We define a fully automated wood stove as one where the consumer can "load and leave" and not have to worry about adjusting the air flow to get an optimum burn. On all traditional wood stoves, the consumer must adjust one or two levers that control the air. Often consumers don't do this well, resulting in poor combustion that fails to maximize efficiency or minimize smoke. Thus, even a brand new wood stove that performed very well in the test lab can perform very poorly in the hands of an inexperienced or inattentive operator.
|The Adventure series stoves were the|
first American-made automated stove.
|MF Fire, a small Maryland|
company is trying to disrupt
traditional stove technology.
The real promise of automation is not to get a hot stove to hit an ultra-low particulate matter number in a test lab, but to improve real-world results by seamlessly optimizing performance throughout the burn cycle, reducing start-up emissions, and even reducing emissions from unseasoned wood. EPA certification testing does not test for real-world performance, and incentive programs do not yet recognize the positive attributes of automated or semi-automated stoves, so stove companies have not had much incentive to invest a lot of time, effort, and money in developing them.
In Europe, fully automated stoves have been on the market for some time and are beginning to gain wider recognition from consumers and air agencies. Two companies have advanced automatic stoves that unfortunately are not available on the US market: The Danish company Hwam, who developed the Autopilot IHS, and Austria's Rika, who developed the Rikatronic. In the United Kingdom, solid burning heating devices are classified by whether they are automatic or manual. To achieve a rating to be used in more polluted areas, manually operated stoves must submit lab tests showing 5 burns for each output level because “manually controlled appliances show much higher variation between tests.” Automatic appliances only have to be tested 3 times at each output level. The chart below shows a wide variety of technology that exists in both stoves and boilers in Europe, but only exists in boilers in the U.S. (Click here for PDF that includes this chart and some discussion of these issues.)
In 2013 and 2014, the Alliance for Green Heat partnered with Brookhaven National Lab to assess and test automated stoves and prototypes at stove design competitions. Their designers aspire to be part of a real trend towards cleaner, more automated residential wood heating. But can they do it at an affordable price point? And, are consumers ready for them? Here, we look at stoves with partially automated features that are already on the market.
Partial automation solutions
|A bi-metal coil acts as a heat-|
sensitive thermostat which can partially
control the opening and closing of the damper.
|The rotating trigger mechanism in the|
Smartstove Collection by Englander
reduces air flow once the stove is hot.
|Quadrafire's Explorer 2 Start-Up air|
control helps give the stove more
air in the first 25 minutes.
|The slider on the Cape Cod |
adjusts the rate of burns.
Remote operation. A remote control device does not necessarily provide any automation to the air flow. It can just allow you to do it manually from the couch. However, some like the Nestor Martin’s Efel has a partial “automatic mode” that can keep the room at a desired temperature. In timer mode, it can adjust the room temperature at a pre-set time. The stoves uses a simple ambient air thermostat in a remote control device that you can operate from the couch or anywhere nearby. If you don’t use it in automatic mode, the remote control allows the user to adjust the intensity of the fire just as you would with a manual air control. One of the key things that distinguishes this Efel from truly automated stoves is that there are no sensors in the stove that can prevent the stove from smoldering or override an adjustment by the operator that would make the fire smolder.
|HWAM's Autopilot technology uses|
sensors, along with a bi-metal spring to
regulate combustion temperatures.
1. The final two stoves are more fully automated stoves and are on the market in Europe, but not in the US. Danish company HWAM has integrated a new patented system: Autopilot. Along with the Austrian Rikatronic, described below, the Hwam is one of the most advanced and fully automated stoves in Europe. HWAM 3630 IHS features a control system that electronically measures combustion conditions through the use of a lambda oxygen sensor and a thermocouple. An onboard computer then allocates combustion air through three separate valves to help the consumer achieve the same results at home that are obtained in test labs under ideal conditions. According to the Danish Technological institute, HWAM stoves with this system are 17% more efficient and produce 40% more heat.
|Rikatronic has a microprocessor-controlled |
motor and a flame temperature sensor
which drives the RLS air distribution system.
The light tells you the optimal time to reload.
By pressing the button, the stove knows
it has fresh wood to handle.