Using a propane heater and strip curtains to allow sunlight into a garage while keeping the cold out and the heat in.
The garage I rent to work on the DeLorean is pretty good, and now that it has electricity it'll be easier to work in there as it starts to get darker earlier in the winter. But a major issue is figuring out how to heat it. This is a single-walled building that is over a hundred years old, with visible gaps between some of the boards, and even plants growing into the garage from the outside.
While this is a two car garage, I only really have one full stall and about 3/4 of the second stall, as the landlord needed to the front of the second stall to hold garbage cans for the adjacent apartment building. He did a good building a sealed walled-off area between the two parts of the garage; there is effectively no smell from the garbage cans, and I still have plenty of space to work.
While I could use an electric heater, they don't really put out enough heat to warm the entire garage. There's also the issue of having a single 20 amp circuit; if I use any power tools, I might blow the breaker. Since the breaker box is behind a locked door that I don't have access to, this might shut me down for the day.
No matter what I do, the garage isn't exactly going to trap in the heat -- there is zero insulation, and in fact you can see light streaming in through some gaps between the boards in some places.
I decided to go with a propane heater. This requires no electricity, and uses the same kind of propane canisters as outdoor propane grills. The unit I choose puts out 18,000 BTUs of heat, which is roughly four times that of an average baseboard electric heater. It is also portable, so I can move it around the garage. That said, I need to be sure to keep it far away from the car when working with gasoline.
I don't have to worry much about fumes collecting while running the heater -- the garage is not air-tight by a long shot, and should seep through the structure without much trouble.
This unit puts out quite a lot of heat, but the safety features can be a bit annoying. A strong breeze can blow out the pilot light, so I wound up covering the back of it with a jacket to keep from having to relight it on windier days. Only the very front gets hot -- the rest of the heater is cool to the touch -- so there isn't any danger in doing this. I also have to be careful not to bump into it, as this triggers the quite sensitive tip-over shutoff feature.
Containing the Heat
An open garage door provides a lot of light, which is very desirable. However, it also lets out all of the hot air from the heater.
The solution is to cover the door with some kind of transparent barrier. I remembered seeing plastic strips hanging down from an industrial freezer once, and thought that might be a good solution. strip-curtains.com sells exactly that sort of thing. I purchased a 108" x 84" low-temperature strip curtain kit with the bullet-style face mounting and 50% overlap for about $235 shipped.
I wanted the curtain mounted inside the garage so that I wouldn't have to take it down every time I left. To handle this, I ran a 2x4 across the garage, -- just under the opened door and just beyond the door rails -- and attached it to the walls to act as a header. I cut a second 2x4 in half, mounted them on gate hinges and attached them to the walls just over the header. This created a kind of double door that I could hang the curtains from them. I mounted some simple brackets made from scrap 2x4s on the walls to keep the weight off the gate hinges when the "doors" are open.
When in use, the tops of the "doors" rest on top of the header when closed; a piece of scrap 2x4 acts as a block to keep the doors from swinging in our out as you move through them. These curtains also creates a kind of green house effect, trapping in heat from the sun while containing that from the heater. When I need to move the car in or out or it's nice enough that I'm not worried about trapping heat in, I can open the "doors" inward and lock them flush against the walls on crude brackets made from scrap 2x4s. I just need to make sure the "doors" are supported at all times, as the weight and length of the 2x4 and the curtains cannot be supported by the hinges alone.
I wanted the curtains to go as high as possible and thus be as close to the top of the door as possible. I made sure to first roughly mount the header, and then tried to close the door to make sure there was enough clearance. This was important as the distance between the garage door and the header change as the panels of the door rotate along the rail. In the final setup, the garage door just clears the header when the curtain "doors" are open, but will hit the curtain "door" if they are closed, or when attempting to close the garage door while the curtain is in place. I don't have a problem with this, since it's easy enough to open the doors before leaving for the day.
Storing the Propane Canister
One of the issues with using propane is that you can't store the canister indoors. The problem is that it can slowly leak, which in turn can fill an enclosed space with highly flammable gas that can easily combust when an ignition source is introduced (such as flipping a light switch, or plugging in a fan, or possibly even as the metal wheels of the garage door slip against their rails as it is opened). Since propane is heavier than air, you may not smell the gas until its too late. While I'm not worried about fumes while the using the heater, a buildup of gas while I'm gone could be catastrophic.
Because of this, I'm currently driving the propane canister home and storing it under my grill when I'm not at the garage.
I may build an airtight box inside the garage that would fit the canister, with a hose positioned near the bottom to safely funnel any leaks out of the garage. I'd also have to put a screen over the end to keep any animals out. It might be worth a try, and would certainly be less trouble then dragging the canister home and back all winter.
Results and Future Updates
We'll see how well this works this winter. We had a particularly windy day with 30 degree temperatures, and while the curtains fluttered around they did keep the wind from blowing through the garage, and kept the heat in. It wasn't like having full-on indoor heating, but it worked well enough that I didn't have a problem working with the metal tools and engine; without heating, metal feels extremely cold and is hard to hold onto for any length of time.
I'm considering getting a second set of strip curtains so that I can have 100% overlap, as at 50% overlap there's still a fair bit of breeze that gets through on windier days. Even so, it does keep more heat in and wind out than if I didn't have them.
A recent snow storm showed that I should probably get some expanding foam to fill in a few gaps around the walls -- snow was blown through the cracks into the garage. I did some of this when I moved in, but apparently I missed a few spots.