It’s now the time of year when contractors seek the aid of air heaters for temporary jobsite heat. In the past, many contractors employed open-flame, direct-fired heaters. This technology delivered intense heat at the outlet and converted 100% of the fuel, so contractors thought they were getting efficient heating.

However, there are significant drawbacks to this technology, and moisture is a critical one. “Every 100,000 BTUs of fuel burned with a direct-fired heater results in one gallon of water as a byproduct,” explains Ken Cannella, product manager for Wacker Neuson Climate Control products. This moisture can result in mold and bacteria growth when used inside an enclosed building and the water vapor can freeze and cause work delays.

Safety has also grown to be a concern. Positioning the outlet of an open flame heater too close to a flammable object can result in a fire. “It’s becoming more common that insurance companies will not underwrite the use of open-flame heaters for many types of construction projects,” says Ed Jaroszewicz, director of Climate Control products for Wacker Neuson Corporation.

Direct-fired heaters emit noxious gasses like carbon monoxide and dioxide that not only present health risks but also cause problems with concrete. “Carbon dioxide gas will collect on the top layer of concrete, which can cause chalking,” adds Cannella. “Plus intense heat from direct-fired heaters results in unwanted curling and premature cracking problems.”

Indirect Advantages
This is why there is a changing tide of popularity to the Arctic Bear™ Series heating systems from Wacker Neuson. “Over the last few seasons, inquiries for and sales of indirect-fired units have risen significantly,” mentions Jaroszewicz.

Moisture control lies at the heart of this amplified interest. The construction process adds plenty of moisture to the structure. Whereas direct-fired heaters introduce additional moisture which only exacerbates the situation, the dry heat produced by Arctic Bear™ indirect-fired heaters enables construction projects to dry out much faster, keeping construction activities moving forward and ensuring projects are completed efficiently.

The flame on an indirect-fired heater is safely contained inside a combustion chamber, offering clean and dry heat at the jobsite. A flue for venting emissions away from the work area is provided with indirect-fired units, so the carbon monoxide and dioxide, nitrogen oxide and moisture problems associated with direct-fired units is not a concern. “This is why our indirect-fired units can be safely positioned inside or outside an enclosed structure,” adds Jaroszewicz.

The high intensity heat of an open-flame heater results in air stratification, creating uneven heat throughout the structure. While these units convert 100 percent of fuel to heat, the inefficiency of the direct-fired system requires more BTUs, more fuel and a longer period of time to heat the structure.

Whether placed inside or outside, indirect-fired heaters use ducting to route warm, dry air throughout the entire structure. Many Arctic Bear™ air heaters pressurize the inside space for more efficient and faster heat up than direct-fired units. Exclusive Recircul-Air™ technology recirculates the air from inside the space for faster, more efficient heating of the entire space.

“By drawing and reheating warm inside air rather than cold outside air, indirect-fired heaters achieve much higher efficiencies and savings,” says Cannella. “We have helped contractors realize upwards to 50% fuel savings.”

Recircul-Air™ also allows contractors to use less BTUs to heat the structure. “With direct-fired units, a contractor may need a larger heater because it does not pressurize the structure or recirculate the air,” adds Cannella. “However, that same structure may require 50% less fuel by using an Arctic Bear™ heater with our exclusive Recircul-Air™ technology.”

To size the right heater for the job, Wacker Neuson heat estimator programs take the guesswork out of heater selection. “Our fuel cost estimator takes into account a number of factors like building ‘tightness,’ size, required temperature rise and fuel used to determine the right size heater and the projected fuel costs for operating it throughout the season,” says Jaroszewicz. “Contractors also find other advantages, such as redefining their workflow processes that ultimately reduce heat protection costs.”