Whole-Shop Heating Systems
We woodworkers love the winter, when outdoor chores end and nasty weather drives us indoors to where we wanted to be in the first place—our workshops. But if our shops lack heat, we could be sidelined for much of the woodworking season.
To fix the problem, many people turn to portable space heaters for warmth. But these units often are marginally effective at best. For real comfort, consider a dedicated shop-heating system.
For about the price of a good cabinet saw, you can buy the components to heat a 24x24' workshop. You might even find a used appliance for a fraction of that cost by checking with local heating contractors. Professional installation will cost in the range of 20–30% more. Here are some smart, widely available options. (For a quick overview of the types, see the chart and sources at the end of the article.)
Shops share some of the same heating concerns as homes, but significant differences exist, as well. Keep the following in mind as you plan a heating system.
• Insulation: You can’t bring warmth effectively in until you keep the cold out by sealing and insulating your shop. The up-front expense is small compared to what you’ll save in the long run.
This difference is easy to see looking at heating requirements, figured in British Thermal Units (BTUs) per hour. For a 24x24' shop in the upper Midwest, where winter temperatures dip below 0°F , manufacturers quote an average of about 25,000 BTUs per hour for an insulated shop, and more than 50,000 for one without insulation.
• Air quality: Fill the air in your shop with enough fine sawdust or finishing fumes, and you’ll have the potential for an explosion. So stay away from open-flame heaters and from electric units with exposed heating elements. Choose a unit that, if electric, has shielded elements, or, if gas-powered, draws outside air for combustion rather than shop air.
• Insurance and permits: Before you install a heating system, check out local code requirements governing the types of heaters you can use, installation restrictions, and required permits. Talk to your insurance company, as well. Skirting these steps could lead to fines, or to denied claims if you have a fire—even one unrelated to the heating system, such as one caused by improperly discarded finishing rags. (You always lay your oily rags out to dry flat, right?)
• Unique requirements: Differences in climate, construction, and usage dictate different heating needs in every shop. Check out the sidebar “A heated debate” at the end of this article, for more considerations.
The old reliable: a gas-fired forced-air furnace
Forced-air heaters fall into a couple of categories: self-contained heaters that mount to the wall or hang from the ceiling and the traditional ducted furnace, found in many homes.
Self-contained heaters, such as the model shown in the photo above, have been standard issue in shops and garages for years. They don't eat floor space, and are relatively easy to install because they don’t require ducting. These heaters produce heat from economical liquid propane (LP) or natural gas. Most circulate warmed air using a fan. Unlike older versions, some modern units draw combustion air from the outside, as shown in the drawing below.
A traditional furnace distributes air through a series of ducts to just where you want it. Installation involves more challenges, but a furnace also accommodates central air-conditioning.
If you choose a furnace that doesn’t draw outside air for combustion, install it in a separate room to minimize dust and fume hazards. The drawing below shows one way to do this.
Turn on the tube
If you have access to gas, but don’t want forced-air heating, check out a ceiling-mounted radiant tube heater, shown in the photo and illustration, above.
Tube heaters burn LP or natural gas, which warms the air inside a long metal pipe. Heat radiates downward, warming objects it strikes. The system has no external fan to stir up dust in the shop.
Heat under feet
When building a new shop (oh yeah, it’s a “garage,” we won’t tell), you might consider hydronic, in-floor radiant heating. These systems are becoming more affordable and increasingly popular in homes, shops, and buildings of all types.
As shown in the photo below, the heart of a hydronic system is a network of plastic tubes, usually imbedded in a concrete floor. Hot water pumped through the tubing heats the concrete, which acts as a giant radiator and warms everything above it.
You can power a hydronic system for a two-car-garage-sized shop with a small water heater. (If it’s a gas unit, you still need to isolate the flame from shop air, of course.) You can build a “closed” system filled with antifreeze, or run a water supply to the shop and let the heating system provide hot water, as well.
Electricity has traditionally been an expensive heat source. Even so, the setup costs with other systems may make it worth considering, especially if your BTU needs are low or you spend limited time in the shop during cool seasons.
Unless you’re dedicated to very traditional woodworking, you already have electric service to your shop, so chances are you won’t need anything more to run an electric heater. Units that run on 220 volts generally produce more heat.
Electric heaters come in many sizes and styles, and it’s easy to add more based on need. Portables don’t require special insurance, and even permanent units seldom require a permit.
Radiant panels, such as the ones shown below, from Radiant Electric Heat, Inc., pass electricity over a large metal plate to produce warmth. These heaters are fairly immune to dust and fume dangers.
According to the manufacturer, heating with radiant electric panels costs about the same as using a natural gas or LP forced-air system. Electricity costs more per BTU but, because radiant heating warms objects and not just the air, electric panels heat using fewer BTUs.
Other electric options include in-floor, ceiling-mounted, and simple "plug-andplay" baseboard units.
Is wood good?
A wood-burning stove seems like the ultimate romantic source of shop heat for many woodworkers. After all, you’re making fuel all the time in the form of scraps and (heaven forbid) mistakes. But wood stoves do have drawbacks.
First, those kiln-dried scraps burn up pretty quickly, so you’ll need a supply of split firewood. Even with good wood, an inexpensive stove can be hard to regulate, causing wide temperature swings. And unless you make special trips to stoke the fire, you’ll lose your heat when not in the shop.
Insurance companies may balk at a stove’s open flame and hot surfaces. Also, some communities with strict air standards regulate the use of woodburning stoves and fireplaces. A stove may look great in the shop, but isn’t the safest heat source.
For additional help with setting up a heating system in your shop, contact a local heating contractor, or take a look at the products offered by these companies:
Radiant Electric Heat, Inc.
Radiant electric cove, wall-mounted, and baseboard heating systems. 800/774-4450
Ceiling-mounted, self-contained heating systems 800/695-1901
A heated debate
How many BTUs should you use?
1. Does your shop stand alone or is it attached to another heated structure?
2. How many exterior walls does your shop have, and are they currently insulated?
3. Is it a dedicated shop, or a space also used for a garage or other purposes?
4. What are the shop dimensions?
5. How high are the ceilings?
6. What construction materials make up your shop (wood, brick, concrete block, etc.)?
7. Do you know the insulation values in the walls and ceiling?
8. How many windows does the shop have, and are they single-pane or high-efficiency units?
9. How many exterior doors are there?
10. Does the shop have overhead garage doors? If so, are they insulated?
11. How many hours per week do you spend in the shop during cold seasons?
12. Will you heat your shop to at least above freezing when you're not in it?
13. Do you have a gas line near the building, or will you have to run one?