The Sensor Surge: Why Equipment Engineers Are Adding Sensors Everywhere — and Why the Wood Stove May be Next

MF Fire is the US industry leader in
integrating sensors into wood stoves

Over the last decade equipment engineers have been rapidly adding sensors to cars, HVAC systems, laundry machines, refrigerators and other household appliances. That trend isn’t just about bells and whistles — it’s driven by lower sensor costs, smarter processing at the edge, connectivity, regulatory and efficiency pressures, and real customer value. Below is a concise look at the benefits, the sensor types being deployed, why prices are falling, where the trend is headed, and how this sensor wave will likely soon be more widespread in something old-school: the wood stove.

Sensors have slowly started to enter the wood stove technology space and are catching on in Europe much faster than North America.  In the US, the Baltimore-based MF Fire made an after-market device with funding from the Department of Energy that represents the most sophisticated use of sensors for wood stoves.  At least one big European stove brand, Jotul, with a major footprint in the U.S. are releasing stoves with automated combustion control only in the European market. 

In 2025, Ecodesign suggested that automated combustion control (ACC) should become mandatory on all new stoves, a suggestion that presumably comes from studying the Blauer Engel (Blauer Engel, 2020) certification. This sent a kind of a shockwave through the stove manufacturing industry, and resulted in industry pushback.  The Nordic Ecolabelling system, representing five countries, is considering requiring ACC in new stoves, or other technology innovation. 

According to a 2025 report from Nordic Energy Research, "In Europe, fully automated stoves have been on the market for some time—for example, RIKA (AU) since 2007 (RIKA Rikatronic, 2025) and HWAM (DK) since 2012 (HWAM, 2025)—and are beginning to gain wider recognition amongst consumers and distributors. The Rikatronic technology (now Rikatronic4 as the latest version) was introduced by RIKA of Austria in 2007; it integrates temperature sensors and electronics to control the air supply and advises when another wood log should be put on the fire through a light visible at the front of the fireplace. This seems to be the most advanced technology for a batch fed or manual wood log burner in terms of automating the reloading and ensuring optimum firebox temperatures for reducing emissions."

There are now more than 10 wood stoves with ACC on the market in Europe, with many in the range of US$2,500 - $4,000.  The best selling automated stove in the world may be the Connect 556 made by Contura a major Swedish stove manufacturer.  Once wood stove certification tests become stricter than they are today in the US and Europe, automation is likely to be the safest way to pass the tests.  Otherwise, the inherent variability in combustion in manually operated stoves will not leave any comfortable margin to passing emission tests.  Currently, stove certification labs on both continents have been able to develop the expertise to pass emission tests without hardly any record of stoves failing the test.

European retailers are also starting to advertise the benefits of automated stoves, socializing the technology benefits to consumers, retailers and the wider community concerned about the health impacts of residential wood smoke. But wood stoves still lag far behind other heating and combustion devices when it comes to embracing the adoption of more and more sensors.

It is important to distinguish full automation in wood stoves from partial automation. Full automation means that the stove has no lever for the operator to adjust air flow, unless the onboard computers can override and optimize the stove for emissions, before responding to the user adjustment for more or less heat. With partial automation, the stove still has a lever or handle to adjust airflow, and the stove has some technology to make minor adjustments in air flow.  The bi-metal coils in Blaze King stoves could be considered partial automation, along with the valves in Pacific Energy Neo stoves. Partial automation, often achieved with the need for electricity, appears to only offer minor benefits compared to fully automated stoves.

Without automation, there is
virtually no way to predict the
performance of a stove 
once it leaves the lab.

Air quality agencies in the U.S. – from the EPA, to NESCAUM to state and local agencies – have been focusing on the shortcomings of the certification process and on designing a better testing protocol.  But US institutions are far behind Europe in studying and promoting automation in stoves.

One of the most obvious benefits of ACC is to prevent overnight smoldering along with speeding up the start-up of the stove. But it may be the safety aspects – producing less creosote and safety sensors that offer peace of mind to homeowners (and insurance companies) that will drive innovation.

From 2013 – 2023, the Alliance for Green Heat ran a series of Design Challenges with the Brookhaven National Lab, and funding from NYSERDA, the Department of Energy and Osprey Foundation that sought to accelerate research and production of automation in wood stoves. Some of the contestants, such as MF Fire, have gone on to get that technology into the marketplace with the Fire MAPS Smart Fire Assistant. 

Why sensors are being added:

• Improved safety: early detection of hazards (overheat, leaks, CO) reduces fire and poisoning risk.
• Energy efficiency and emissions: feedback lets systems run only as hard as needed (modulating burners, variable fans).
• Predictive maintenance: sensors spot component wear and anomalies before failure, lowering downtime and service costs.
• Better user experience: remote monitoring, diagnostics, adaptive settings, and automated schedules.
• Regulatory and reporting needs: emissions, indoor-air-quality (IAQ) monitoring, and energy reporting demand measurement.
• Data-driven product improvement and new services (e.g., subscription performance monitoring).

The use and benefits of sensors are different for each
application based on the risks that application faces.

Common sensor types now used in consumer equipment

• Temperature sensors (thermistors, RTDs, digital temp ICs) — ubiquitous in HVAC and appliances.
• Pressure sensors — used for refrigerant systems, combustion chambers, and airflow measurement.
• Humidity sensors — for IAQ, laundry cycles, and HVAC control.
• Gas sensors (CO, CO2, O2, NOx) — safety and emissions control in furnaces and cookers.
• Particulate sensors (optical/laser) — measuring PM2.5/PM10 for IAQ and emission controls.
• Flow sensors (air and liquid) — ensure correct ventilation, fuel, and coolant flow.
• Vibration and accelerometers — detect mechanical faults in compressors, pumps, motors.
• Current and voltage sensors — monitor electrical health and detect stalled motors or short circuits.
• Optical and camera sensors — visual inspections, flame detection, and product state recognition.
• Position and angle sensors — actuators, dampers, and valve control.

The steady growth in the use of sensors is driven by
safety, consumer appeal and benefits to manufacturers. 

Why sensor prices are falling

• MEMS and semiconductor scaling: MEMS fabrication and CMOS integration drive down unit cost and size.
• High-volume consumer markets: smartphones, wearables, and automotive volumes subsidize production for other markets.
• Integration: multifunction sensor packages combine temperature, pressure, humidity, and motion on a single die, lowering BOM cost.
• Standardization and modularity: off-the-shelf sensor modules and cloud-friendly firmware speed integration and reduce engineering cost.
• Wireless and low-power tech: cheaper connectivity (BLE, LoRaWAN, Thread) reduces installation complexity and cost of retrofits.

Is the trend likely to continue? Yes. Expected drivers:

• Continued unit-cost declines and richer sensor fusion capabilities.
• Edge computing and tiny ML: more intelligence on-device reduces data bandwidth and privacy concerns.
• Stricter efficiency and emissions standards worldwide.
• Growing consumer demand for smart, connected products and services.
• OEMs monetizing data and offering remote service/subscription models.

Expect more sensors per device, tighter integration with controls, and better diagnostics.

HVAC sensors are dominated by temperature sensors, which 
in wood stoves are usually Type K thermocouples that 
typically cost a dollar or two.

Is this trend likely to come to wood stoves? Yes — and in multiple practical ways:

The increased use of sensors in stoves is likely for many reasons, not least of which is that they should make it easier to pass new certification tests in the US and Europe. Automation directly address the IDC’s challenge of consistent, repeatable combustion across varied loads and user behavior. That could make automation an attractive technical route to meet performance targets reliably. However, many manufacturer don't have experience with sensors and will likely want to optimize passive design, secondary combustion, or catalytic systems rather than add electronics.

The biggest hurdle in the short term is that government regulators in the US and European countries often do not have the expertise, resources or clout to overcome resistance by industry to changes leading to improved test methods and stricter emission limits. The US currently has an industry friendly, anti-regulatory administration, which could mean individual states get more involved.

Politics aside, the sensor boom is applicable in wood stoves in obvious ways:

• Combustion efficiency: O2, CO, and temperature sensors can enable feedback-controlled air supplies to keep burn in the optimal stoichiometric window, increasing heat output and reducing fuel use.
• Emissions reduction: particulate sensors (optical) and CO monitors can detect smoldering or incomplete combustion and trigger corrective measures (adjust draft or alert the user), reducing smoke and creosote formation.
• Safety: CO sensors and high-temp cutoffs can warn of dangerous conditions or auto-shutdown linked to ventilation failure.
• Draft and airflow control: pressure or differential-pressure sensors across the stove and flue help manage draft for steadier burns.
• Predictive maintenance: temperature profiles, and smoke signatures can indicate gasket wear, or creosote build-up.
• Remote monitoring and automation: smartphone alerts, remote adjustments to air dampers or blower speeds, and usage logging for fuel optimization.
  
  

  

  In the US, the Department of Energy is
  also supporting important automated 
  stove research at Nordica McCarthy's
  lab at Oregon State University

Practical considerations and challenges for wood stoves

Wood stoves present unique challenges because they use a solid fuel with very diverse characters, unlike electricity liquid fuels. In addition:

• Harsh environment: soot, ash, high temperatures and corrosive gases require rugged sensors and protective housings.
• Sensor placement: measuring combustion gases accurately often needs sampling ports or heated lines to the sensor; fouling is a risk.
• Power and connectivity: many stoves are off-grid or in remote cabins; low-power sensors and local edge logic are important. The ability of the stove to work without electricity/sensors is important.
• Cost vs. value: retrofit kits must be affordable and simple; OEM integration at manufacture yields better reliability.
• Certification and safety/regulatory acceptance: devices that influence combustion or safety need testing and standards compliance.
• User behavior: alerts are useful only if users understand and act on them; automation helps and users are learning from all the other sensor interactions in their daily lives.

Jotul says this stove "continually
monitors  temperature  and
automatically  adjusts  air supply  to
optimize combustion — giving cleaner,  more
efficient burning  and reduced emissions."

How this could be deployed

• OEM integration: manufacturers build sensors and control loops into new stoves (best performance and reliability).
• Retrofit modules: compact sensor packs (temp, CO, O2, particulate) with a local controller and optional wireless gateway for older stoves.
• Service-focused models: subscription diagnostics for stoves used in rentals, remote cabins, or commercial premises – or in any stove where the user wants greater peace of mind.
• Simple consumer features: auto-damper control, burn-stage alerts, and CO alarms tied to phone notifications.

Bottom line: Falling sensor costs, smarter edge processing and connectivity are driving a widespread sensor adoption in vehicles and home equipment — and that momentum should continue. Wood stoves are a natural candidate for the next wave of sensor-driven improvements: safer, cleaner, and more efficient burning is technically feasible today, but practical rollout requires rugged sensors, thoughtful placement, simple user interfaces, and standards-compliant designs.

Innovation in stove technology will also be driven by public health concerns. If wood stoves continue to be popular or become more so due to rising heating fuels - electricity, gas and oil - there will likely be more pressure on governments to do a better job at certifying new stoves. However, global warming is making winters warmer, reducing heating bills, which typically reduces the use of wood stoves, which in turn may ease pressure on air regulators.

Blue Angel ecolabel requires wood stoves with automated air controls

Blue Angel, the German government equivalent of the US Energy Star label, approved a new eco-label for wood stoves that includes stoves with automated air control, “separating technologies” such as electrostatic precipitators and the ability to meet strict emission standards.

The Blue Angel label is also part of a trend that is exploring and adopting test procedures that more closely resembles how stoves are used in homes.  The label emerged in part from lessons learned by the BeReal initiative that involved extensive round-robin testing in multiple European countries. The Clean Heat initiative is promoting the label to help towns and cities to reduce air pollution.

Marius Wohler of BeReal presents
findings at Brookhaven National Lab
 in 2016

The label gives a boost to efforts by the Alliance for Green Heat which has worked with American state and federal agencies and American stove manufacturers to develop automated stove technology and bring them to the US market.

German Federal Environment Minister Svenja Schulze said in a press statement that "The Blue Angel standard for stoves for wood is a real step forward. The authorities can now take more effective action against particulate matter pollution, for example by only allowing the operation of stoves bearing the eco-label.”

Blue Angel says that cities and municipalities are introducing regional bans on conventional stoves (ban on the use of these stoves and ban on installing these devices in new housing developments) but there would be exceptions for those appliances holding the Blue Angel label. The city of Berlin has expressed interest in using the ecolabel.

Maria Krautzberger, President of the Federal Environment Agency said “With the Blue Angel requirements that have now been decided upon, we are showing that it is possible to go even further [to make wood stoves clean]. This boosts innovation in the industry, gives guidance to consumers and is good for our air".

SBI won an award for their automated
stove design and will be launching a series
of automated stoves in North America

The label is voluntary for manufacturers, as a number of other European eco-labels, but this one is stricter than others. Several European countries have developed eco-labels for wood stoves with varying degrees of success. The US Energy Star program has never covered wood stoves and US stove industry blocked an initiative by Washington State to explore a state-led label. The Alliance for Green Heat has been an advocate for ecolabels and urges stakeholders in the US to revisit the idea.

It is not yet known how many stoves will qualify for the label over the coming months and years, and how well they will work in the field. Automated stoves gained some visibility in the United States through the Wood Stove Design Challenge and subsequently the Department of Energy provided $3 million in funding for automated stove R&D in 2019 and are now offering an additional $5 million in 2020.

Electrostatic precipitators (ESPs) have long been used in commercial wood burning applications, and their use in residential applications has grown rapidly in Europe. In the US, an initiative in Alaska is using ESPs, and is hoping a review by the EPA will determine that change out funding can be used on a wider scale to install ESPs on wood stoves.  As prices come down under $2,000 the cost of adding an ESP may result in far more PM reductions than replacing an old stove.

This ESP made by Swiss
company Oekosolve was
also showcased by AGH
in Wash. DC in 2018.

Excerpts of the details of the Blue Angel label are reproduced below. The full criteria can be found here.

Excerpts

The environmental label may be awarded to stoves that use the fuel … in an efficient manner and have significantly lower pollutant emissions. In addition to the statutory regulations for the type testing process [lab testing of a sample stove] for the stoves, the special requirements stipulated by the Blue Angel mean that stoves have to comply with significantly lower particulate and CO limit values and this must also be verified during the ignition [start-up] phase that involves a particularly high level of emissions. In the case of organic gaseous carbon (OGC) and nitrogen oxides (NOx), emissions of these substances must already be below the limits defined in the EU Ecodesign requirements that will be generally applicable from January 2022.

When purchasing a new innovative stove, the environmental label will thus act as a decision- making aid for the reduction of air pollutants. It is a voluntary label that is designed to motivate manufacturers to develop efficient and low- emission heating appliances. The label will allow manufacturers to highlight the environmental benefits offered by their heating appliance in a simple way.

Therefore, the following benefits for the environment and health are stated in the explanatory box:

3.1 Emission requirements

Stoves, where relevant in combination with an integrated or downstream particle separator, must comply with the maximum limits stated in Table 1, Column 3 for the particle content, carbon monoxide (CO), organic gaseous carbon (OGC) and nitrogen oxides (NOx).

The particle count concentration must be determined (see Appendix C for the measurement method). In addition, the limit for the particle count concentration stated in Table 1, Column 3 must also be observed from 01/01/2022.

The requirements can be complied with in two ways:

1. a) Testing the overall system

The requirements will have been fulfilled if the mean values from the individual measurements described in Appendix B that were carried out on the tested stove, including all of the intended fixtures and attachments, do not exceed the relevant limits specified in Table 1, Column 3.

Spare parts are those parts which, typically, may develop a fault within the scope of the ordinary use of a product. Whereas those parts which normally exceed the life of the product are not to be considered as spare parts.

2. b) In combination with an efficient particle separator

§ The requirements will have been fulfilled if the mean values from the individual measurements described in Appendix B that were carried out on the stove do not exceed the relevant limits specified in Table 1, Column 4 and the stove is sold and installed together with a particle separator. For particle separators, a minimum separating efficiency of 75% of the particle mass and (from 01/01/2022) 90% of the particle count must be verified. The limit value in Table 1, Column 3 must be complied with reliably when taking into account the separating efficiency.

§ If a particle separator for which this minimum separating efficiency has been verified is already integrated into a chimney, the manufacturer can also sell the stove without the separator. The fact that the stove must be installed together with the associated particle separator that is integrated into the chimney must be indicated during the sale of the product and also in the installation instructions. The particle separator integrated into the chimney must already have been named and tested when submitting the application for the stove.

The measurement of the flue gas temperature, the flue gas sampling process and the measurement of the static pressure for the stove must be completed in a measurement circuit according to DIN EN 16510-1:2018-01 (D), Section A.2.3 as well as Diagrams 13 and 14 of this standard.

The measurement uncertainty stated in the test method is neither added nor subtracted.

3.11 Future revision of the environmental label

Furthermore, the revision will examine whether the applicant can offer a 5-year guarantee for the secondary reduction technology if it is sold in combination with the stove. 

To determine the particle count emissions from stoves, it has only been possible up to now to evaluate individual test results using the methods described in Appendix C. Round robin tests that could be used as the basis for defining a limit for the particle count emissions from the stove have not been available. 

Nevertheless, the measurement of the particle count in accordance with the new methods is being introduced as an obligatory requirement. Due to the unavailability of round robin tests, it is necessary to allow a transition period for the introduction of the particle count limit. Compliance with the particle count limit will be obligatory for the award of the Blue Angel from 01/01/2022. 

3.4 Air regulation

To ensure that the user has as little influence over the emissions as possible, it is not permitted for the air supply to be manually adjustable during intended operation. This is usually achieved through the automatic regulation of the air supply.

3.5 Combustion monitor

A display must be provided for the user to indicate any deviation from the optimal operating state and to request that the user stokes the fire with wood.

3.8.1 Repairability and provision of spare parts

The stove must be designed so that it can be repaired by replacing individual parts that are no longer working. The applicant undertakes to guarantee the provision of spare parts for the repair of the appliances for at least 10 years following the termination of production.

The product documentation must include information about the repairability and the guaranteed supply of spare parts.

3.8.2 Recyclable design

In terms of the recyclable design of those appliances issued with the environmental label, the following is valid:

· The appliances must be designed in such a way that they can be dismantled and separated into recyclable materials by specialist companies using standard tools or that this process is simplified by intelligently designed connections.

· The appliances must be designed so that it is possible to separate metals into single materials and, where possible, recycle them separately.

3.10.3 Quick user guide

· In addition, another guide covering a maximum of two pages must be provided that includes the most important instructions for the fuel to be used (size of the pieces, max. water content, quantity) for the ignition process, controlling the air flow, stoking the fire and cleaning/maintenance in a clearly visible and easy to understand form. This quick user guide must be permanently legible and abrasion-resistant and must not suffer from discolouration during normal use.

· The instructions must include easy to understand illustrations

5. Use of the Environmental Label

The use of the Environmental Label by the applicant is governed by a contract on the use of the Environmental Label concluded with RAL gGmbH.

Contracts on the Use of the Environmental Label are concluded to fix the terms for the certification of products under Paragraph 2. Such contracts shall run until December 31, 2023. They shall be extended by periods of one year each, unless terminated in writing by March 31, 2023 or March 31 of the respective year of extension.

Related stories

Alaska building list of cleaner, properly certified wood and pellet stoves (Oct. 2020)

The US needs an eco label for wood and pellet heaters (Dec. 2018)

Danish stove industry looks to compete, grow in America

This award winning Aduro stove accepts
wood and/or pellets and can switch
between them automatically.

Companies must navigate and anticipate shifting regulations on multiple continents

The Danish stove industry is known for sleek, vertical, expensive stoves. There is a joke that they are made to look like high end furniture that happens to hold a fire. But amidst this new wave of modern design is an industry that embraces innovation, competes worldwide to heat homes and has many budget line models.  

Danish stove makers tend to be skeptical of catalysts, very comfortable testing with cordwood, committed to quality and adaptable to the preferences and requirements of different countries. Danish stove manufacturers also have their own EPA-approved test lab at the Danish Technological Institute, one of three European labs that are now approved for EPA certification testing.    

John Ackerly, AGH President
with Jes Sig Andersen and Anne-
Mette Frey of DTI. AGH photo

One of the most exciting new Danish stoves burns both wood and pellets. It can run off pellets, just like an ordinary pellet stove, but then you can load the firebox with cordwood, drastically reducing start-up emissions. When the wood fire dies down, it will automatically revert to pellets. The stove is made by Aduro, a major European manufacturer that has not yet entered the US market but will likely do so.

Danes do not appear as intimidated by sensors and smart control systems as their American counterparts. They may appear on the market quietly, with little fanfare, and possibly without the consumer even knowing what’s under the hood. Since they require very little power, they may just have a couple batteries and don’t have to be plugged into an outlet. The trick is to get those sensors past the 2020 emissions standards with or without using a single burn rate test.

Aarhus – the stove capitol of Europe

No city in Europe is surrounded by as many stove manufacturers as Aarhus, the second largest city in Denmark. It is located on the mainland, just a few hours north of the German border. Brands well-known to North Americans include Hwam, Rais, Morsø

Aarhus is on the Jutland Peninsula, the 
Danish mainland, an academic center 
and Denmark's the second largest city.

 and Scan, but the city is also home to others that are as big or much bigger, including Aduro, Heta and Termatech. All these brands are present in many if not all European countries.  

Aarhus is centrally located with wind turbines and biomass district heating plants dotting the surrounding countryside. The hundreds of small biomass district heating plants pipe hot water underground to virtually all homes in cities, towns and suburbs. The extensive network of district heating is one of the main reasons that Danish stoves tend to be small.  Most homes already have affordable and renewable heat. Rural homes that are not on the district heating grid usually have pellet boilers, made by one of the many Danish pellet boilers companies. Danes also have innovative boilers for farms that use hay bales, another novel technology that could have a market on America’s farms.

EPA’s 2020 emission standards and foreign stoves

Danes have always tested their stoves with cordwood (only Norwegians test with cribs). The ASTM cordwood standard that allows up to 2.5 grams an hour appears to be achievable, according to Danish manufacturers. EPA certification has always been considered the gold standard in Europe and is universally accepted as the hardest test a European stove can pass.  

Jes Sig Andersen of DTI lab in Aarhus,
 left, with a technician at the Rais lab. AGH photo

The 2020 standards make it even harder for manufacturers. Danish stoves “can’t be tweaked, they need to be redesigned,” says Jes Sig Andersen, a senior specialist at the stove test lab at the Danish Technological Institute (DTI). The entire system that delivers primary and secondary air has to be reengineered and optimized to ensure maximum combustion of particulates through primary oxidation, secondary pyrolysis and often tertiary combustion. Getting that just right is a challenge even for seasoned combustion engineers, who have spent their professional lives designing stoves for the laxer protocols required in Europe.  

At a seminar hosted by DTI on stove and boiler testing, AGH President John Ackerly presented a powerpoint (PDF) on the current state of EPA regulations, potential changes, and other cordwood test methods that are in development.

Danish attitudes toward wood heating

The Danish landscape is dotted with
small biomass district heating systems,
which often use chips or hay bales.

There is an ambivalence toward wood heating in Denmark that is similar in many respects to attitudes in the US and in many European countries. Wood heating is often viewed as too polluting, a result of too many old stoves and poorly operated new ones. Pellet stoves comprise an even smaller part of the market here but pellet boilers are far more commonplace. In the capital city of Copenhagen, the mayor, like the mayor of London, is cracking down on cordwood stoves and plans to ban their future installation in part of the city. One of the largest crackdowns in Europe is in the Po River valley in Northern Italy where regular inversions trap wintertime pollution.  

The Danish government has had national change out or scrapping programs that provide a US $300 grant to simply remove an old stove, or replace it with a newer certified stove (it does not have to carry the Nordic Swan eco-label).

Vertical, clean lines and small fireboxes
dominate the Danish domestic market.

Because Denmark has a culture that looks down on overnight burns, extremely few models produced here have large enough fireboxes to do that. Some local jurisdictions banned overnight burning as it is almost synonymous with smoldering. Danes tend to want smaller stoves anyway, not as a primary or even a secondary heater as much as for the ambience. Younger Danes are more likely to install a gas stove or just a heat pump for space heating.

Danish automated stoves

The Hwam smart controller allows
the user to load and leave, and uses
sensors to adjust the air.

Aarhus stove maker Hwam was one of the first to design a fully automated stove, with an Intelligent Heat System (IHS) which competed in the first Wood Stove Design Challenge in 2013 in Washington DC. That stove helped revolutionize the concept of what a wood stove can be, and how it can be assured of operating cleanly in the hands of consumers.  Other Danish manufacturers have also used sensors and controllers that will be coming out in future models. The Hwan IHS has held its own in the marketplace, but price conscious consumers still prefer more basic, cheaper stoves.

The Aduro hybrid that burns both pellets and cordwood uses automation by necessity, so that it knows when the operator has loaded cordwood and when the stove needs to switch back to pellets.  

Henrik Norgaard, CEO of Rais
explaining their upcoming automated
stove that gives consumers confidence
in clean during technology. AGH photo

Rais has an automated stove in development that pairs Maxitrol controls with smart phone connectivity to allow users to monitor and adjust it. Basic automation can also prevent overfiring on one extreme and extended smoldering on the other, a key safety features that may catch on in the marketplace. 

A German company, Thermoelect, is marketing their automated stove in Denmark, looking for buyers who desire heat, domestic hot water and reliable electricity from a very clean burning system. That stove won first place at the 2018 Wood Stove Design Challenge in Washington DC based on its efficiency, emissions, electric output and innovative design. 

A key question is whether local and national governments will support the advancement of automated stove technologies that help stoves operate better in the hands of consumers. Automation should be

Horst Erichson holds the trophy his
automated stove won at the 2018 Wood
Stove Design Challenge. Rene Bindig
from the German Biomass Research Centre
consulted on the firebox design. AGH photo

able to help stoves pass stricter emission standards such as the EPA’s 2020 standards. Otherwise, there may not be sufficient incentives for stove manufacturers to build stoves that do much more than operate well in the test lab.  

European Union 2022 Emission Directives result in weaker emission limits in northern Europe

A weakness of European wide emission standards for wood stoves is that they are the product of a

negotiation between countries with stricter standards, and countries that have no standards at all.  One of the key purposes of the Union is to harmonize standards so that goods can flow freely between all EU countries, which means that countries cannot maintain stricter standards than others. For countries like Denmark and Germany, this can result in having to weaken emission standards. The 2020 EU Eco-Design Regulation calls for a maximum of 40 mg/cubic meter for wood stoves and 20 for pellet stoves. Denmark already requires a max of 30 and most stoves are in the 10 – 20 range. Denmark may be able to negotiate keeping their stricter standards which would also result in keeping some stoves made in other countries out of their market. But the more powerful European stove industry associations may block a country’s attempt to keep stronger standards so that they can build stoves to the laxer standards. 

One reason that European stove testing protocols are laxer is that they typically only have to test at a nominal heat output rate. They do not have to test at their lowest air setting or heat output rate. They also allow fueling to be based on manufacturers’ instructions and do not require the stoves to be filled with nearly as large loads as EPA protocols. However, there are national variations and the Norwegian national protocols required testing at 4 burn rates and with crib wood.

beReal and IDC testing protocols

Round robin testing of the same stove in different labs and
settings shows emissions are often double or triple in the real
world compared to lab testing. 

Danish stoves for export to the US are much more likely to be tested with the ASTM cordwood method, which should make them somewhat cleaner in the hands of consumers. But using cordwood and including start-up emissions is just the beginning of innovation needed in test protocols. Stricter PM limits only result in cleaner stoves if there is a level of integrity in the test method that does not exist in Europe or North America. On both continents, industry has played a big role in writing the test methods and labs in both continents have a financial stake in making sure their clients pass the test.  

The need for more real-life test methods is just as obvious to Europeans as it has become for Americans. Even before NESCAUM began developing Integrating Duty Cycle test methods, European began beReal, a very similar process to understand the weaknesses of existing lab testing and move towards a method that would result in stoves being designed for consumers, not for test labs.

An early overview of the IDC protocol
under development by NESCAUM.  The
protocol had early input from HPBA but
 they have since dropped out of the process.

A ground-breaking 2018 report, “Advanced Test Methods for Firewood Stoves” by Christoph Schmidl and Gabriel Reichert, concluded that “Real-life oriented test concepts (e.g. beReal) are capable to reflect the real-life performance of the appliances better compared to existing EN standards. An implementation of a real-life oriented test protocol as a quality label or standard should be considered as an instrument to push technological development towards optimized real-life operation and to enable a better differentiation of good and poor products for the end customer.” 

Marius Wohler, manager of the beReal
initiative speaking at the 2016 Pellet
Stove Design Challenge at Brookhaven
Nartional Lab. AGH photo

The authors suggest that establishing a voluntary test method that could be used as the basis for an eco-label could justify the costs of developing the method and provide an incentive for stove manufacturers to test to it. Wood stove eco-labels, while common in Europe, are not supported by the wood stove industry in the US, which has never had any eco-label for stoves.

The adoption of more realistic and effective test methods based on the European beReal initiative or the American Integrated Duty Cycle approach will face headwinds. Regulators may not have the time, expertise or motivation to engage in a major test method shift, and industry may resist leaving charted waters that they know how to navigate for seas that may pose tougher challenges. But both continents have persistent stakeholders and face air quality and renewable energy targets that require technologies to operate cleaner in the field, not just the lab.

Compliance audit testing or "market surveillance"

Regulators on both continents also realizing the need for compliance audits, called “market surveillance” in European parlance. Without effective oversight of test lab results, a culture of artful, possibly legal, manipulation of test protocols can grow in labs.  Once the culture exists in one lab, other labs need to follow to keep their clients from going to labs who can help stoves pass more easily.  The Alliance for Green Heat wrote about this danger in 2015 in the wake of the Volkswagen testing scandal. That scandal involved a emission testing defeat device, but it also uncovered an old boys network that stayed quiet about a culture in labs that is driven more by client pressure and expectations than government-approved test protocols.

Under the U.S. Clean Air Act, the EPA has authority to conduct compliance audit testing of stoves

A page from a 2017 Belgian list
of stoves whose sale was banned
after audit testing was performed.

and revoke a certification if the particulate matter exceeds the original lab test by 50% or more.  That provision is under litigation by HPBA and other stakeholders agree that if the PM is below 1 gram per hour, 50% is too strict given the variability of solid fuel testing.  European countries have similar compliance laws, and Belgium has begun to conduct audit testing and cracking down on stoves that it believes may have exaggerated test numbers.  They issued a seven-page document, "List of devices tested in the laboratory" (pdf) that banned the sale of nine mostly Spanish Panadero stoves in Belgium based on discrepancies in PM or CO between the certification lab and the audit lab.  

Panadero is a family run, mass market value stove manufacturer that like many other companies

The Panadero website shows the eco-
labels that some of its stoves carry.

claims to have met the 2022 standards for all its stove in 2018.  In addition, some Panadero stoves carry the French Flamme Vert and British HETAS and other eco-labels.  They apparently do not qualify for the Nordic Swan or Blue Angel.  Most of the stoves found to have a large PM and/or CO variation in 2017 Belgian audit compliance tests appear to be out of production as of 2019. One that is still in production, the Luis, does not claim to meet any European eco-labels.

Can Danish stoves gain traction in the US market?

Vertical, stylish European stoves led by Danish companies have been slow to catch on in the US market. But the entry of Danish value stove makers could change that. They already make more horizontal style stoves with larger fireboxes for the British and other markets. Danes could have a real advantage with sensor-equipped stoves that have sensors that take some or all of the “idiot factor” away from the operator. If tests can better show the value of these stoves, then it will be up to federal, state and local jurisdictions to find ways to help pave the way for them to proliferate. The recent funding opportunity from the US DOE is clearly looking for R&D in automation, and that may be a tipping point for automated stoves. Danish companies are not eligible for that, but they are well-positioned to benefit from any trend in that direction. 

European stoves may also be a beneficiary if the trade war between the US and China escalates.  

Many Danish export stoves are
more horizontal and have larger fireboxes
for Eastern European and British markets

Tariffs on steel and parts such as fans could impact American manufacturers far more than European ones, which could benefit Italian pellet stove manufacturers, for example.  

Regardless of their share of the US market, Danish stoves represent an enduring aesthetic. They are also expanding into Eastern Europe, where some of them are manufactured, and where cleaner, more efficient stoves are needed far more than North America and Western Europe. It is difficult to know how regulations, innovation and energy demands will impact wood stoves, but Danish stove makers are likely to be on the forefront of those changes.

Related stories

Alaska building list of cleaner, properly certified wood and pellet stoves (Oct. 2020)

The US needs an eco label for wood and pellet heaters (Dec. 2018)

Automated Wood Stoves Entering the Marketplace

Updated: Nov. 2020: There are at least a half dozen stoves on the market that are fully automated or have some automated features that are gaining traction.  Many of these features help the stove burn cleaner and are aiming at a demographic looking for easier operation.

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 sometimes 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.

There is only one fully automated stoves on the US market and several more that will be released in 2021.   MF Fire, a Baltimore-based company makes the fully automated Catalyst.  It uses electronic sensors to monitor combustion and adjust air flow as needed.  SBI has an automated stove in the final R&D stage and Buck stove is participating in an automated stove project, both of which are funded by the bioenergy office of the Department of Energy.

MF Fire, a small Maryland
company is trying to disrupt
traditional stove technology.

The automation in the Catalyst is a great option for consumers who want to minimize smoke from their stoves and enjoy the ease of automation.  You can more easily leave for the day or go to sleep at night knowing that your stove won't be smoldering away, which is one of the leading causes of excessive pollution from both old and new wood stoves.

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. 

In 2013, 2014 and 2018, 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.

1. The bi-metal coil. One of the oldest forms of automation of steel wood stoves is the bi-metal coil which has been used on scores of stove models and is now mostly just used by a few catalytic stove makers, principally Blaze King and Vermont Castings.  A bi-metal coil is simply a thermostat run by a metal coil that can close a damper down when it's really hot, and open it up when it's cooler. The stove’s air inlet can still be operated manually, but the bimetal coil will adjust the air inlet further. They tend to not work nearly as well on non-cat stoves, because the temperatures in a non-cat firebox can be more unpredictable, and if the coil shuts down the air, or opens it too much, the stove would operate poorly, which adds far too much uncertainty in passing the EPA emissions certification test. A new, more sophisticated version of this technology is the VcV valve developed by a Australian company and Ben Myren.

The rotating trigger mechanism in the
Smartstove Collection by Englander
reduces air flow once the stove is hot.

2. Better start-up: Several companies have features that help start-up: the Quadrafire "Automatic Combustion Control" and the Travis "Green Start."  They all use different automated approaches to starting the fire quicker and with fewer emissions.  After the start-up period, the stove operates like any other.

Quadrafire's Explorer 2 Start-Up air
control helps give the stove more
air in the first 25 minutes.

Another recent arrival on the market is Quadrafire’s Explorer II, which provides a similar automated start-up.  The website says “Automatic Combustion Control-provides the fire with air when it is most needed-leading to longer burns.”  A marketing video says the operation is so easy that all you have to do is “load the wood, light the fire and walk away.” According to the installation manual, ACC is basically a timer which the operator must manually initiate with a control mechanism.  Essentially, it opens the front air channel which allows air to enter for 25 minutes before closing.  Once the front air channel is closed, manual controls are used to deliver preheated air to the top of the firebox to burn the rest of the unburned gases in the remaining three combustion zones.

The slider on the Cape Cod
adjusts the rate of burns.

Travis industries Hybrid-Fire technology™ developed an automated “Greenstart” which shoots 1,400 degree air into the firebox for 15 minutes to start your fire, or when you reload.  The Greenstart can significantly reduce start-up emissions, and emissions during reloading on a low temperature bed of coals, by jumpstarting the start-up process and heating the wood up faster than it would with newspaper.  After the first 15 minutes, the stove has no automated features, but some of the Travis stoves that use catalysts are among the cleanest in the industry.  The Travis Cape Cod stove won second prize in the Wood Stove Decathlon.

3. 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.

Fully automated stove on the European market

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. 

2. There are numerous versions of the Rikatronic wood heater system. The Fox II stove features manual and automatic control settings.  In manual mode the air distribution can be controlled in each combustion phase-even in the event of a power outage.  Automation in Rikatronic technology works with a microprocessor-controlled motor and flame temperature sensor which operates the RLS air distribution system.  Airflow in each of the 5 combustion zones is effectively adjusted for efficient burn.  A red light indicates the optimal time to reload the stove.  You can set the room temperature you want and once the required room temperature is reached, you can activate the eco mode by pressing the Rikatronic³ button.  This causes the air supply to be optimally controlled to maintain the fire for as long as possible, without smoldering, and to leave behind as little ash as possible.  Power consumption is 2 – 4 watts.