The Chimney Sweep Online Fireplace, Woodstove, Gas Stove and Barbecue Shop

Pacific Energy's EBT Technology

Q:
 I switched from a catalytic model to a Jotul 600F non cat stove. I'm really sorry that I did. They tell you of the comparable efficiencies and same total heat output from the non cat stoves, however what they don't tell you is that you will get all of the heat in the first 2 to 3 hours in the form of far more heat than you really want or need and the last 4 to 6 hours you have just remaining embers because most of the wood was used up in the initial burn. If you try to burn the wood at a more even usable temperature than you do not get the secondary burn and are creating a great deal of smoke up the chimney.

Gabriel Kochis

Hi Gabriel, Thanks for sharing! Your complaint is one we hear quite often about "size Jumbo" non-catalytic stoves, and especially about designs like the Jotul 600F, which have three door perimeters (door gasketing helps to control air leaks, but is far from airtight). The only company we know of that has solved the controllability issue in a 3-cubic-foot non-cat firebox is Pacific Energy, whose full-bead welded construction, single loading door and patented Extended Burn Technology (EBT) device combine to VASTLY INCREASE user control of the burn at all draft settings.

Like all non-catalytic EPA approved stoves, the 3-cubic-foot capacity Pacific Summit, Summit Classic , Alderlea T6 and Summit Insert rely on a secondary burn chamber to reburn the exhaust gases from the primary fire. In order for the fire in the secondary burn chamber to ignite and stay lit, a minimum firebox temperature must be maintained, which requires that an adequate supply of combustion air be available, even when the draft control is turned down to its lowest setting. To address this need, manufacturers of non-catalytic woodstoves typically incorporate a "stop" in the design of the air intake control, to ensure that adequate air enters the firebox even when the draft control is turned down as far as it will go. In larger fireboxes with bigger loads to burn, this "minimum" airflow to the fire can be considerable. This abundance of combustion air is delivered to the fire even when it might not be needed, and thus can cause faster than necessary fuel consumption during the other stages of the fire. The upshot of this situation can be shorter than optimum burn times, and frustrated stove owners who find that they often can't "hold" the fire as long as they might want between refuelings.

The EBT technology was designed to help maximize burn times for wood stoves with large fireboxes. It does this by delivering a burst of combustion air to the fire only as needed to maintain secondary lightoff temperature when the draft control is turned down far enough to create the longest possible burn.

Basically, the EBT device is a pivot plate which is mounted over a hole in the stove's primary air intake plenum so that it covers and uncovers the hole when it pivots. A bimetallic coil is attached to an actuator arm that pivots the plate so that when the firebox temperature indicates that more combustion air is needed, the coil expands, and the plate hinges open to uncover the intake hole and provide extra air to the fire. As the burn rate increases from the inflow of oxygen, the extra volatiles are consumed. Eventually, the fire stabilizes, the firebox returns to normal operating temperature and the coil contracts, lowering the base plate back down to seal the hole in the air intake plenum, without changing the original slide draft setting.

Here's another description, without the technical jargon. Let's say you live in an airtight house that has two slide-open windows in it, one operated manually and one automatically. You open the manual window enough to provide an adequate supply of air to your house, but not too much, or the place will be too drafty. As atmospheric conditions and other variables change, it is possible that sometimes your window is not going to be open far enough. If EBT technology was applied to that house, whenever the supply of air from your window opening wasn't adequate, the automatic window would slide open until the optimum ventilation level was achieved, then slide itself shut, returning control of the airflow to the manual window.

When EBT technology is applied to a woodstove, neither the manufacturer nor the operator has to worry about the manual draft control being turned down too low. If a situation looms where the secondary fire might become insufficient to consume the unburned volatile gases and particles from the primary fire, the coil senses the resulting temperature change and automatically hinges the pivot plate open to supply extra oxygen for as long as it takes to consume the extra volatiles and meet EPA emissions standards. This enables the stove to be operated at a truly "low burn" setting without fear of lost heat, excessive creosote formation or smoke pollution.

An Ideal burn cycle should heat the fuelwood to gasification temperature, cause the volatile gases to ignite in the secondary burn chamber (Stage 1), maintain the secondary fire at a sufficient level to consume the gases and unburned particulates from the primary fire and extract their heat value (Stage 2), then maximize the duration and heat productivity of the fire as it burns down to its final, charcoaling phase (Stage 3).

Here's how Pacific's EBT helps to achieve the perfect burn.

Finally, here's a video showing the EBT mechanism in action.

To return to the page you came from, use the < BACK button on your browser or click a button below:

The Chimney Sweep, Inc.
913 Harris Avenue
Bellingham, WA 98225-7032
1(888)-354-6722 toll-free in U.S. & Canada
1(360)-676-9080 FAX
http://www.chimneysweeponline.com

To send us E-Mail, Click Standard E-Mail Window or (our reply form)
Copyright © 1996 - 2008 The Chimney Sweep, Inc.