Heat your shop. Cool your shop.
For most of us, wintertime means woodworking. With the summer chores done, it's time to make sawdust. But if you live in a cold climate, toughing out a frigid shop can have a chilling effect on your hobby. Time to look into a shop heating system. But first, consider these four I's:
Bare building materials, such as wood studs, sheathing, and siding, readily conduct heat and cold. To tame that transmission, add weather stripping to doors and windows, spot-fill holes and cracks with canned expanding-foam insulation, fortify the insulation of heat-loss-prone garage doors, and insulate walls and ceilings to a value of at least R-13. If you work out of a basement, add cut-to-fit rigid foam insulation to the rim joists, adhering it in place with expanding-foam insulation.
To choose an appropriate-size system for your climate, confer with a licensed HVAC installer. He will ask such questions as: How many walls does your shop share with a heated structure? What are the dimensions, and how high is the ceiling? Do you want to maintain a minimum temperature when you are not in the shop?
Speak to your local housing code inspector to narrow the field of appliance choices. Eliminate systems restricted by your municipality and get the inspector's guidance on the legal installation of a system.
Some heat sources that pass the inspector's muster may still be frowned upon by your insurance company. Choosing a system not covered by your insurance -- such as a wood-burning stove -- could leave you with denied claims after a fire, whether your heater was involved or not. So keep your insurance agent in the loop.
Specifically targeting home workshops, manufacturers have recently introduced more and more forced-air furnaces onto the market—both gas and electric—making it easier to find an affordable model for nearly any shop size. Fan-circulated, heated air raises a room's temperature quickly, making a forced-air unit an economical choice if you heat only intermittently.
In an electric forced-air furnace, all of the power sent through the element is converted to heat, making the appliance nearly 100 percent efficient. Electric furnaces sit on the low end of the price scale. Installation is inexpensive and simple—often little more than plugging or hard-wiring into your existing electrical service. However, in most of the country, electricity is the highest-cost utility, so an electric forced-air furnace may make the most sense for moderate climates calling for only occasional or supplemental heat. If your electric panel can handle it, opt for a more powerful 220-volt model.
A gas-fired, ceiling-mounted forced-air furnace requires venting and a gas line. And through-the-wall, direct-vent versions require some modifications to your shop wall, adding to installation costs. But natural gas remains one of the most inexpensive fuel sources, so it makes good long-term sense. For safety in a fume- and dust-filled shop, choose a furnace with a separated combustion chamber that draws outside air for combustion.
Their propane-fired cousins work the same, but propane prices approach electricity costs in some regions. If your only fuel options are electric or propane, enter your utility prices into a cost calculator like the one available from the U.S. Energy Information Administration (http://www.eia.gov/neic/experts/heatcalc.xls) to guide you to the lowest-cost option.
These work by directly heating the objects (and people) in the room via infrared rays—much as the sun warms you when you step out of the shade. The objects, in turn, pass that heat to the air. Because it warms a room's heat sinks, such as its concrete slab floor and cast-iron tool tops, a radiant heating system requires less energy to maintain a steady temperature and feels comfortable at a lower thermostat setting, making it more cost-effective than its forced-air counterparts. And radiant heating won't dry the air or stir up dust like forced-air systems.
You can find radiant heaters powered by either gas or electricity in several forms: electric panels (right) in a variety of shapes that nestle into coves, baseboards, or even ceiling-tile grids; gas-fired, vented tubes in a variety of configurations to hang from your ceiling; and in-slab systems consisting of loops of hot-water lines (below).
Radiant systems cost more to install than forced-air systems and often have to be special-ordered and installed by expert technicians. And they take a long time to heat things up—a consideration if you're in your shop for just a few hours at a time. However, if you require consistent, all-day heat, strongly consider a radiant system.
Not-so-hot heating options
What about wood? Makes sense, right? You can burn your offcuts and mistakes for cozy heat. But wood heat has enough drawbacks to discourage it:
- Passing inspection may be difficult or even impossible in your community.
- Your insurance agent may balk at (or charge a fortune for) an open-flame appliance.
- Kiln-dried scraps burn hot and fast, so you'll soon be forced to switch to labor-intensive firewood. Even then, it will be difficult to maintain consistent heat.
Also be wary of vent-free propane- or kerosene-fired appliances. These low-cost heaters, sold as portable units or radiant panels, require plenty of fresh-air ventilation to prevent carbon-monoxide poisoning, causing you to waste energy warming cold outside air. And propane versions introduce moisture into the air -- a bad mixture with wood and cast-iron tools. Although some models come with low-oxygen shut-off sensors for safer operation, the trade-off can be inconsistent heat as you wait for the fresh-air supply to replenish.
All air conditioners work basically in the same way: A cycle of evaporating and condensing refrigerant cools the air on the inside of the room and releases heat to the outside. As an added benefit, cooler air holds less moisture, so an air conditioner removes humidity naturally: great for your comfort and your cast iron.
The main differences in air conditioners are Btu capacity and shape. If you can't stand the heat in your shop, here are AC units to consider.
Pint-size, rollaway, portable air conditioning units like the one shown below are low-dough options. But don't expect one to counter triple-digit heat, or cool large or uninsulated spaces. It's more useful in mild climates requiring only occasional cooling. And it needs only a 110-volt outlet and a door, window, or cut-out to accommodate its vent hose, which exhausts the hot air and humidity to the outside.
Window and through-the-wall units
Today's window units aren't the rattle-and-roar contraptions you remember from decades ago. Quiet-running and efficient, modern window units often feature remote controls and can even heat on chilly days.
You'll recognize through-the-wall units (sometimes referred to as "packaged terminal air conditioners" or PTAC) from hotels. More readily available to consumers nowadays, these units sell in a variety of room-cooling capacities.
A favorite in Asia and Europe, mini-split systems have a long track record, but have only recently gained traction in North America. These cooling units work just like home central-air units: an outdoor compressor coupled with an indoor cooling coil, but in miniature. The lightweight, outdoor compressor takes up little room, the interior cooling unit can be hung anywhere (no ducting necessary), and the connecting refrigerant and electrical lines require only a 3" hole through the wall.
For an added cost, many mini-split units offer a heat pump upgrade, adding the capability of drawing heat from the outdoor air and depositing it inside. While capable of heating the air much more efficiently than a simple electric heating element (some use one-third the electricity of their element-equipped cousins), they can't overcome outdoor air temperatures lower than about 35° . To compensate for the coldest part of the season, many units add less-efficient supplemental resistance-style electrical heating elements.
Download a chart summarizing several heating and cooling options here.