not trying to discourage you -- its a very workable idea with the right materials and construction.

Gary

Simple marine plywood painted black? (As opposed to ABS).

I was trying to think of a way to use some tempered glass I have acquired... I'm considering making a few small thermo siphon air-exchange heaters to show my Father how they work... Build a box over top of a box with a duct inside, then put the glass over the top box, and lay it at an angle. As the air in the top box heats up, it draws in cooler air through the bottom box, and creates a small solar oven effect.

Wonderboy 01-31-10 09:57 PM

I haven't even been lurking here, and I nearly forgot this forum existed (I'm a semi-frequent poster on ecomodder)

I've been thinking about making a thermosiphon collector (they are also called Barra systems or Trombe walls) for the back of my house, which pretty much faces due south. I've looked at a number of designs for these (including the one posted by Gary - $350 solar heating thermsiphon collector) including this one on instructables. The corrugated clear plastic glazing, flap valves, and the ~10cm deep seems to be common design aspect. What changes between them are the thermal mass. I personally don't like the idea of using copper purely based on cost unless you can somehow find it for free, but I've considered both the metal screen painted with black BBQ paint, and/or aluminum cans with the bottoms cut out and painted with black BBQ paint. This seems to be like a pretty solid cost/thermal conductivity ratio to me.... that plus some concrete board attached to the surface of the building behind whatever thermal conductor is used to add some thermal mass.

Intuitively, I would think that in a climate like mine (Binghamton NY) where we receive 50 something sunny days a year, the most important aspect of a system like this would be its thermal "agility" and not its thermal mass. In other words, it would be more important for this system to pump as much warm hot air as quickly as possible when it IS sunny out during the cold months. I am not expert though, and when I try this out I will give feedback, just as I'd expect from anyone here who experiments with something like this.

Cheers :thumbup:


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