Canadian Woodworking

Heating your shop

Author: Michael Kampen
Published: December January 2005

There are a few things to consider when heating a shop. To select the best heater you have to take into account such things as the size of the shop, ceiling height, and the amount of insulation.

If your shop is in a garage or separate structure then there are several options to choose from. There are two main types of heating: space (convection), and radiant. The first type heats the space by heating the air, and the second heats objects in the space without heating the air first.

An infrared radiant heater is a practical choice when you wish to heat a poorly insulated space. By heating objects in the room directly, you do not have to be as concerned with losing heated air. I have installed industrial versions of these in wash bays of car dealerships and was surprised at how effective they were in the damp, wet, cold of a west coast winter, even though the bays were open to the elements. Lee Valley sells a radiant unit that would take the chill out of a poorly sealed shop. If your shop is larger you may require two of these.

Electric space heaters warm the whole room by heating the air in it. The least desirable of this type is the baseboard heater. They rely on the natural tendency of hot air to rise in order to heat the room. With equipment and material stored in a shop, space heaters tend to get buried behind things and filled with dust. This reduces their efficiency drastically, as well as making them a potential fire hazard.

A more appropriate choice for a shop would be a fan-forced heater. These use a fan to pass air over a heated element. They are far more efficient and less likely to suffer from excessive accumulation of combustible dust. They will heat a room much faster than an equivalent wattage baseboard heater. There are several versions of this type of heater.

My shop is in a separate building and is divided into two separate rooms. One side is a studio, which more closely resembles a room in my house. I chose a pair of inwall fan forced heaters rated at 1,500 watts each. These mount between studs that are on 16″ centres and can be controlled with wall-mounted or built-in thermostats. These heat the 350 square foot space quickly and efficiently, and would not look out of place in any room in the house.

By far, the most popular way to heat a shop is the 4,800-watt construction heater. These are also the most cost effective way to heat a shop, and can be found at building supply stores for approximately seventy-five dollars. These have to be supplied by an electrical circuit wired with #10 wire, a two-pole 30-amp breaker, and the appropriate receptacle. I find the built-in thermostats on these units to be inaccurate and flimsy, and would recommend that a wall thermostat switch the receptacle supplying the heater. When used with a wall thermostat, the built-in one on the heater must be set to its highest setting and left there, or it must be bypassed.

To get an idea what it would cost to heat your space, look at your last electricity bill and divide the total dollar amount by the total KWh. This will give you the true cost per kilowatt-hour with all of the surcharges, et cetera, included. Take this number and multiply it by the KW rating of your heater, in the case of a construction heater, 4.8KW. This will tell you how much it will cost to run that heater for one hour. With current electricity prices here in British Columbia, it costs about 25 cents an hour.

One safety precaution to keep in mind no matter what type of heating you choose is to blow the dust out of the heaters on a regular basis. What is a reasonable schedule depends on where you have the heater and how dusty your shop is. For construction heaters, the best method is to unplug it and take it outdoors and carefully blow it out with some compressed air.

In my next article in this series, I will look at some typical electrical loads and their requirements in your shop.

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