When the Nelsons of Belmond, Iowa, built their shop in 2008, a top consideration was how they would keep it warm in colder months. Brothers David, Dennis, and Neal turned to Chris McMurray for guidance on how to heat their 80×80-foot building.
“We laid out the heating, and I broke it down as to what their best options were for a shop that large,” says McMurray, who owns McEzs, a plumbing, heating, and refrigeration business in Meservey, Iowa.
McMurray says there are basically three types of systems to choose from.
1. Radiant Hydronic. This system uses water to carry heat from a boiler unit through a series of pipes placed under a floor or embedded in a concrete floor. “One of the biggest advantages of this system is that the entire floor is warm,” says McMurray. Boilers can be placed just about anywhere. That's because the flame is enclosed and the system is only heated to around 130°F.
2. Radiant Tube (Infrared). “Radiant tube heat, or infrared heat, is a heater that hangs from the ceiling with the reflectors,” says McMurray. “It's the one that, as you walk into a building, you get blasted with heat. It heats the object from the top down.”
3. Forced Air. This system doesn't heat objects but rather the air, and basically it uses a flame to heat the air. Most of the time this system hangs from the ceiling away from objects that can overheat. Because heat rises and heat is produced at the top of the room, this system is relatively inefficient.
Of the three, McMurray recommended in-floor heat for the Nelsons' shop. “My initial thought was that they needed to do this radiantly in the mass,” he says. “By going with radiant heat through the concrete, you can heat an area the size of the Nelsons' shop very cost effectively.”
The brothers also did their homework. “We talked with people who installed in-floor heat, and they said they really liked it,” says David Nelson.
“Right now I'm putting 95°F. water into that floor, and it's maintaining +60°F. in their shop,” says McMurray.
What's the feature the brothers like most? “The best part is that the floor is warm so our feet are always warm,” says David Nelson. “We can open the large door on a cold day to bring in a piece of equipment, shut it, and within five to 10 minutes, the shop is back to 60°F.”
How to decide
Ultimately, the size and type of heating system you choose will depend on the size of the shop, how often the shop is used, and how often large doors will be opened and closed.
According to Kenneth Hellevang, North Dakota State University, the heating system for a shop should provide about 50 Btu per square foot per hour depending on desired shop temperature and building insulation level.
“A 40×50-foot shop would require about a 100,000 Btu-per-hour heating system,” Hellevang says. “If a floor heating and forced air system is used, the heating requirement may be divided between the two.”