Pacific Energy's EBT Technology

[thechimneysweep]

In the "Burn Times" thread below, someone cited my website as one place to read about Pacific Energy's Extended Burn Time apparatus. They say ignorance is bliss, and when I wrote that description ten years ago I must have been blissed out.

Frank Ivy's post later in the thread caused me to visit the EBT patent materials online, after which I contacted PE with more questions. It turns out my understanding of the PE tech guy's description of how EBT worked was a little skewed.

The bimetallic coil does open and close an air shutter independent of the manual draft control setting, but at opposite times than I had earlier reported.

I have corrected the page to reflect my new understanding of the EBT apparatus. Anyone interested can view the new page at (broken link removed)

 

[Rhone]

Your site is amazing Tom! For a site that doesn't have a forum I think I've logged more hours than any other there. You'd be amazed how often people point to it and learn from it, I've caught myself spending a few hours in the sweep's library now and again.

 

[Willhound]

Thanks Tom

Your revised explanation gives me a clearer understanding of how this works, particularly with the "third" charcoaling stage of the fire. Apoligies to Rhonemas and Frank Ivy for my arguments to the contrary. They were essentially trying to state what you have outlined, just not in a form that I could understand or accept. I love a good debate, but I'm also man enough to admit when I'm wrong.

Willhound

 

[Roospike]

Ah , Pacific Energy I'm sure just got a flood of emails . I just got back my email from P.E. on how the EBT worked from when i emailed them 2 days ago about it. I was for sure that the EBT unit opened at the point of needing more air to burn in the secondary burn chamber on the overnight burn. It just didnt make sence that someone thought (posted) the EBT was closed the whole time to get the longer burn times. I can also see on my free standing PE summit that the main air and the EBT gets its "own draft" and they are not hooked togother a the same air supply. thechimneysweeps web page says it in a way we can "understand how it works." and in what steps it take to work . Now i can sleep at night ...........aw, OK , it wasnt that bad. Good post TCS

 

[Roospike]

Frank"o" Less coffee bud ............ I though it made sence from the start. you thought you would put on your boxing gloves about it. When i said on this thread "thechimneysweeps web page says it in a way we can “understand how it works.” and in what steps it take to work ." NOW that one could read it right there and not have to cut through all the B.S. back and forth of the fourm to figure it out for them selves. Hey Frank ............Does the EBT make sence to you now ? LOL

 

[Willhound]

EDIT

One of the logs I was throwing in the fire actually grew a mouth and some eyes, looked up at me, and in a stiff, slow voice said, "that makes sense."

Saddam Hussein called. He said nothing makes sense anymore, except what Frank Ivy wrote. "What Frank Ivy wrote," he said, "made sense even to me, Saddam Hussein."

My dead grandmother just channeled in to me. She said, I quote, "that's just plain horse sense boy! You wanna longer fire? Lower down the air supply!"

Scooby phoned in. He said, "rat rakes rense." I didn't even give him a Scooby snack or anything.

Johny Cochran also chanelled in. He said, "the man makes sense, so get off the fence."

Frank
Sometimes you scare me. People on this forum are bound to make off the cuff remarks from time to time. I know that for myself, I can't always be bothered to go back through all the posts and see exactly who said what. Sometimes I do, but sometimes I don't, it's not a full time job. But, I can see that you were being a little tongue in cheek here and I laughed my "ash" off at the part of your post shown above.

The Scooby thing especially just killed me. :lol:


Willhound

 

[thechimneysweep]

Just a little clarification about the EBT mechanism: the manual draft control and the EBT apparatus are one and the same assembly. If you look at the lower right corner of the sketch I've attached (if it doesn't come through, you can view it on my website at (broken link removed to http://www.chimneysweeponline.com/hoebt.htm) ), you'll see a little cut-off tab attached to the bottom "leg" of the EBT flapper support. This tab is the primary draft control handle, located under the ash tray of the Summit. When you slide this handle left and right, the entire EBT assembly moves left and right with it.

In the sketch, the flapper is shown in the open position. Visualize the flapper in the closed position, with the left side of the v-shaped plate down and covering the intake hole. Now, see how if you were to slide the manual draft control to the right (open) position, the plate would slide off the hole, opening the air intake? This action also slides the right side of the flapper out of reach of the actuater rod coming from the bimetallic coil, so that when you have the draft control set to full open, the EBT, which isn't needed when the draft is open, can't operate.

So when your stove is cold, and the EBT flapper is closed, you need to manually slide it off the intake hole by moving your draft control to the right to give your fresh load the air necessary to get the fire going, just as with any woodstove. After the wood is kindled, you can slide the draft control back to the left (low) position for the long burn, which moves the right side of the flapper into position so the actuater rod from the bimetallic coil can reach it and open the flapper as needed to supply extra air to the fire.

 

[Willhound]

So when your stove is cold, and the EBT flapper is closed, you need to manually slide it off the intake hole by moving your draft control to the right to give your fresh load the air necessary to get the fire going, just as with any woodstove. After the wood is kindled, you can slide the draft control back to the left (low) position for the long burn, which moves the right side of the flapper into position so the actuater rod from the bimetallic coil can reach it and open the flapper as needed to supply extra air to the fire.

Tom
I assume that the draft control has a pivot point? Such that when you slide the control handle to the right, the end of the handle, or "tab" as shown in the diagram slides to the left, and vice versa? The draft control handle on my Summit insert has the low setting to the right, and the high setting to the left, opposite of what you describe.

Willhound

 

[thechimneysweep]

Ooops. Sooner or later, I'm going to learn to have the coffee, then post to the forum. Yes, the draft control rod is "pinned" to the stove on a pivot point so that when you move the lever to the right the mechanism inside the stove moves to the left.

 

[Willhound]

S'okay. I usually have had a pot full of coffee before I check the forum, therefore my thoughts race ahead of my typing ability and as a result my
"thoughts ahead of my typing jumbled become".

 

[ermite]

Tom Oyen, what are you talking about again. Look at a summit stove and you will see that the ebt system and the draft control are not linked and are two independent units. WHEN YOU DO NOT UNDERSTAND SOMETHING please do not try to explain it to others like you do in your site.

 

[thechimneysweep]

I published the description of the EBT mechanism shown above after speaking at length with a tech support person who either didn't understand it herself, or didn't describe it correctly, or was simply unable to formulate a clear enough description to penetrate the high density matter at this end. The EBT mechanism opens and closes an intake hole separate from the draft control.

It turns out the single-mechanism description wasn't the only thing I got wrong during that conversation. I spoke to PE's head of technical services today, and he says my recent modification regarding how and when the mechanism opens and closes, which was prompted by a discussion on this forum regarding the description that accompanies the patent, was also erroneous. He said I had that part so right on my original web page that he actually sent people who called PE tech support about the EBT technology to my site to read the description. I have now restored that part.

Apologies to all on the forum who have been misinformed about the EBT by my previous postings. You can view the revised revision, officially approved by PE's Technical Department, online at (broken link removed to http://www.chimneysweeponline.com/hoebt.htm)

 

[Willhound]

Does this mean I get to take back the apology I made to Frank and Rhonemas (above) and instead insert
"Na, na, na, na, na" ?

 

[thechimneysweep]

Willhound, according to what PE told me today, your understanding of the mechanism was right on from the get-go. The discussion on another thread at the time about how the patent for the hardware reads differently might have been accurate, but the same assembly can be used to either open or close the pivot plate at temperature, depending upon the orientation of the coil, and PE verifies that the implementation of the patented mechanism in the Summit series woodstoves opens the extra intake whenever the stove cools below lightoff temperature, as I had originally reported.

 

[DavidV]

here's a quick question. Does the thing burn cleanly?

 

[ermite]

Tom Oyen, what are you talking about again. I have a summit stove on 4 legs and i have dissasemble the cover under the ebt system so i can see the intake hole and the pivot plate. SO I KNOW HOW IT WORKS BECAUSE I CAN LOOK AT THE HOLE WHEN THE STOVE IS IN USE. When the stove is cold,the trap is close,this is a fact.The trap open only when the stove is very hot on the base and it close again when it become cold. It works exactley like the patent explanation.It provide more air only when the stove is hot on the base.STOVE COLD,TRAP CLOSE. STOVE HOT, TRAP OPEN.
WHEN YOU DO NOT UNDERSTAND SOMETHING please do not try to explain it to others like you do in your site.

 

[thechimneysweep]

The description of how the EBT technology works came from Pacific Energy's head of technical support, who's name is Ken (don't know his last name). He can be reached at (250) 748-1184. Ken explained to me that a briskly burning (hot) fire doesn't need additional air, and remarked that adding extra combustion air to a briskly burning fire could quickly lead to overfiring. According to Ken, the way the EBT mechanism extends the burn time is to allow you to adjust the mechanical draft control on its lowest possible (longest burn) setting without fear of smoldering. If the combustion temperature inside the firebox should fall below secondary lightoff level, the EBT opens up and supplies air to the fire until it comes back up to temperature.

Ermite, let's say you just added a full load of wood to your fire and opened your draft control all the way to kindle it, then got distracted, left the room and forgot to close it down. If your observation of the EBT mechanism is correct, the coil would respond to the high temperatures created by the resulting raging fire and OPEN UP to add even more air. Can you explain what you think the reason for that function might be?

 

[Willhound]

Uhhhh...by letting it burn? Frank we've been around and around this merry-go-round a couple of times already.

I believe my post in the Burn Times thread covered it. What is it that just does not allow yourself to believe that occasionally someone else might be right ?

If Tom says he got the right poop from the right person (finally) at P.E., then what makes you think he's wrong? Are you calling him a liar?

What Tom describes makes a lot more common sense to me than your argument that EBT "cuts" air. If that's the case, just close your damper and let her smolder.

Willhound

 

[thechimneysweep]

The problem with big fireboxes and non-catalytic EPA combustion systems is control of the fire. Wood stoves must meet the EPA emissions requirements even when the draft control is set as low as it can go, and large fireboxes are hard to run at low settings and still maintain secondary lightoff temperature. Many manufacturers have "solved" this problem by creating draft controls that don't shut down very far. This allows the stove to burn briskly enough to pass EPA testing at the low setting, but supplies way more air than the fire needs during certain stages of the burn, which has the affect of shortening the burn time.

The EBT technology allows Pacific Energy to give the consumer more draft control into the low end, thus improving burn times. If the fire becomes too starved for air at this low setting (indicated by a drop in temperature), the EBT opens up and supplies just the amount of air needed to bring it back up to critical temperature.

Referring to the attached sketch, notice that the bent end of the actuator arm has rotated to the 3:00 position, where it has pushed Side A of the pivot plate backward to lift Side B all the way off the intake opening. This happens only within a specific temperature range which occurs during fireup and cool down.

Here's my understanding of how the EBT mechanism works through all stages of a freshly-lit fire:

1) No fire. Stove is at room temperature. The EBT mechanism is closed ( The bent end of the actuator arm is at the 12:00 position, Side A of the pivot plate is in the vertical position, and Side B of the pivot plate is covering the intake hole).

2) Fire Started. The manual draft control is opened wide to kindle the fresh load. The firebox temperature rises. As it does, the bimetallic coil warms up and begins to rotate the actuator arm clockwise, moving the bent end downward from the 12:00 position toward the 3:00 position. As the firebox temperature rises, the bent end on the actuator arm encounters the upright side (Side A) of the pivot plate, gradually pushing it backward to raise Side B and uncover the intake hole, allowing extra air to the freshening fire to help bring the firebox up to secondary combustion temperature.

3) As the firebox temperature continues to rise, the bimetallic coil continues to rotate the actuator arm. When the bent end passes the "high center" position at 3:00 shown in the sketch, its continued rotation towards 6:00 begins to move the bent end away from Side A, gradually lowering Side B back toward the intake hole.

4) If the firebox approaches the high-limit temperature, the bent end of the actuator arm rotates beyond the contact point with Side A at the 6:00 position, allowing Side B to drop down all the way and cover the intake hole to prevent overfiring.

5) At this point, the load is kindled and the manual draft can be set to the low position for the all-night burn. With the air supply now severely limited, the flames diminish and the firebox begins to cool, causing the bimetallic coil to rotate the actuator arm in the opposite direction, so the bent end moves from 6:00 towards 3:00 .

6) As the firebox continues to cool, the bent end of the actuator arm once again encounters the upright Side A, gradually pushing it backward toward the "high center" position at 3:00 to raise Side B and provide extra air. The extra air makes the fire burn hotter, to ensure secondary combustion temperature. As this temperature is reached, the rotation of the actuator arm reverses, and the bent end of the actuator arm rotates toward 6:00 and away from Side A, once again lowering Side B toward the intake hole.

7) Once the fire stabilizes into this temperature range (basically Stage Two of the burn), the actuator arm continues to rotate the bent end so it travels between the 12:00 and 6:00 positions, gradually raising and lowering the pivot plate just as much as needed to maintain minimum secondary burn temperatures. This ensures the longest possible burn time for Stage 2 of the fire while maintaining EPA emissions levels.

8) When the fire has burned down to charcoal stage, there are not as many unburned gases left to require reburning, so it becomes less and less necessary to add combustion air. During the charcoaling stage, the firebox gradually cools to the point where the bent end of the actuator arm rotates off Side A at the 12:00 position, lowering Side B to cover the intake hole. The only air entering the firebox during this final stage of the fire is the small amount allowed by the manual draft control at its low setting, which ensures the maximum duration of the charcoal stage of the fire.

 

[webbie]

ChimneySweep, that is the most incorrect yet.

Will - Chimney Guy - Neither of you has explained how adding more O2 to a fire will "extend" a burn. Care to?

I don't have the smarts or time to wrap myself around this stuff, but my red flag goes up anytime anything is explained in code - like EBT.......

MANY stove companies have used many forms of temperature control using bimetallic coils - all the way from Ashley to Vermont Castings and others.... Blaze King is another western manufacturer who uses a coil and claims proven burn times as long as 40 hours.

It's hard to imagine that Pacific or any other manufacturer has tested this technology independently with every possible type of wood and chimney. After all, the radiant qualities of eastern wood species are very different than that of western woods.

As it stands now, only verified tests by independent labs can really test or verify any of these claims - and even then, the lab bills are paid by the manufacturer and often the test setups are also specified by the maker....

In defense of "EBT" and similar technologies, didn't the Defiant Encore with thermostat test out as one of the highest efficiency stoves? If so, then there might be something to this "in a perfect world"....whether it works on an everyday basis in Joes house is another thing....

 

[Willhound]

Frank
It wasn't meant to be personal. On the other hand, your previous post (below) I think is somewhat personal. And no, I'm not trying to be Tom's defender. I think he's done a very capable job of doing that himself.

Still wrong.

If you're right, please explain how introducing more air to a fire makes it burn longer.

Also, please provide the name of the PE person to whom you spoke.

OK, so he's given a very well written explanation regarding how the introduction of more air helps just as it is needed as well as how when the air is no longer needed it is cut back. He's also given you the name you asked for.

You? You've done nothing but continue to stick to your original assumption, in the face of evidence to the contrary. Hence my earlier question regarding not being able to accept a contrary point of view.

Yes, please, talk to Ken. The only thing that will settle this once and for all is some kind of first hand official acknowledgement from P.E. about what this thing is, and what it does. Get him, or better yet, the guy that invented it, to post, even as a one time thing. I can understand them not wanting to be on here all the time. I'm sure we'd drive them crazy.

As a matter of fact, I for one have no further desire to argue this point as I feel it serves no useful purpose. So until I see something direct from P.E. that contradicts what Tom has outlined, I quit.

 

[ermite]

Tom Oyen, what are you talking about again. You are changing your explanations every days and you still wrong.HERE IS HOW YOU WILL (PERHAPS) UNDERSTAND THE SYSTEM EBT.You take a summit stove like the one i have.You dissasemble the little cover under the ebt unit so you can see the intake hole.You put wood in it and you light it. Then you will be able to see how it works. It works just like the patent explain and to answer at your question:Yes if you forget the draft control full open,the pivot plate will open untill it contact the stop and will stay open untill the temperature drop. It is not a safety device.It is a system permitting a big wood stove to pass epa test even if you have closed the draft control to low and it can extend the burn time because it close during the first stage and the charcoal stage.If you take a other stove like the super 27 of pe you do not have ebt because it is not a large box so it is not big enough to put enough wood for extra long burn times.Also if you let the draft control of the super 27 full open,you will cause the same dangerous overheating of the stove.

 

[thechimneysweep]

Frank, I never said PE wasn't using their own patented device. Of course they're using it, that's what this thread has been all about. If you reread my most recent post, you'll see that I'm not talking about PE's USE of their patent, but PE's IMPLEMENTATION of the patent, which makes clever use of the device to both increase and decrease supplementary combustion air, only as needed. As to how the device increases burn time by sometimes adding air, it only adds air when the manual draft is set too low to supply adequate combution air to sustain secondary lightoff temperatures, which means it creates the longest possible EPA approved burn. Without the device, PE would have had to limit how low you can set the manual draft (as so many other manufacturers have done with their larger non-catalytic models), which would result in the shorter burn times the owners of those models complain about. As to your statement

"I think the EBT closes down air flow as an overnight burn starts to cool down. This not only is exactly what the patent says, it also is what physics says"

Your statement is not incorrect, as far as it goes, but more precisely, the EBT closes down only the airflow it had previously opened up to provide. Follow the steps in my description above, and you'll see that a better description of the device's function is to ADD combustion air as needed. When the overnight burn cools down to the point where the bent end of the actuator arm loses contact with Side A, the EBT's pivot plate is essentially deactivated for the duration of the burn (no additional air is provided), control reverts to the manual draft, and if that contol is on its lowest setting, the longest possible Stage 3 results.

Ermite, PE doesn't like to discuss their implementation of the patent in detail, for obvious reasons, (which is one reason I've had a hard time getting a handle on it) but I ran my most recent post by their tech department guru, and he said I have the concept down. If you want to verify, his name and number appear in that post. I don't believe you have observed the mechanism constantly throughout an 8-hour burn on the low manual draft setting, but you do choose to do so, and the mechanism doesn't perform as described above, contact your dealer for warranty service.

 

[thechimneysweep]

Wrong -

Sweep wrote: "As to how the device increases burn time by sometimes adding air, it only adds air when the manual draft is set too low to supply adequate combution air to sustain secondary lightoff temperatures, "

No. It functions entirely independently of the draft lever.

When the coil gets hot, it opens. When the coil gets cold, it closes. That simple.



So, Sweep, what you are saying is that the "Extended Burn Technology" adds air when the fire "needs it", which of course would shorten the burn.

If you are correct, then the device is misnamed.

Frank, the EBT functions independently of the manual draft lever, but it is the setting of the manual draft lever (specifically the low burn setting) that creates the temperature change in the firebox that brings the EBT mechanism into play. If you keep the manual draft control open enough to sustain secondary combustion temperatures, the EBT won't open up to supply supplemental air.

Your statement that when the coil gets hot the EBT opens and when the coil gets cold it closes isn't accurate. When the stove is cold, the EBT is closed. As the stove heats up, it opens gradually until lightoff temperature is achieved. If the stove starts to overheat, it closes gradually until the temperature returns to a safe level.

As to your contention that adding supplemental air at certain times shortens the burn time, either you haven't been reading my posts very carefully, or I haven't been doing a good job explaining things (which I'll admit is quite likely). So I'll try again.

Let's say you want to build a stove that achieves the maximum possible burn time for its firebox size. You could weld up an airtight firebox with a tight sealing door, and incorporate a draft control that could shut down the flow of combustion air all the way. Then, to achieve the ultimate burn time, you could get your fire kindled up and slam the draft control all the way shut, cracking it open just enough to keep the fire smoldering along. You'd get incredibly long burn times for each load of fuel, but the unburned exhaust gases would billow out the chimney at criminal levels.

If you did that, you'd achieve the longest possible burn, but you wouldn't be able to sell your stove in the US due to the EPA emissions regulations.

So let's say you want to build a stove without the EBT technology, and want it to achieve the longest possible burn without creating unacceptable emissions levels (like today's manufacturers must do). You could insert a temperature probe into the stove, load and kindle your fire, and wait until lightoff temperature was reached. Then, to achieve your long burn, you could crank the manual draft control down to its lowest setting. Then, you could monitor the secondary combustion temperature and, if it started to fall below lightoff level, crank the manual draft open a bit to supply more air until the temperature came back up to lightoff level, then tweak the draft back down for the long burn, repeating these moves as necessary throughout the second stage of your burn. Because the fire would change character throughout the burn, you wouldn't be able to stop tweaking the air supply until charcoal stage was reached and you could set the manual draft to low for the duration.

If you did that, you would have achieved the longest possible EPA approved burn, giving the fire just enough air to stay clean-burning but no extra air to shorten the burn time.

And that's exactly what the EBT mechanism does.

 

[webbie]

If you did that, you would have achieved the longest possible EPA approved burn, giving the fire just enough air to stay clean-burning but no extra air to shorten the burn time.

And that's exactly what the EBT mechanism does.

Wow, 33 posts about a relatively simple device.....

I would think the above explains a LOT - That is, LONG BURN STAYING WITHIN AN ACCEPTABLE EPA OR CLEAN RANGE. Most manufacturers do this by simply not allowing the air control to be tight or else leaving a certain amount of secondary air flowing.

Heck, maybe this stuff IS rocket science!

A 1980 vintage stove called the Patriot used the bimettalic to shut the fire down as stove got too hot - therefore making UL approval easier. I have not studied the EBT patent, but given the long history of such thermostats in stoves it might not hold up in court - luckily, our industry is small enough that it probably won't either be copied or have to be defended. After all, many stoves have been able to pass EPA and better without it.

Sensors have been used in many types of heating equipment to provide similar function.

Can't expect Patent Agents to know much about the "lost" history of the thousands of early stove models...Sometimes I wonder if patents are like fashion styles - that is, every number of years the same things repeat themselves and no one is the wiser!