March 2004

Volume 13, Number 3

Toyotomi's Wall-Vented, Oil-Fired Space Heater

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Many of us living and working in parts of the country without access to inexpensive natural gas rely on fuel oil for heating. In the Northeast, for example, 36% of homes and 38% of commercial buildings are heated with oil. The Upper Midwest also uses a lot of fuel oil, while Alaska relies on both heating oil and kerosene. It was in Alaska in mid-2003 that I first saw Toyotomi’s high-efficiency, oil-fired space heaters.


The Toyotomi OM-22 is the first high-efficiency, wall-vented space heater that can burn heating oil.

Photo: Toyotomi U.S.A., Inc.

The Japanese company Toyotomi introduced its OM-22 oil-fired, pilotless, wall-mount space heater in the U.S. in 2001. It is designed to operate on No. 2 fuel oil or kerosene (No. 1 fuel oil) and relies on an external fuel tank (typically installed in a basement). Like Rinnai wall-mount space heaters, this is a through-the-wall-venting product with sealed combustion. The OM-22 has three output levels: 8,000, 15,000, and 22,000 Btu/hour. The efficiency, at 90%, is high for oil-fired heating equipment, and the combustion is relatively clean. According to Patrick Miller, of Nelson & Small, Inc., the distributor of Toyotomi products for the Northeast, the OM-22 vaporizes the fuel and burns the vapor, rather than directly burning the liquid fuel. A porcelain rod is heated electrically to initiate that vaporization. The unit uses 275 watts of electricity in the preheat mode and 46 watts during operation (primarily for the fan).

Researcher Dr. C. R. Krishna of Brookhaven National Laboratory, who studies fuel oil combustion, calls vaporization the “holy grail” of oil heating. If it’s done right, vaporization results in very low emissions of nitrogen oxides (NOx) and very low soot production, according to Krishna. Conventional oil combustion (sometimes referred to as “yellow-flame” combustion) involves “pressure atomization,” and it generally results in high NOx emissions. With “blue-flame” combustion, achieved through vaporization, emissions are significantly reduced. While Krishna was unfamiliar with the Toyotomi system, he said that manufacturers have long tried to perfect this type of oil combustion. Problems have included carbon deposits where the fuel is vaporized and carbon monoxide production if the flame becomes destabilized. If Toyotomi has solved these issues, the OM-22 could be a winner. Toyotomi could not provide EBN with NOx emissions data.

Home Energy Products of Belmont, New Hampshire has installed more than 300 of these units since 2001, says Dick Dargy of the company. He has been extremely pleased with the product. He has had zero callbacks due to equipment problems. “That’s amazing,” he told EBN. “With a new product like that, you always have problems.” He says Toyotomi did its homework through field testing before introducing it. “They’re really, really good,” he said. In fact, Dargy now heats his house with two of the units and has seen his heating bills drop in half so far this winter. He estimates that about 80% of their installations are being used with No. 2 heating oil; the other 20% use kerosene (primarily because kerosene was already being used in those homes).

As for maintenance, Randy Stone, the service manager at Toyotomi USA in Brookfield, Connecticut, recommends cleaning every one to two years. A small window lets you inspect the burner. Any carbon deposits will glow orange and result in flame that varies from the normal blue. Dargy says his company has so far found deposits in the equipment to be very light, though he recommends annual servicing. As for how clean the flue gases are, he says that he has white siding and, so far, there have been no soot deposits at all where the flue gases are vented.

The Toyotomi sells for about $1,200, according to Patrick Miller. Toyotomi USA says they have sold about 3,000 units since introducing the OM-22 in the U.S. Note that Toyotomi also produces and sells Kero-Sun unvented kerosene heaters, which EBN does not recommend. Unvented heaters are unsafe in any indoor application (see EBN Vol. 5, No. 3).

Toyotomi also produces an oil-fired demand water heater, Model OM-148. The product operates on either No. 2 heating oil or kerosene, relies on electronic ignition (no pilot light), burns at 88% efficiency, and produces 148,000 Btu/hour (43 kW). With a 60°F (33°C) temperature rise, the OM-148 can produce 4.0 gallons per minute (0.25 l/s); with an 80°F (44°C) temperature rise, the maximum flow rate drops to 3.0 gpm (0.19 l/s). For background on demand water heaters, see EBN Vol. 11, No. 10. – AW

For more information:

Toyotomi U.S.A., Inc.

P.O. Box 176

Brookfield, CT 06804


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March 1, 2004