Meet the Teams: A New Zealand entrepreneur automates the wood stove - without using electricity

This post is the first in a series of technology and innovation blogs introducing the 12 teams participating in the 2018 Wood Stove Design Challenge in November.

By John Ackerly and Shoshana Rybeck, Alliance for Green Heat 

Alistair Gauld with the VcV stove. 

Variable Choke Venturi (VcV) technology has come a long way from New Zealand, where it was invented over a decade ago. It is a clever, simple device to improve combustion in wood stoves that is reliable and does not require electricity. Brian Gauld, an accountant in New Zealand, met the VcV inventor and bought the rights to it, convinced that it held the secret to cleaning up manually operated wood stoves.  

The VcV is a valve controlled by the draft generated by the stove when burning, but making it work effectively on a wood stove and then getting that stove certified was a much longer journey than Brian initially expected. There is a huge need for an automated, “idiot proof” stove in New Zealand, but the market is not big enough to justify the costs so Brian set his sights on the North American market. In 2008, he hired Ben Myren to help integrate the VcV valve into a stove. So began one of the most innovative and promising new stove technologies on the US market.

The Promise of the Technology

Simply put, the valves increase or decrease the amount of combustion air entering the stove in response to static pressure changes at any given time, depending on how much combustion air the stove needs. Ben and Brian realized that by combining two VcV valves—one for primary air and one for secondary air—the VcVs could reduce particulate matter (PM) emissions even more, hoping that would be the key to reliably meeting the EPA’s 2020 standards. Brian and Ben were well on their way to building an automated stove without electricity, whereas other automated stove designers were trying to do the same thing with sensors, electronics and computer chips. The marketplace for wood stoves has a lot of folks who dislike the thought of a wood stove that needs electricity to operate. The simplicity of the Flamekeepers’ technology could go a long way to ensuring that the stove would not just operate well in the lab, but also in the hands of the average consumer. And that has been the great challenge of the wood stove since it was invented years ago.

Labeled diagram of on a VCV valve

From the moment the consumer lights the stove, they can shut the door, sit back, and enjoy the heat until it needs to be reloaded, according to Ben Myren. At the time of ignition, the second VcV is engaged, as explained in an illustrative informational video on the model. The Secondary VcV (S VcV), a disc attached to the secondary air inlet, rises and falls relative to static pressure, which increases and decreases with the amount of combustion taking place in the firebox. The S VcV functions all the time and supplies just enough secondary air during a burn to maximize combustion efficiency. Once the static pressure decreases at the end of the burn and more oxygen is needed to increase combustion, the P VcV disc goes down again. 

While most automated stoves and stove prototypes include a temperature sensor to help regulate air flow, thermometers require electronics and a control board which can be to be deceptively complicated and unhelpful to control combustion. Instead, static pressure can be a more reliable way to control what goes on inside the stove and what goes up the stove pipe. Ben says that temperature measurements can often be misleading when determining a stove’s combustion level and oxygen needs. 

When people hear about how the VcV works they think that it is very similar to a bi-metalic coil, which responds to heat, and closes down an air inlet as the stove gets hotter. Bi-metalic coils have been used for decades and a few manufacturers still use them even though they can be unpredictable during the lab certification process. Bi-metalic coils respond to heat, whereas the VcV responds to static pressure. While heat must move from the firebox to the coils, any change in combustion will automatically change the airflow, thus inciting an immediate VcV response. Therefore, Ben credits VcV technology with being far more efficient and simply better than a bi-metalic alternative. 

Advantages of Simplicity 

EPA test stove on scale with test filters 

being preheated in the background.

The simplicity of the VcV comes from the concept of letting the stove’s combustion determine its air flow needs at any given moment, which inherently reduces the operational errors. While the user may set the stove to a burn setting that is too low, the disc technology will not lift until the combustion, as determined by the static pressure, is at a high enough level to safely cut off the air flow. The stove will eventually go to that low setting, but not until the static pressure indicates the time is right. Therefore, consumers have the autonomy to choose the burn level they want, but the stove will only reach that level when it is able to do so cleanly. Ben also added a catalyst to the stove to ensure that it would operate well under 0.5 grams an hour and meet the 2020 EPA cordwood emission limits.

Brian and Ben also recognized and addressed one inherent problem in stove installations all over the US: varying heights of chimneys. The engine of a stove is its chimney, which creates a natural draft to pull both the primary and secondary air into the stove.  But homes can have chimneys anywhere from 10 to 30 feet high, which dramatically impacts combustion, and stove manufacturers have no way to address this as they build to the height of the chimney in the test lab—which is 14 to 16 feet. Brian and Ben realized that they could fit the VcV with heavier or lighter discs so that the stove could work well with any chimney height.  

At least one North America company has applied for licensing of the VcV technology and a stove with the VcV may also be licensed in New Zealand.  

Team Goals

Brian and Ben are no strangers to the Wood Stove Design Challenge. An early prototype of the stove competed in 2014. These prototypes showed great promise and led to the stove being the very first North American wood stove to be tested and certified with cordwood.

Ben Myren lighting a stove at the
2013 Wood Stove Design Challenge

Brian’s son Alister Gauld is also a part owner of the company and will be in Washington in November when the stove will be put through its paces by professional stove technicians to see whether it performs as designed. While Ben and his lab tech Eric Schaefer were just hired by Brian on a daily basis and have no financial stake in the company, they are proud of helping to develop the first non-electric automated stove in North America that can help clean up our air-sheds far better than stoves that can be left to smolder by their owners. The beauty of the VcV is that the owner doesn’t even have to know how it works inside or that it is a groundbreaking stove. From the outside it will look exactly like a traditional stove that will keep the house warm in a power outage.

Contact the team

Brian Gauld

brian@thevcv.com

Ben Myren 
myren.ben@gmail.com

Alistair Gauld
Alistair@harts.co.nz

Eric Schaefer

ericsschaefer82@gmail.com

Meet the Contestants; Firemaster

With the first Wood Stove Decathlon only a few months away, we are doing a weekly blog post to showcase the Decathlon competitors. Take this opportunity to learn more about the teams and their stove’s innovative features.

Jason Stewart is bringing a stove to the Decathlon with a new feature that he thinks can help clean up thousands of older stoves. The IntensiFire is a down draft insert that can be retrofitted to nearly any wood stove. The down draft redirects unburned gases back into the hot coal bed, to reignite and save heat. This also makes more efficient use of the fuel. And, a more complete combustion of the smoke also helps to reduce emissions by burning smoke particulates that otherwise would have been released into the atmosphere.

The insert is much cheaper to manufacture and to install compared to the price of a complete wood stove. Its versatility to be retrofitted to multiple styles of wood stoves makes the Intensifire a viable option in many situations.

Stewart found himself in such a situation with an old wood stove that supposedly was to heat his rental home. The old clunker smoked badly, with wasted heat rising up the flue. The landlord wouldn’t replace it and Stewart was not allowed to make any major modifications. With some tinkering, Stewart simply extended the flue into the firebox to create a down draft. It worked so well, Stewart was able to increase up to 60% of the old stove’s heat efficiency. The success of his invention surprised perhaps even himself, and Stewart decided to pause his pursuit of an Architecture Degree and start the IntensiFire business.

Several models later, Stewart is gearing up for the Decathlon and expanding his market to the United States. This further extends Stewart’s commitment to protecting the environment. In 2009, he sailed around New Zealand as a volunteer on Earthrace, a boat run on biodiesel, to highlight important environmental issues. The next year, he once again boarded Earthrace, renamed Ady Gil, to oppose Japanese whaling.

The biggest issue opposing Stewart now is the financial costs to attend the Decathlon. Stewart must ship himself and his IntensiFire from New Zealand to Washington DC.  If you are able to help Stewart reach his goals, he can be contacted here.

We are looking forward to seeing IntensiFire in action at the Wood Stove Decathlon November 16-19, 2013. Vote for your favorite stove at Popular Mechanics.

The U.S. and Australia have Similar, but Distinct, Stove Regulation Strategies.

Australia is in the process of developing stricter emission standards for wood heaters and their approach is a fascinating glimpse into another regulatory culture. The strategies and cost – benefit analysis in Australia should be a valuable comparison for the EPA as it finalizes its New Source Performance Standards (NSPS) for US wood heaters. This post is an overview of an Australian report showing the financial gains created by stricter regulations on wood heaters.

In 2011 the Council of Australian Governments (COAG) identified air quality as a Priority Issue of National Significance and agreed that the COAG Standing Council on Environment and Water (SCEW) would develop a National Plan for Clean Air to improve air quality, and community health and well being, to be delivered to COAG by the end of 2014. The first stage of the National Plan for Clean Air will focus on particle emission reductions and a consultation Regulation Impact Statement which assesses alternative policy options that could be employed to reduce emissions from wood heaters in Australia, and establishes their relative costs and benefits.

The current Australian Standards that cover wood heater emissions and efficiency set a criterion of 4 grams of particulate matter (PM₁₀) per kilogram of fuel brunt (4g/kg). There is currently no efficiency criterion, but efficiency results must be reported on a label permanently attached to the appliance.

The report showed a large range of potential policy measures that could be implemented to reduce emissions from wood heaters. The potential measures fall into three major categories:

• wood heater design or performance standards;
• measures to promote compliance of retail models against these standards; and
• measures influencing the in-service operational performance of wood heaters.

These measures could be delivered through a range of policy 'vehicles'. The policy delivery approaches examined are a voluntary national program, a collaborative approach or a national regulatory approach.

Under the business-as-usual or 'base case' scenario, particulate emissions from wood heaters in Australia are expected to fall by around 5000 tons (or 12%) over the next twenty years, as old heaters are progressively replaced with new, lower particulate emitting heaters. The reduction in annual particulate emissions from wood heaters under the policy options examined, over and above the business-as-usual reductions, range from 3% to 18%.

The estimated costs to government of implementing the different policy options range from $15 million over the next twenty years to around $39 million. The estimated costs to manufacturers range from $240,000 to $17 million, the strictest boasting an efficiency standard of 60% as well as an emission limit of 1.5 g/kg. The health benefits of the options are estimated to range from $760 million to around $1,850 million over the twenty year assessment period. Although the greatest emission reductions are estimated for the most expensive option, the highest health benefits are estimated for another which has a shorter phase-in period for the new standards. The estimated benefits far outweigh the estimated costs of all options included in the analysis. The present value of the net benefits range from around $750 million to $1,800 million.

The report concludes the greatest net benefits are likely to be achieved via a national regulatory approach for managing wood heater emissions, rather than through a voluntary or collaborative approach. This could be achieved either through a Commonwealth regulation, a National Environment Protection Measure (NEPM) or through mirror legislation.

View the full report here.

New Zealand Study Finds Wood Pellet Heating Improves Health for Low-income Families (excerpts)

Last week in New Zealand, the Productivity Commission released a Housing Affordability Report.  The report included a review of a housing, insulation and health study involving 1,400 households from seven regions. It showed dramatic health improvements brought about by interventions such as replacing inefficient electric heaters and unflued gas heaters with heat pumps, wood pellet burners and flued gas heaters. These positive effects were more marked for low-income families. 

In New Zealand, excess moisture is a major problem leading to mold and ill-health effects and the dry heat produced by pellet stoves was an excellent remedy.

One of New Zealand's leading researchers on inequality in health and housing, Philippa Howden-Chapman, pointed out that the lowest income families spend about 13 percent of their income on heating, while the wealthiest only about 2 percent. Around 1600 extra people die in winter than in summer due to poor housing and a lack of heating.

Lack of affordable housing and heating is not a new phenomenon.  Two thousand years ago a pregnant woman and her carpenter husband could not find adequate or affordable lodging, and the woman had to give birth in a manger. 

For the full story:

http://www.stuff.co.nz/nelson-mail/opinion/columnists/teresa-o-connor/6173976/Stressmas-rams-home-key-themes