FROM UNIVERSITY OF MISSOURI EXTENSION
SOUTHWEST REGIONAL NEWS SERVICE
Contact: Bob Schultheis, natural resource engineering specialist
Headquartered in Webster County
Tel: (417) 859-2044
E-mail: schultheisr@missouri.edu

Specialist Offers Suggestions for Heating a Farm Shop

The shop serves multiple roles on the modern farm. It is a place for equipment, parts and tool storage, equipment maintenance, fabrication and service and an office.

The size of the shop varies too, depending on the farm size and the type of equipment to be serviced. Shop sizes can range from 30 feet x 30 feet for a small livestock farm to 40 feet x 60 feet or more for a 1000-acre crop farm.

“Most farmers I know wish their shop was bigger than it is,” said Bob Schultheis, natural resource engineering specialist with University of Missouri Extension. “Heating those bigger and bigger shops can be a major expense.”

Knowing how a shop will be used is an important factor in selecting a shop heater. Schultheis gives a rundown of the options available to maintain a preferred shop temperature of 45 to 60 degrees Fahrenheit when occupied and 40 to 45 degrees when not in use.

Radiant (infrared) heaters provide the most instant heat, are easily changed, and relatively safe. Portable floor-type radiant heaters can provide localized comfort without heating the whole shop, but are more expensive and less dependable than ceiling-mounted units.

Radiant heat makes a room at 60 degrees feel almost as comfortable as one at 70 degrees with forced air heat.

“As you raise the height of the heater, the pattern it heats increases too,” said Schultheis.

He suggests sizing radiant heaters at 40 BTUs (British Thermal Units) per hour, per square foot of floor area.

“Gas-fired or waste-oil forced-air furnaces are a good choice for heating large areas,” said Schultheis.

Ceiling-mounted units help keep hot air from stagnating near the ceiling. Waste oil units are especially economical to operate, provide a quick heat source, and most will burn No. 1 or No. 2 fuel oil as well as waste oil.

Schultheis says to size the furnace at 50 BTUs per hour per square foot of floor area. Use a minimum of 70,000 BTUs per hour if the shop is fan-vented at 1,000 CFM to remove welding fumes, engine exhaust or dust.

In-floor heaters are the most expensive to install, and consist of electric resistance cable or hot water pipes buried in concrete over rigid foam insulation. These make the floor warm to work on, are quiet, and reduce dust circulation. However, it takes the system several hours to warm the shop to a comfortable temperature. 

“These work best in conjunction with a ceiling-mounted forced-air furnace near and to the side of the big entry door, directing the heat to the back of the shop and providing quick heat recovery when the door is opened,” said Schultheis.

Size electric heat cables at 15 watts per square foot or water pipes at 50 BTUs per square foot in the bench area and 4 feet out into the service area. Keep maximum floor temperature at or below 80 degrees to prevent foot discomfort over time.

Unvented fuel-fired space heaters offer relatively inexpensive supplemental heat, but must have outside ventilation of 4 cfm per 1000 BTUs per hour of heater capacity to prevent buildup of poisonous carbon monoxide.

Electric resistance heaters are efficient, but consider several smaller units instead of one large unit, due to their high operating expense.

Regardless of the heater type, Schultheis advises, “Insulate the shop like you would your house. The better insulated the building, the better it retains the heat your system produces.”

For more information on planning farm shops and their heating systems, get a copy of MWPS-26 Farm Shop Plans Book, from Extension Publications at 1-800-292-0969 or order on-line at http://www.extension.missouri.edu/explore/mwps/MW0026.htm. Schultheis can be reached at the Webster County Extension Center in Marshfield at 417-859-2044.

University of Missouri Extension does not discriminate on the basis of race, color, national origin, sex, sexual orientation, religion, age, disability or status as a Vietnam era veteran in employment or programs.

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