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U.S. Army Soldier & Biological Chemical Command
U.S. Army Soldier Systems Center-Natick
Public Affairs Office
Kansas Street
Natick, MA 01760-5012

Contact: Chief, Public Affairs Office
(508) 233-5340

Date: September 25, 2001
No: 01-52

New space heaters increase safety and efficiency

Natick, Mass. --- Two additions to the Army's Family of Space Heaters will be available for unit fund purchase through Defense Supply Center-Philadelphia for the fiscal year 2002 heating season.

Introduced in 1992, the lineup of heaters was developed at the U.S. Army Soldier Systems Center (Natick) to replace outdated potbelly and Yukon heaters, and eliminate safety hazards and operational inefficiencies associated with them. They ushered in the latest advances in combustion, power generation and microprocessor technology to provide comfort and protection for soldiers, supplies and equipment in tents during cold weather operations in the field.

"One of the unique characteristics of these heaters is operation without electrical power," said Joe MacKoul, project engineer. "Most of the commercial heaters require electrical power."

Compared to commercial heaters, all military-designed heaters can operate on multiple fuels in severe cold and under rugged field conditions. They're rapidly portable and have a vented exhaust.

MacKoul, along with Ali Bayou and Brad Volz, compose the Heater Team at Natick's Product Manager-Soldier Support. Joining the Space Heater Medium and Space Heater Arctic this year are the Space Heater Small and Space Heater Convective. Along with the others, the two heaters were designed for specific needs and should be a welcome sight on frosty days.

Convective heat
Pumping out 35,000 BTUs, the Space Heater Convective yields plenty of hot air running on various liquid fuels. Unlike the other Army space heaters, the Space Heater Convective requires electricity, but it's self-produced through an internal thermoelectric generator.

"The heater is the first of its kind in the world that provides forced hot-air circulation without the need of an external or engine-driven power supply," MacKoul said. "Electrical power to operate the Space Heater Convective is generated internally and without any moving parts by the use of thermoelectric modules, located in the combustion chamber, that convert excess heat into electrical energy."

It's the same technology used in the Family of Space Heater's thermoelectric fan and produces the same benefits. When the thermoelectric fan is placed on an operating Space Heater Medium or Space Heater Arctic, a module triggers the generator to spin a fan that circulates warm air to the lower regions and corners of a tent. It helps solve the problem of hot air collecting near the ceiling. The Space Heater Convective thermoelectric modules generate 200 watts of power for the blowers, pumps, and ignition and safety systems.

The Space Heater Convective is intended for use with the Modular Command Post Systems, Tactical Operation Centers or other tents housing costly electronic equipment, channeling heat into the tent through a flexible duct. A single switch on a palm-sized controller connected to the heater turns it on and off. Operation is completely automatic because of built-in diagnostics, safety and temperature controls.

An intelligent control box tells soldiers if there is a problem and how to fix it. A shut-off sensor is activated if the heater is tipped over.

"Soldiers don't need to handle fuel or be on fire guard. It's a more precise heater, and it's more affordable in this application," MacKoul said.

The heater increases combustion efficiency 60 percent over currently fielded nonpowered heaters and burns diesel fuel more cleanly, which saves fuel and reduces maintenance, he said. It weighs 70 pounds and is operational between minus 60 to 60 degrees F. Accessories include remote temperature control box, cable, insulated air ducts, fuel hoses, gravity feed adapter, fuel can stand and spare parts.

Heater that fits
A gap existed in the Family of Space Heaters for heating the Soldier Crew Tent and other small tents until the Space Heater Small was designed.

"Current heaters were too large. They put out too much heat and were too cumbersome for that space," said MacKoul.

The Space Heater Small puts out 12,000 BTUs, operates without electrical power and uses a new vaporizing S-tube burner technology.

The new vaporizing burner technology, used by the larger heaters as well, overcomes the major combustion and safety problems plaguing the nonpowered heater industry the past 50 years.

"In the old days, fuel would pool in the bottom of the burner pot to be vaporized and burned. If fuel entered faster than it could be vaporized, the burner would flood and you would end up with a 'runaway' heater," MacKoul said. "At that point there was no way to control it."

The new improved and patented burner design uses a tube that fills with no more than 20 cubic centimeters of fuel before a switch cuts off further supply. The tube eliminates exposure to raw fuel during operation and the possibility of flooding the pot, and provides a multi-stage liquid to vapor combustion process resulting in much cleaner, safer burning of liquid fuels. Besides being safer, fuel is conserved and maintenance is easier.

"I've seen a stack completely plugged up with soot in the old heater designs," said MacKoul.

The heater has an integral fuel tank that eliminates the need for hoses, gravity feed adaptor, fuel can stand and fuel can, but it can be connected to an external tank for prolonged use without refueling. A smoke stack collapses and fits into the heater for compact storage, and total set-up time takes about five minutes, according to MacKoul.

The Space Heater Small weighs 20 pounds, is completely self-contained and functions in temperatures of minus 60 to 60 degrees F.

Be wary of exhaust
Fire will certainly capture a soldier's attention, but more sinister is the silent danger of tent heaters that improperly ventilate their combustion byproducts. Many commercially-available heaters powered with propane or kerosene allow all of the exhaust to escape directly into the living space, which is harmful or potentially lethal, said Joe MacKoul, project engineer for the Army's Family of Space Heaters.

"Being (unit-purchased items), soldiers may not want to buy what appears to be a more expensive military heater," he said. "But you would need to buy several commercial heaters to get the same heat output.

In addition, soldiers would also be required to purchase several hazard monitoring devices such as carbon monoxide detectors and alarms to help mitigate the risk. In the end, it's not cheaper to buy the commercial heaters, according to MacKoul.

The U.S. Army Center for Health Promotion and Preventive Medicine recommends avoiding commercial tent heaters, and the U.S. Consumer Products Safety Commission advises against using unvented kerosene heaters while sleeping in enclosed areas, such as tents.

Military heaters have venting and heat output appropriate for the tent size. They are rugged, operate with multiple fuels and are effective at lower temperatures. Although convenient, non-military heaters aren't worth the expense.

"Purchase of commercially-available unvented heaters for field use is unjustifiable from a safety, economic and performance perspective," MacKoul said.

Natick is part of the U.S. Army Soldier and Biological Chemical Command (SBCCOM). For more information about SBCCOM or the Soldier Systems Center (Natick), please visit our website at