Indirect-Fired Heaters Offer Many Advantages at the Jobsite

The days are becoming shorter and a chill is in the air. The beginning of fall signals the time where contractors in Canada hurry to finish enclosing structures, so crews can move inside and continue working during the long, cold winter months.

 It is also the time where contractors begin to consider their heating needs, so the trades can continue to work and keep projects on schedule. “Many contractors wait until the weather gets cold to consider their jobsite heat needs, but those who wait may find that the right heater may not be available,” cautions Ken Cannella, product manager for Wacker Neuson Climate Technology products.

With the number of heating options and considerations available to contractors, Cannella recommends that contractors start planning their heating needs in July or early August. “By working with your dealer early, you can reserve the right size and type of heater, which can save you time and money.”

Changing Tides
For decades, heating needs were met with open-flame, direct-fired heaters. This technology delivered intense heat at the outlet and converted 100% of the fuel into heat, so contractors thought they were getting efficient heating. They allowed work to continue during the cold and were relatively inexpensive to operate, so many contractors were content.

However, there were some drawbacks to the technology, and moisture was 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 Cannella. This moisture can result in mold and bacteria growth when used inside an enclosed building. Worse yet, the water vapor can freeze and cause work delays within the structure.

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. “In some regions throughout Canada, insurance companies will not underwrite the use of open-flame heaters in certain operating conditions,” says Ed Jaroszewicz, director of Climate Technology products for Wacker Neuson Corporation.

Additionally, 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.”

For these and other reasons, indirect-fired heating units like the Arctic Bear™ Cub Series heating systems from Wacker Neuson have recently garnered much popularity. Employed at jobsites in Europe for decades, these heating systems have been prevalent on sites in North America for the last 10 years, and “inquiries for and sales of indirect-fired units have risen significantly over the last two seasons,” mentions Jaroszewicz.

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 unites can be safely positioned inside or outside an enclosed structure,” he adds.

Delivery not Intensity
The high intensity heat of an open flame heater quickly rises to the ceiling, creating uneven heat throughout the structure. While these units convert 100 percent of fuel to heat, it is an inefficient heat that requires 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. Large units like the Arctic Bear™ Cub 400 and 700 heaters pressurize the inside space for more efficient and faster heat up. They recirculate the air from inside the space through the heater and, when combined with thermostat controls, can help to reduce fuel consumption by up to 50 percent.

When sizing the heater for the space, a general rule of thumb is 1 to 3 BTUs required per cubic foot per hour, depending on the structure’s R-Value. Regardless of the technology used, the keys to selecting the right heating system are to start early and research the many options available from local dealers.

As an aid, available 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.