To truly understand the benefits of automation features, whether it be the traditional bi-metal coil or up-and-coming electronic sensors and on-board computers, you need to have side-by-side tests with the automation on and off. Easier said than done. In Europe fully automated stoves - meaning stoves that you can "load and leave" - and the operator has no or limited control to adjust heat output, are already on the market. None are on the market in the US as there is no test method to certify them. The regulatory barrier to potentially far cleaner stoves from entering the US market is being addressed at the Collaborative Stove Design Challenge, where a automated stove testing protocol will be developed and submitted to the EPA.
Three major players in the US stove manufacturing community - Quadrafire, Travis and England Stove Works - now have automated systems to reduce start up and reloading emissions, which is one of the most important emissions issues that needs to be addressed. The Travis system uses electricity and is likely the most powerful of the three, and the other two don't need electricity. The England Stove Works stove has integrated their innovation in a very affordably price stove.
The real promise of automation is not to get a hot stove to hit an ultra-low particulate matter number in a lab, but to improve real-world performance by seamlessly optimizing performance throughout the burn cycle, to reducing start-up emissions and reducing emissions from unseasoned wood. EPA certification testing does not attempt to test these attributes of a stove, so stove companies have not had much incentive to invest a lot of time, effort and money to design for that.
In the United Kingdom solid burning heating devices are not classified by their size, i.e. stove vs. boiler, but 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., and much of it is imported from Europe. (Click here for PDF that includes this chart and some discussion of these issues.)
In November 2014, Brookhaven Lab will be testing automated stoves and prototypes at a stove design workshop to see how effective they are. Their designers aspire to be part of a real trend of cleaner, more automated residential wood heating. But can they do it at an affordable price point? And, are consumers ready for them? Here, we will look at stoves with automated features that are already on the market.
|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.
Nestor Martin’s Efel has an “automatic mode” that can keep the room at a desired temperature. Or 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.
|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.
The first five stoves described here represent American innovations that can partially reduce excessive wood smoke, while the last 2 stove from Europe represents a more holistic approach that can help reduce emission not just in the start up, but throughout the burn cycle. They are all still relatively new technologies and we are likely to see more companies improve upon them in coming years.