By Bill Sendelback

A brand new entry into the wood stove wars of North America is the first wood stove to be certified by the Environmental Protection Agency (EPA) to its 2020 New Source Performance Standards (NSPS) emissions standard tested with cordwood. The Kiwi VcV 2.1 model wood stove from Eco Vision, Aukland, New Zealand, was EPA certified in early May with a weighted average emissions rate of 1.3 gph, beating the EPA’s 2020 particulate emissions limit of 2.5 gph when tested with cordwood.

Filter set being heated during test.

The 2.1 cu. ft. firebox is rated at 77.2% overall efficiency with heat output ranging from 12,800 to 28,800 Btus. Low burn emissions are 0.74 gph, and low burn efficiency is 79.9% with burn times as long as 14 hours.

The Kiwi VcV 2.1 model was in development for the last four years by Ben Myren of Myren Consulting, Colville, Washington, after contracting with Eco Vision. EPA testing was done by Dirigo Laboratories, Clackamas, Oregon.

“What is clear is that the EPA standards for cordwood are not only reasonable but are achievable,” according to Brian Gauld, CEO of Eco Vision. “We hope this breakthrough will go a long way toward the industry coming on board with cordwood testing as a better way of making sure our wood stoves achieve the lowest emissions and the highest efficiencies possible when used in our homes.”

The patented technology features a “Venturi-Controlled Valve” (VcV) requiring no electricity or electronic controls. Unlike bi-metallic coils used to control wood stove burns since the 1980s – in wood stoves such as The Earth Stove – the Kiwi VcV 2.1 relies on discs in a venturi moving up and down, with the static pressure of the fire venting to regulate the burn.

“Bi-metallic coils are slow to react since they rely on heat that first has to go through the stove,” according to Myren. “The VcV technology interacts almost instantaneously with the stove to control the burn. The consumer can load the stove, close the primary air control to the low-burn setting, walk away and let the stove control itself. Even though the VcV is entirely mechanical, it has kind of an automatic feature, but no electronics are required. It is extremely user friendly, and takes some of the ‘idiot’ out of stove operation.”

While wood stoves traditionally have been emissions- and efficiency- tested burning crib fuel, specifically engineered and constructed wood testing fuel, the 2015 NSPS now allows manufacturers to request of EPA the option to have wood stoves tested with cordwood, which is similar to the fuel burned by consumers.

“We think it’s obvious that EPA testing will transition from testing with cribs to testing with cordwood in the hope that stove testing with cordwood will perform better in the field than stoves tested with crib fuel,” says Myren, “so we thought it a smart move to do our certification testing now with cordwood.”

When testing with cordwood, the procedures include cold starts, says Myren, while when testing with cribs, testing starts with a warm stove. “This makes a huge difference,” he says. “Stoves testing with cordwood have to perform well even when cold.”

“Our wish is to license the VcV technology to an existing manufacturer in North America, and we are in serious discussions,” says Gauld, “so at this time we have no intention of manufacturing ourselves.”