Are Dampers Legal?

[NorMi]

And when you increase the range of operation so it's wide enough to work in the real world, you can no longer get your EPA certification because the stove turns down too low for the test setup.

This should never be possible on a mass air flow compensated stove if one were to be designed - the idea is to make the user settings, insofar as there are any, correspond at all times to true, known mass air flow rates. Draft compensation integration into the intake throttle settings would work with stove differential pressure feedback as one of several inputs that would deliver a single target airflow solution, so the EPA test rig draft and the 40' chimney in 80 mph winds should always achieve the same mass air flow rate and chamber residence times in all realistic conditions, perfectly matching the manufacturer's designed airflow range(s) for any given install (so long as it's not experiencing problems like flow reversion/backdraft/etc).

This would require lower and more precise real-time achievable minimum open intake area on the stove, but would only be able to be activated automatically in practice when the pressure compensation allows the throttle to drop that low. It would be easiest to accomplish repeatably over the long term with electronic control which would be my preference, but a combination of mechanical pressure and thermal compensators carefully calibrated for mass air flow should be theoretically realistic as well - after all it's about as complicated as carburetors or automatic chokes, which can work pretty darn well. Separate controls for primary and secondary air pathways would not be desirable, that would be like a car with two gas pedals and two drivers.

The main problem is it costs far more to develop and manufacture something like that than it does to print a line calling out a narrow range of allowable install parameters in the manual. If you are min-maxing for profit, making something that passes the test and serves the majority audience will get the largest and fastest returns... and get more dampers installed in the field. 🤷‍♂️

 

[ABMax24]

This should never be possible on a mass air flow compensated stove if one were to be designed - the idea is to make the user settings, insofar as there are any, correspond at all times to true, known mass air flow rates. Draft compensation integration into the intake throttle settings would work with stove differential pressure feedback as one of several inputs that would deliver a single target airflow solution, so the EPA test rig draft and the 40' chimney in 80 mph winds should always achieve the same mass air flow rate and chamber residence times in all realistic conditions, perfectly matching the manufacturer's designed airflow range(s) for any given install (so long as it's not experiencing problems like flow reversion/backdraft/etc).

This would require lower and more precise real-time achievable minimum open intake area on the stove, but would only be able to be activated automatically in practice when the pressure compensation allows the throttle to drop that low. It would be easiest to accomplish repeatably over the long term with electronic control which would be my preference, but a combination of mechanical pressure and thermal compensators carefully calibrated for mass air flow should be theoretically realistic as well - after all it's about as complicated as carburetors or automatic chokes, which can work pretty darn well. Separate controls for primary and secondary air pathways would not be desirable, that would be like a car with two gas pedals and two drivers.

The main problem is it costs far more to develop and manufacture something like that than it does to print a line calling out a narrow range of allowable install parameters in the manual. If you are min-maxing for profit, making something that passes the test and serves the majority audience will get the largest and fastest returns... and get more dampers installed in the field. 🤷‍♂️

I agree with you, although I've tried pointing it out in the past and have been met with a lot of opposition because people don't want "complex computers" on their simple stoves.

I'd go out and build such a stove myself if it wasn't so expensive to get the stove certified for emissions or a UL listing.

The reality is the operator is the primary factor in poorly performing stoves (which includes the operator burning wet wood), followed by a non-typical install. Automation can remove the operator (mostly) and compensate for a less than ideal install, but it still doesn't help if wet wood is used.

The reality is the "final EPA 2020 emissions standard" can't be final, there has to be improvement, for now the burning of coal, diesel and gasoline vehicles are still taking much of the blame for poor air quality. As EVs become more popular and coal is continued to be phased out wood heat will again attract attention for its contribution to lowered air quality. There will need to be another improved step for wood stoves emissions to allow wood heat to continue in the coming decades. I simply don't see how this can improve without automation of the controls.

 

[Dieselhead]

At the beginning of my burn my stove will at least double the Mfg’s draft requirement. To keep it in check I use a damper. Once the burn settles in I open it fully and the draft is (mostly) in spec once the stack cools down.
I run a manometer at all times.

 

[begreen]

As much as regulating agencies love to shoehorn things into tightly designed rules, this does not work for woodstoves. Take the 2015 NSPS for instance. It makes no account for emissions on anything outside of the 15 ft single flue length in the lab. What are emissions in a modern stove when strong draft overwhelms the stove's ability to burn up all the flue gases? It's like testing brakes at 30mph and ignoring what happens at 60. There is no way rules can cover what happens with varying species and moisture wood, let alone the variables of operation, outdoor temps, etc. Some stove makers wisely account for these variables in the manuals and recommend a stovepipe damper in strong draft situation.. Some unfortunately are written more from a CYA standpoint that does not help the homeowner at all.

 

[Highbeam]

Nothing to add, just thinking about this thread as I swing the damper 3/4 closed in my very clean, per epa gph test, noncat stove since it’s 22 degrees out and falling to 15 tonight. My 19’ chimney, 10 of which is single wall, drafts much harder at 20 than at 60 ambient temps.

So many variables that impact draft significantly. Actual flue length may not even be the biggest.

 

[71montess]

In at least a few instances, retailers have reported to me EPA contacted them to find out how many dampers they sell. It has been a few years (3-5) since I have heard about these inquiries.....maybe they read your post!!

Or maybe the autocrat at the EPA, who was inquiring about the dampers, got fired or retired !

 

[71montess]

I agree with you, although I've tried pointing it out in the past and have been met with a lot of opposition because people don't want "complex computers" on their simple stoves.

I'd go out and build such a stove myself if it wasn't so expensive to get the stove certified for emissions or a UL listing.

The reality is the operator is the primary factor in poorly performing stoves (which includes the operator burning wet wood), followed by a non-typical install. Automation can remove the operator (mostly) and compensate for a less than ideal install, but it still doesn't help if wet wood is used.

The reality is the "final EPA 2020 emissions standard" can't be final, there has to be improvement, for now the burning of coal, diesel and gasoline vehicles are still taking much of the blame for poor air quality. As EVs become more popular and coal is continued to be phased out wood heat will again attract attention for its contribution to lowered air quality. There will need to be another improved step for wood stoves emissions to allow wood heat to continue in the coming decades. I simply don't see how this can improve without automation of the controls.

Get practical, common sense people hired at the EPA and other environmental agencies ?

 

[SpaceBus]

Written by some Govt. agency, so clear as mud, right ??
I installed 2 key dampers in my 35’ stack (and somedays could use a third) for my King..
My argument would be.. I’m not trying to alter the low burn rate at all, I’m trying to achieve those draft specs !!

No, it was certainly written by humans trying to describe the issue with as much specificity as possible in the event the text is contested in a court of law.

 

[TradEddie]

As an active participant in these forums, I often see references to the use of dampers. I receive PM's and emails from consumers every once in a while asking if they should install a damper. I don't respond to those inquiries.

As a manufacturer, we follow the Federal Register (law) as it pertains to the proper installation of our appliances. When the subject of dampers comes up, I tend to not respond for the above reason.

When a manufacturer tests a wood heater, they are required to test it as they will manufacture the product. Any modifications to air intake or exhaust that would enable the appliance to operate at a lower burn rate than as it was tested are illegal. So forgive me, but I am not trying to be evasive on such inquiries or posts, just sticking to the letter of the law.

Here is the actual wording from the 2015 NSPS. Yes, it's awkwardly written, but the intent is clear...with multiple follow-up conversations.

View attachment 288687

This paragraph has no legal bearing on the installation or use of dampers. This paragraph simply makes it illegal to manufacture a stove that doesn't include this warning in the manual. I might assume there's some other regulation that codifies the claim in this warning, but that's by no means certain.

TE

 

[BKVP]

This paragraph has no legal bearing on the installation or use of dampers. This paragraph simply makes it illegal to manufacture a stove that doesn't include this warning in the manual. I might assume there's some other regulation that codifies the claim in this warning, but that's by no means certain.

TE

I'll provide the precise reference as it applies to "use", but it clearly addresses the non commercial owner. The Federal Register categorizes 1) manufacturers 2) commercial owners (dealers, distributors) 3) non commercial owners (end users)

There are very specific references within the text that apply to proper use and conformity with what is published in the manual.

A good illustration, when owner's of OWB, an EPA defined exempt heater prior to 2015, did not install or use them correctly, local regulators were able to take action. Being emissions exempt did not exempt owners from proper installation and use according to the manual.

Of course few enforcement action are generally taken against non commercial owners. It's much easier and focused to seek compliance from manufacturers.

One additional observation. Prior to 2015, Owners & Operators Manuals were not regulated. Now they are reviewed and must be approved by EPA. When the test labs conducts emissions tests, they are to operate the heater per the Owner's & Operators Manual.

 

[Trevor Tahclep]

"The Series B device is driven by a predictable increase in chimney updraft at the beginning of Stage 2 due to the rise in exhaust temperature when the gasified resins ignite. The increased updraft draws a balanced pivot plate open, uncovering an intake opening to provide the "boost air" needed to ensure complete combustion of the volatile gases. Unlike the original EBT device, which delivers the boost air to the primary fire, the new device feeds the extra air to the secondary flames only. The operator retains control of the burn rate of the primary fire, and longer burn times are easier to achieve." courtesy of Tom Oyen

I understand the 2nd generation EBT works allowing more air or full air into the secondary at the beginning of stage 2 then restricting airflow to prolong the coaling stage and extend overall burn time. I don't see how this could prevent over fire during the secondary stage. Most of us with tall chimneys need to reduce daft during that part of the fire. The only way I see this being able to work is if it closed the primary air at the same time, but I am not sure would prevent an over fire, that would increase fire box temps?
On a Lopi freedom I tried decreasing primary and secondary air I mostly had I ended up with less complete combustion, lots of soot on glass. The only thing that helped slow the burn and lower stove top temps during the second stage was closing a flu damper.

According to the importer of Pacific Energy products in Australia the EBT2 is a draft breaker.

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[BKVP]

The first was from a wonderful, talented Kiwi gentleman. Brian developed the VCV well over a decade ago and approached many manufacturers about integration into their products. After no successful integration, they built and certified their own stove. Hats off to them....down under determination!

 

[fire_man]

Woodstock has a bimetallic coil control of secondary air and PE uses a barometric control of secondary air. Of course BK runs all intake air through a thermostatically controlled throttle body.

You’re right, this could be taken care of on the intake side.

Which Woodstock Stove has a bimetallic coil control?

 

[BKVP]

Which Woodstock Stove has a bimetallic coil control?

 

[fire_man]

Wow I didn't know WS added that to the Absolute Steel! Now they have alien technology too!

 

[BKVP]

Wow I didn't know WS added that to the Absolute Steel! Now they have alien technology too!

It's different. Helps with start up emissions, so it's semi-alien....hee, hee...

 

[fire_man]

I just hope these stoves never go computerized/electronic. I know there is talk in the industry of fine tuning woodstove emissions electronically.

I fully subscribe to the KISS theory.

 

[begreen]

The first was from a wonderful, talented Kiwi gentleman. Brian developed the VCV well over a decade ago and approached many manufacturers about integration into their products. After no successful integration, they built and certified their own stove. Hats off to them....down under determination!

View attachment 288901

Yes, I was hoping to see the Kiwi VCV 2 for sale. I like the design because it self regulates and doesn't depend on stove body heat like a thermostatic coil does. On a cold startup, it can take a while to warm the mass of a stove even though the firebox can be raging. The EBT2 is similarly draft regulated, though just on the secondary. I thought this was the first stove to meet EPA 2020 standards. At 77% efficiency, it qualifies for the tax credit. I thought he was working with Ben Myren(sp?) on the product. Did that fizzle out?

 

[EatenByLimestone]

They can eliminate the different chimney/different draft issue by eliminating chimneys. Then we have big pellet stoves.

 

[BKVP]

Yes, I was hoping to see the Kiwi VCV 2 for sale. I like the design because it self regulates and doesn't depend on stove body heat like a thermostatic coil does. On a cold startup, it can take a while to warm the mass of a stove even though the firebox can be raging. The EBT2 is similarly draft regulated, though just on the secondary. I thought this was the first stove to meet EPA 2020 standards. At 77% efficiency, it qualifies for the tax credit. I thought he was working with Ben Myren(sp?) on the product. Did that fizzle out?

BeGreen, you are spot on. I hesitate here to mention full names, but yes, Ben was his point of contact here stateside.

I remember very well standing in the booth as the device was demonstrated. It was explained to EPA staff that by simply sliding the brass stop on the shaft, the stove could be tuned to a specific installation. I don't think I need to tell you what happened next.

But at dinner that night, the conversation focused solely as I have posted numerous times, it has to me made, tested, certified and lastly installed precisely as tested.

This entire thread is predicated upon ZERO customization of the wood heater once it certified.

I hope you can make it to ATL this year for Expo. It's been a while.

BKVP

 

[BKVP]

They can eliminate the different chimney/different draft issue by eliminating chimneys. Then we have big pellet stoves.

Or, sell the heater/chimney as a package. Still won't allow for over drafting, unless the entire system is sold as tested.

 

[john26]

According to the importer of Pacific Energy products in Australia the EBT2 is a draft breaker.

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He called it a draft breaker but didn't explain how it works, but according to Tom's website in hi draft conditions the metal tab is drawn open to add secondary air then closes as draft falls off this would be the coaling stage. I would like to hear from someone who has a PE with EBT2 on a 25' plus chimney and how the secondary flames react and if any overdraft occurs.

 

[Trevor Tahclep]

Extremely interesting reading.

(broken link removed to http://forgreenheat.org/2018-stovedesign/award.html)

 

[ABMax24]

VcV (Variable Choke Venturi) Emissions Reduction System Update and Cord Wood Testing Commentary Prepared By: Myren Consulting, Inc. 4/16 for presentation. - ppt download

What is the VcV System? VcV’s are simple mechanical devices that operate using the static pressure in the stack 2 VcV’s / stove, possibly 3 Primary VcV – operates mainly on “Low”. “Foolproof” 2nd VcV – operates over the entire burn rate range Each operates differently but all work together to...

slideplayer.com

 

[jdonna]

https://forgreenheat.blogspot.com/2018/06/meet-teams-new-zealand-entrepreneur.html?m=1

I’d gladly as an end user pay the 50.00 licensing fee to have this level of custom draft control on a stove!