Think Warm Thoughts

by John G. Smith, Technical Correspondent

TORONTO, Ont. – It’s hard enough to scrape together the cash to invest in new equipment, but when the government is willing to help pay off the final bill, it should be enough to make you think warm thoughts.

Through Natural Resources Canada’s Commercial Transportation Energy Efficiency and Fuels Initiative, the federal government will pay 20 per cent of the cost of an approved supplemental heater – up to a maximum of $350 – as long as the device is brand new and can measure the amount it’s used over a two-year period.

It’s an investment that can quickly pay dividends. Based on the findings of an idling study by U.S.-based Argonne National Laboratory, a fuel-fired bunk heater can help reduce a Class 8 truck’s fuel consumption by 2.2 to 3.7 litres per hour for about 1,450 hours per year.

But the advantages aren’t limited to lower fuel bills – particularly if you consider the costs of fines associated with anti-idling legislation.

“The fines are astronomical,” says John Dennehy, Espar’s vice-president, marketing. “Let’s take New Jersey, for example. Your first offence is US$850. You’ve just bought a heating system (for that price). The second fine is $5,000.”

While Canadian trucks have dominated the use of the heaters in the past (it is, after all, a little colder up here), U.S. truck owners are picking up the pace. And depending on the supplier you talk to, between 10 and 15 per cent of North America’s heavy trucks now tend to have the equipment.

“I would say that there’s a much larger penetration to come over the next few years. Fuel prices aren’t coming down any…and we’re hearing about more idling fines,” says Webasto’s Don Kanneth.

Excessive idling is also being discouraged in Canada. Natural Resources Canada is in the midst of its third annual “Idle Free – Quiet Zone Campaign” at national truck stops to help encourage truckers to shut down their engines whenever possible. And 82 truck stops are now participating in the initiative.

Choosing your weapon

When choosing a bunk heater, it’s important to consider the size of your cab and the climates through which you’ll be running, says Espar engineering technologist Don Handsor.

While a 7,500-btu unit will easily heat both bunks in a mid-rise sleeper, those driving the largest “condo” designs might want to consider higher outputs – particularly if they’re travelling north for extended periods of time. (Or consider spec’ing a truck with an arctic package that includes additional insulation, Handsor says.)

“We find the 80/20 rule. Eighty per cent of the time, a 7,000 btu (unit) will work very well. Occasionally we get someone who prefers a more robust product,” Kanneth says. Specifically, if you’re regularly spending the night in -30C or -40C conditions, you’ll probably want a 12,000-btu model.

But it’s also important not to spec’ a unit that’s too large. A heater should be expected to cycle between its medium and high setting for the majority of the time to ensure the maximum level of efficiency, Handsor explains.

Maintenance matters

Bunk heaters tend to be relatively trouble-free, but there are still maintenance issues to consider.

The devices can overheat if vents are blocked by something such as a piece of luggage, Handsor says, referring to the need to ensure a steady flow of air. Meanwhile, it’s important to leave about two inches of space around the heater’s housing, to ensure the unit can breathe.

But one of the most important maintenance practices involves running the heater during the summer season.

“We recommend, regardless of the temperature zone a driver is going through … that they run the heating system for 15 minutes per month through the summer months,” says Dennehy.

The practice ensures the heater is able to draw on a fresh supply of fuel, clearing the system of any deposits or wax, he says. “The more the heater runs, the better it will perform.”

Of course, diesel isn’t a bunk heater’s only source of power, and Handsor recommends regular inspections to ensure that electrical wiring hasn’t been crushed or damaged, and that battery connections don’t show any signs of corrosion.

“Make sure the batteries are clean and up to spec,” he adds.

It’s also important to be careful when tossing tools and supplies under the bottom bunk, where the heaters will typically be located.

“The heaters are pretty rigid, but it’s the duct work that can get crushed,” Dennehy says.

Once that happens, a heater can overheat and shut down. (At that point, the Espar heaters will shut down for four minutes before they can be restarted. If two more attempts to restart the unit fail, the system is locked and will have to be re-set with a mechanic’s diagnostic tool.)

Most competent do-it-yourselfers should be able to install their own bunk heater in four to six hours, he adds. “We have a half-hour installation video that is available that gives you an overview. It’s a step-by-step instruction.”

But practice makes perfect. You’ll want to compare your investment of time to the fact that experienced installers can have a unit in place within two hours.

Trucks running in Canada and through the northern U.S. will tend to see a return on the investment in a bunk heater within a year.

A 7,800-btu unit, for example will run about 24 hours on just under four litres of fuel. “You might get a week out of that,” Handsor says.

In comparison, says Dennehy, a Class 8 truck idling at 900 rpm will use the same amount of fuel every hour.

“We’re even seeing paybacks in just three months,” Kanneth says, and all paybacks are becoming quicker in the face of escalating fuel prices.

Meanwhile, there’s no question that modern fuel-injected diesel engines will start more easily than their predecessors, but an argument can still be made for spec’ing coolant heaters as well.

“What’s not been perfected is the wear and tear on that engine for each cold start,” Kanneth says, noting the damage is equivalent to what you would see after driving 480 kms.

And he counts a cold start as anything below the freezing mark.

Changing technology

“The biggest change that I have seen over the years is people starting to get away from the larger amperage draw, higher wattage heaters,” Kanneth adds. The company’s 7,000-btu furnace will draw an average of 1.5 amps compared to past combined bunk and coolant heaters that required 10 amps. (The devices are now offered as separate units instead.)

The low power requirements are particularly important given the parasitic loads on a modern truck, he says. “(Truck owners)want the cooler to keep the sandwich and soda pops cold; they want a TV.

“And in winter, you lose 50 per cent reserve capacity in the battery once you hit (the freezing) mark,” he adds.

Information about Natural Resources Canada’s FleetSmart program – and rebates for supplemental heaters – can be found on the Internet at

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