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I read on some online forums where there are those who restrict their woodworking to one season or another because of the weather. I’d go nuts. Most of my life I’ve lived where winter and almost winter were the only seasons so I’ve learned a few things about heating a woodshop.
I should be forthright about where all this is going. If you are looking for the answer to all your worries you won’t find it here. I suppose the answer is to install a proper heating system that’s designed to keep your shop at the temperature you prefer to work, and that includes not only a suitable unit to produce the heat, but also the necessary insulation and other adjustments to keep it in once you’ve made it.
In my fourth shop (I’m on my sixth) I had almost the ideal setup. My shop was heavily insulated and the walls were covered with drywall. In one corner I had a downdraught, natural gas furnace that kept the shop the same temperature as my house even during extended periods where it was -13° F (-25° C) outside, or colder. I had no duct work, except the deflector under the furnace, but it was a full size furnace all the same. Installing that kind of unit isn’t cheap. While forced air will heat a shop admirably, you have to clean in the inside and change the filter weekly at least. That’s not the main reason I prefaced the word ideal with almost.
That shop had two overhead garage doors. Well, it was a garage wasn’t it. The main door, a sixteen footer, stretched across the front of the garage while a second eight foot door was located on the back wall. Both of these abominations were flimsy and cheap, just pretending to be doors. The panels in them were cardboard and less than a quarter inch thick. While it can’t hurt anything now, I still hesitate to mention that if anyone had wanted to break into my shop they could have popped out several panels and gained easy access, especially from the back where there would be no-one to see them. I lost many BTU’s of energy through those things until I backed them with insulation and covered them in plastic to stop the draughts. I couldn’t use the doors any longer but hey, it was a shop, wasn’t it? Yet a common furnace isn’t ideal either.
The best option, with no open flame to create a fire hazard, would probably be in-floor, hot water heating. This summer I’m building my eighth shop – guess what it’s going to have. I’ve waited a long time for a dedicated shop space that didn’t displace my vehicles so I reckon it’s about time. However, many people don’t have the wherewithal to spend what it takes to install a system that doesn’t require settling for second best. Although there are many things you can do to help better your situation, I’m afraid there is no best answer to the question, "what’s the best way to heat my shop?"
On the brighter side, not everyone lives in North Central Alberta, Canada. In New Jersey, for example, I really don’t need to do that much to the shop to continue using it for much of the winter. There will be a few weeks where I may not want to set foot out there, and that may be acceptable to most. It certainly is a cheaper alternative to installing a full blown heating system. So, to cut to the chase, let’s start talking about some of the less expensive alternatives to constructing a whole new shop space.
Blocking the Leaks
Before getting into the various options for generating heat in the shop, it’s a good idea to talk about modifications that will help control your temperature all year round. Heating a shop is a lot like filling a goldfish bowl. If you drilled several holes in the bowl, the water would continue to leak out until what’s in the bowl is the same as what’s outside of it. Unless you want a dry bowl you have to keep pouring in the water until your water bill goes through the roof. When you walk into your shop and close the door behind you, it may look like it is a sealed space but it isn’t. Unless you have been through this process already there will be holes all over – providing your heat with places to leak out until your shop is the same temperature as outside.
You are probably already aware that windows, the areas around wall outlets, the space between the door jamb and the wall frame, the spaces between the trusses at the edge of the roof, the sill plate, and many other places are prime candidates for heat loss. A hole isn’t required. Thin glass in a poorly constructed window can facilitate the loss of heat even if there aren’t any physical holes. These are certainly all places to look. But many work in shops with bare stud walls and, while that makes stopping up the holes easier, it also means they have more pressing concerns.
A fully insulated wall covered with a vapor barrier and either drywall or some other material, will provide you with the best protection from the elements. Not only will it keep your heat in but it will prevent excessive heat buildup during the summer months. If you do nothing else you should at least consider insulating the walls – and the ceiling.
At present I haven’t insulated my ceiling either. It has been my biggest heat loss area, taking every BTU I produce and sending it right out into the night sky. I can say from experience that if you don’t insulate the ceiling you might as well now. And don’t be afraid to add extra insulation. My fourth shop had a double layer of fiberglass in the ceiling that, after installation, made a real difference to my gas bill.
Garages typically have awful windows. Rather than go to the effort and expense to replace them, I have always had good luck with curtains. A thick curtain made out of wool or an old jacket works well. To further help out, the outside face of the curtain can be lined with one of those foil space blankets which will reflect outside heat back out, and reflect the heat you are creating back into the shop. You are limited only by your pocket book and imagination. As with other nooks and crannies, consider running a bead of caulk around the trim, or the edge of the window if you don’t have trim. Draughts really make the shop unpleasant.
Overhead doors are hard to live with unless you have a proper insulated door. There are several alternatives here. The most severe would be to remove the door and frame out the opening. Then it can be insulated and drywalled eliminating the problem entirely. The door could be replaced with a real door. You could frame out a removable wall that covers the door that could be moved if you ever decided you wanted the door to open (or could afford an insulated one). It is also possible to cover the door to seal out the elements. I covered one of mine with plastic to seal out draughts, then fitted white Styrofoam between the horizontal supports. The door was finished off by tucking pink fiberglass into every nook, binding it together with a coating of plastic. The effort was very much worthwhile but rendered the door inoperative. In my present shop, I opted to wedge thin, flexible sheets of foil covered insulation between the metal brackets that support the door. I can still use the door but it lets far more heat out, the tradeoff I’ve made so I can open the door. Out of these options you should be able to come up with an idea that works.
Generating Heat
Options abound in the world of heaters as well. With the variety of heating units available you should be able to put together some kind of system that will work for you. Here are my thoughts on some of the alternatives.
Electrical heaters are available in many forms. Stay away from the cheap shop heaters you see that have a heater coil and built in fan. They are usually rounded, gray boxes that cost around twenty dollars. If you want to throw a little extra heat on your feet while at the bench, they’re fine but they won’t generate enough heat to increase your shop temperature – even if it’s well insulated.
The small ceramic heaters generate many more BTUs and go a lot further to heating your shop. Unfortunately, I haven’t seen one that is effective at providing more than just a zone of warmer air in a shop of any size. If you are working out of a garden shed you may find these provide you with enough heat but in a garage they simply won’t do.
I have a radiant heater purchased out of the Lee Valley catalog and it is mounted to the ceiling behind my bench. This little heater has two settings and heats by increasing the energy level of other surfaces in front of it rather than blowing warm air. It works great to keep my back, and the general bench area, toasty warm while I’m working but it would never be able to heat up my 380 square feet of space. It would have to be used in conjunction with some other form of heat.
I have heard several comments about the radiator style, oil filled heaters that you can buy. Although I have no experience with them myself, many people seem to be happy with them Unfortunately, like my radiant heater, these heater don’t move air around resulting in a concentration of heat on one place. In my case, that is by design. Otherwise a small fan may be required to circulate the air through out the shop.
I personally don’t recommend heating with kerosene, although many would disagree. I had one of those kerosene fired radiant heaters and used it one January to complete a project in the shop. It did little more than keep me a little warmer than the rest of the shop and had the unpleasant side effect of contributing to a case of pneumonia that I developed while using it. They stink, produce voluminous noxious gases, and don’t heat well.
The kerosene fired or propane industrial tube heaters are very popular. As I usually work in a well enclosed space, I would never use them as they produce abundant BTUs, but also abundant carbon dioxide. If you work in an open space like a barn or machine shed, these heaters may work for you. In a garage, I don’t think they are a good idea.
Propane heaters are getting very popular. The biggest thing to watch for is whether they require venting and if you have a handy place to store the bottle of propane. I purchased a Mr. Heater Buddy along with a twelve foot extension so I can keep a twenty pound bottle of propane outside one of my shop windows. This little heater burns very clean and requires no ventilation. It is very safe as it has an automatic shutoff if tipped or the carbon dioxide level in the shop gets too high. Unfortunately, it will only heat about 200 square feet effectively so, by itself, it is no solution.
I also have one of those wall mounted ventless gas heaters you can pick up in the Home Depot and other places. Mine can be used with propane so it can also run off my bottle. These units require a great deal more gas to run and it won’t heat for very long off a twenty pound bottle. It will provide enough heat to heat my shop all on its own but in exchange, the burning gas creates so much water vapor that I have to constantly monitor my cast iron for rust. I feel that the humidity it creates isn’t worth the heat. If you are going to install one, go for a vented heater. It will require a more extensive installation but keeping the humidity out of the shop will be worth it. At the same time, it would be best to consider a dedicated natural gas line – running out for propane all the time is a real inconvenience.
For many shops, the ideal solution would be a ceiling mounted, gas fired heater with a circulation fan. I’ve dreamed of one of these for a few years now but I haven’t had the money to put one in. Having one requires that a dedicated gas line be run (which requires a building permit, a certified contractor and at least two inspections in my area) in addition to the expensive of the heater itself. These heaters are also available with electric elements if you prefer not to run the gas line. However, you would have to install a separate 220V line instead. Either way, the costs are higher and who knows which would be more expensive to run. In my area the electrical version would probably be slightly cheaper if only because of recent, staggering increases in the gas price. These heaters heat by brute force and will get the job done.
Of course all this leads to the gas fired forced air furnace, which is very nice to have. From experience I can say that if you do have one of these, you will always be warm and cozy, and your significant other may never see you during the winter. Although I had to clean it regularly because of the explosion hazard, I loved mine. The biggest drawback was it’s proximity to my bench. That made me hesitant to used highly volatile finishes while it was running. However, I had enough insulation that I was able to shut the furnace off and apply brushed on lacquer or oil based finishes without much heat loss.
The cream of the cream of course would be the in-floor, hot water system. They are the most expensive to install but you can make that back on the energy savings. The boiler unit is usually placed in it’s own room providing you with dust-free, spark-free heat in which you can apply finishes without worry. My new shop has one of these already in the plan.
My Shop – A Heating Example
After all that, it may be helpful to look at some of these things in the context of a package. Therefore, I will give you an idea what’s going on in my shop this winter.
First, here is some background data. The average temperature here between December and February is between 32° F and 37° F (that’s averaging the highs and lows – because some woodworkers have to work at night). November and March are in the low forties. However, the last couple of years, we have had periods of weeks where the average is at least 10° less than that. This January (2004) must be close to 25° F.
My shop is around 380 odd square feet. It is 2 by 4 stick framed with a high truss roof. I have one entry door (which is well insulated and weather-stripped) leading from the house, two large double pane windows and a sixteen foot cheap aluminum overhead door. The walls are all insulated to R-13 with Kraft paper faced fiberglass insulation. Of the three full walls (no having an overhead door in them) one is covered with T-111 tongue and groove paneling (which I highly recommend as you can attach anything to it), one is drywalled, and one still has the paper showing – unfortunately. The floor is four inches of concrete, slab on grade, and is now the biggest heat sink in the place. The ceiling is drywalled but I have no insulation up there.
Knowing all that I have done a few things to heat up the shop. Obviously, I added much of the insulation myself. The wall my shop shares with the house was insulated when I moved in. The other two walls and the framed area around the door I did myself. I also added the T-111 paneling – the drywall being there when I moved in. In addition to the insulation and paneling, I added thick wool curtains to the windows. Unfortunately they do not cover the whole window – which was partly beyond my control and partly by design. I couldn’t find enough of the thick, red wool to cover all of the windows so I decided to cover the bottom two thirds so light could filter in from the top. In retrospect, I should have found a large piece of fabric as I lose heat that way. I also outfitter the sixteen foot overhead door with foil faced, Styrofoam insulation (as I mentioned earlier). It doesn’t seem to affect the temperature level in the shop but it must do something. My bench is right beside it and I know I feel much warmer with the thin layer of insulation than without. Lastly, I installed the Lee Valley radiant heater to the ceiling facing my bench to keep me warm, and I use the Mr. Heater Buddy to generate the rest of my heat. So, how did I do?
The Buddy heater was the second last addition I made to the shop. After purchasing it I did a test to figure out if I was going to return the unit or not. I ended up keeping it. You can see from the set of results in this graphic file that over an extended period of time on an average temperature day, through out the sunny afternoon and in the dark of evening, that I was able to maintain a shop temperature about 28° F higher than the outside temperature. On an average temperature day then, I was able to keep it warm enough to work in my shop. I prefer not to glue when the shop falls below 60° to 65° F but you can see from the chart that the outside temperature wouldn’t have to be much higher to allow this.
The final change I made was the insulation in the garage door. From this graphic you can see that on the evening I tested it, it seemed to make little difference. The shop temperature was still around 27° F higher than outside, but I can say from experience since, that during the daytime, I think it helps keep a slightly higher temperature difference than that.
While these results aren’t quite scientific, they are as close to scientific as I could get, you should still be able to get an idea of the increase in shop temperature I was able to achieve with a couple inexpensive heaters and some insulation. In total I paid a fifth of what an insulated door would have cost me and I was able to achieve a satisfactory result. If I was planning on staying in this house longer, I probably would have hired a gas fitter and bought one of the natural gas, wall mounted, vented heaters you see in the big box stores. That way I would have all the heat I needed without the humidity of the ventless models. And I would have done that in place of buying the little heaters I have now. I would already have, or been in the planning stages of, removing the overhead door and replacing it with a wall ( and a double door) and I would also have insulated my ceiling. Those modifications would have seen me through years of woodworking.
Still, I am on the verge of moving and I will be building a new shop – super-insulated with in-floor, hot water heating. It will be so nice. However, what I have now allows me to work in the winter and be reasonably comfortable. That’s the point; woodworking keeps me sane. Be warm, work safe, and happy woodworking.
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