Temperature and oxygen sensors make cars, furnaces, boilers and scores of other products operate as and maximizing efficiency. So, why hasn’t any North American
manufacturer integrated them into wood stoves yet? Dan McFarland, a stove inventor asked many people in the stove
industry and came up with this list of the 9 most common reasons sensors are
not used:
cleanly and efficiently as possible by regulating combustion, reducing particulate emissions
1. They have put controls on "wood" stoves.
They are
called pellet stoves. 2. They don't need to.
The marketplace is not demanding it, mostly because people don't know the technology is available.
3. It's a new technology.
Wood stove manufacturers are dreadfully slow with adopting new technologies.
4. They don't use wood stoves themselves.
The vast majority of upper management in stove companies don't heat with wood, so they don't understand the benefit of automation.
5. They're not being forced to.
Why add complexity to a product that sells well and requires little support?
6. It's too expensive.
Any new technology starts out in low volumes and is expensive. Stove companies are very cost conscious.
7. They can do the same thing with a bi-metallic spring.
Bi-metallic springs do provide some measure of control.
8. It might require electricity.
There is a perception in the industry that people who heat with wood don't want to plug in their stove.
9. They have other projects to work on, like pellet & gas stoves.
The gas stoves are by far the products that ship in the highest volume, and pellet stoves are growing in volume. Wood stove shipments are flat, so they spend their resources on these other areas. Some manufacturers go years without making any significant changes to their wood stove line.
These 9 reasons are reproduced with permission from and you can can read more about's Dan's automated prototype here. Here are 3 more of our own, for good measure:
10. No incentives from the government.
Unlike in Europe, in America there are no incentives for cleaner and more efficient wood stoves. There is no Energy Star rating or green label equivalent to reward customers for buying, and manufacturers for producing, the cleanest and most efficient products.
11. Not enough efficiency data.
There is little data about actual efficiencies in the
field over the course of a day of heating. Could 70% in the lab be 55% if averaged over the course of a fire?10. No incentives from the government.
Unlike in Europe, in America there are no incentives for cleaner and more efficient wood stoves. There is no Energy Star rating or green label equivalent to reward customers for buying, and manufacturers for producing, the cleanest and most efficient products.
11. Not enough efficiency data.
12. Fuel is still relatively cheap.
Fossil fuels are still relatively cheap and plentiful in the United States, and so is firewood.
Postscript: Since we published this blog in 2013 there has been some minor progress toward including low cost sensors in stoves. MF Fire, a new company, released an automated stove controlled by sensors and SBI is developing sensor technology that hopefully will be in certified stoves in 2019.
What do you think of the list? Are we forgetting any reasons why U.S. manufacturers aren't incorporating sensor technology in wood stoves? Leave your thoughts in the comments section below. You can also check out our previous coverage of wood stoves and oxygen sensors here.
I think this is a rather simplistic list. The presumption that electronic automation would be an unalloyed good thing if only the industry gave a damn ignores the technical hurdles, none of which are addressed here, and many of the reasons listed don't survive even casual scrutiny.
ReplyDeleteThe big problem is that cordwood is an extremely variable fuel source. Such technology is easy to implement in a pellet stove because pellets are consistent and predictable, so the algorithm for how the stove should adjust itself according to sensor input is relatively simple. Cordwood may be wet or dry, large pieces or small, one species or another, and it can't be continuously fed from a hopper. As a result the algorithms needed to manage a cordwood fire automatically are a lot more complicated and error-prone, and substantially less useful. The cost/benefit balance is not equivalent.
"The big problem is that cordwood is an extremely variable fuel source" - I think this is EXACTLY WHY u need a automatic self adjusting automation.
DeleteFor a consistent and predictable fuel u adjust the setting once and will always burn the same way.
With a variable fuel source as wood is, u need to adjust the settings of the boiler for every different batch of wood u load. As for the part that such a system should be more complicated don't know if is true. The adjusting algorithm should be the same (since the input value are the same) only repeated more frequent so the algorithm shoul be the same but repeated more frequent no?
Jon, thanks for leaving those comments. Yes, it is a rather offhand list. The technical hurdles have been worked out relatively well in many residential wood-fired boilers currently on the market and I'm sure we'll see many advancements and improvements in coming years. But I would think that its precisely because wood is so variable that automation could be so beneficial. I understand how passive or human controlled pellet systems can work well, because of their consistency, but how can passive or human controlled wood systems achieve better results than the automation that exists in some wood boilers with oxygen sensors, etc?
ReplyDeleteI agree with Jon, not a very convincing list. I think the homeowners' desire for a woodstove that does not require electricity cannot be underestimated. The consumer is rarely trying to decide between a pellet stove and a woodstove.
ReplyDeleteI would also suggest that the added cost of lambda sensors and temperature probes needs to include the things that they control and the added cost is significant. Highly sophisticated woodburning appliances with lambda controlled primary and secondary air shutters and modulating combustion fan already exist, they are boilers and they cost upwards of $10k. The difference in cost between the non-lambda and lambda boilers in our lineup is about $1500.00 at retail.
I love this contest and am very much looking forward to seeing the entries in person, but I think pursuing an electric/electronic woodstove is barking up the wrong tree.
Errr, What if we turned the question around? Perhaps we could list 9 ways manufacturers could benefit by incorporating oxygen sensors in wood stoves.
ReplyDelete