Initial Draft Readings for Pacific Energy Summit LE Insert - Cause for Concern?

[davidmsem]

The primary air on modern stoves does not close down 100%. It will always admit a little air, this is to prevent smoldering the fire.

Interesting. The lever on my unit, when closed, covers the primary air hole 100%.

 

[EbS-P]

Interesting. The lever on my unit, when closed, covers the primary air hole 100%.

Wish my Drolet insert did that. But since yours has the boost air the effect is the same but yours is easier to plug. My boost air is on the air control plate

 

[begreen]

Interesting. The lever on my unit, when closed, covers the primary air hole 100%.

I see, had to look this up. It is interesting. The new air intake design is different from what was standard on PE stoves for decades. I installed a 2020 PE T6 a couple of years ago. I will have to see if they will let me peek under the ashlip to see if this is for all the large firebox PE stoves, or just the insert. This has my curiosity piqued.

 

[davidmsem]

Question regarding secondary air flow and ebt2.

If one were to reduce the flow going into the EBT2 unit, how would one know what is the right amount of airflow to block? One indication I think would be the overall draft. After blocking the boost air, in order to get the unit within the drafts back of 0.1 in column of water, that would be one indication I presume. Is there any indication of cutting it back too far? Fire behavior? Exhaust air flow temperatures in the flu etc?

Curious in Connecticut.

Thank you.

David

 

[begreen]

The EBT is self-regulating. I would leave that alone unless absolutely necessary. It's best to not tinker too much with the stove. There is a risk of adding too many variables which can lead to tail chasing if there are issues. The Summit is a robust burner. Work with it for this season and get to know how it performs under all conditions.

 

[EbS-P]

Well with the ebt2 you could reduce the total draft of the system and never actuate the ebt regulator flap. Same I guess could happen if you just blocked the secondary air intake. One might be able to use your damper and be able to hear the flapper close. Open the damper the flap should close??? Just guessing. If it doesn’t close maybe it’s been blocked too much. I found it difficult to keep the appropriate primary :secondary ratio. I would target lazy secondary fames at the last 1/3 of my burn cycle. They probably should still get a bit blow torch like under a full, hot, high (but still normal) draft burn.

Edit… is it time to start thinking about restrictor at the top of the liner? It would help keep the primary/secondary balance

 

[davidmsem]

The EBT is self-regulating. I would leave that alone unless absolutely necessary. It's best to not tinker too much with the stove. There is a risk of adding too many variables which can lead to tail chasing if there are issues. The Summit is a robust burner. Work with it for this season and get to know how it performs under all conditions.

Understand. Just trying to anticipate colder days and what she may do and have a plan in place.

 

[begreen]

The EBT has a small hole that always admits a little air to the secondary as long as there is some draft. Blocking off the secondary feed on an EPA stove is not a good idea. It would really mess with efficiency and emissions. The primary air control now has a minimum air hole next to the valve that is about 3/8" in diameter. This system replaces the older air control design like on our stove.

Regulate the stove with the current flue damper and air control. The burn may get more lively in very cold weather, most of our stoves do. But that is also a time when we want more heat. I run our stove about 100-150º hotter in very cold weather. Learn to control the fire by burning thicker splits, packing the firebox tightly, and closing down the air in a timely manner.

Hogwildz has some good data in old threads on the Summit insert temps and operation that can be used for reference. The link I provided earlier shows our stove running in winter on a 20' flue system.

 

[davidmsem]

Well with the ebt2 you could reduce the total draft of the system and never actuate the ebt regulator flap. Same I guess could happen if you just blocked the secondary air intake. One might be able to use your damper and be able to hear the flapper close. Open the damper the flap should close??? Just guessing. If it doesn’t close maybe it’s been blocked too much. I found it difficult to keep the appropriate primary :secondary ratio. I would target lazy secondary fames at the last 1/3 of my burn cycle. They probably should still get a bit blow torch like under a full, hot, high (but still normal) draft burn.

Edit… is it time to start thinking about restrictor at the top of the liner? It would help keep the primary/secondary balance

Thank you for the reply. I'm just thinking ahead to when I have a full load on a cold day. The smaller test fires I had drafted at 0.16 to 0.18, with a requested limit by the manufacturer at 0.1. this was with the damper closed and boost air blocked. So I've already changed the mix of primary to secondary by having a llmore secondary flow than primary with the boost air blocked. I'm assuming blocking secondary would bring it back into balance and help with the draft being over spec.

I think the next step would be restricting the secondary but I'm not entirely sure. I'm not sure of the efficacy of a plate at the top. The restriction at the damper is well over 90%, I'm guessing. I'm wondering how much of a restriction you are thinking about on the top of the flu?

Overall I'm entering this season in the best shape in 7 years I've been burning with the help here.

I'm an engineer for 35 years and tinker with jet engines. Tinkering is what we do and it does become a disease I understand.

But I sense there's going to be more room for improvement. Blocking the secondary is very easy I don't have to get on a huge ladder which I don't think I would do anymore. Right now I'm trying to gain a sense if I do block that, what would be the signs of over-construction? There are two holes in addition to the EBT2 rotating baffle. They are analogous to the boost air for the primary.

Thank you for the reply.

 

[brenndatomu]

I'd really try to reduce draft further rather than blocking more passageways on the stove...keep the factory primary/secondary balance as much as possible (beyond blocking the boost air)
I think I'd really consider finding/making a damper plate that fits tighter than the one you have now...or maybe the top of chimney restricter cone that was mentioned...

 

[begreen]

Agreed. One option, if necessary, could be putting a 6" x 5" reducer on top before the cap, but I would run it for a season and learn how to manage the stove before making more changes.

 

[davidmsem]

I KNOW @begreen will not be happy, but please understand you are dealing with an engineer.

It was 36 degrees last night and very cool today, so I decided to run an experiment.

I neatly packed some of the high temperature rope that is used to seal the door to a fireplace unit. I then slid the "wad of rope" under the EBT2 (secondary air extended burn) inlet. I DID NOT plug the two holes on the side of the EBT2 unit.

I fully loaded the firebox and started a top down burn.

A few hours in, with the primary air lever opened about 10%, the unit is steady state cruising as follows:

1) Primary air opened 10%
2) Exhaust gas temperature 10-12" up flue - STEADY at 600 degrees.
3) Drafting at 0.1 in-column of water (decrease from 0.16 without secondary EBT2 doorway opening restricted).
4) Face temperatures above the door 350ish.
5) Lazy secondary burn flames. No secondary flames "shooting out of the holes", but lazy and steady.

Sooo different from my old Regency I3100. As configured today, my concerns for the Pacific Energy are with respect to running the unit too cool and building up creosote. The I3100 would have run up to 700 degrees face temperature with a full load and 10% primary air opened IF NOT HIGHER. In addition, the run time would but much shorter for the Regency I3100L.

I suspected the prior draft number of 0.16 (with smaller loads) was due to the secondary air feed since we blocked the boost air. Draft DID not go down much when I blocked the "boost air" hole feeding the primary air location. So I figured the secondary airflow needed some restriction as well. The unit now runs (on a 40 degree day) at the spec limit of 0.1 in-col of water.

It appears to me that I'm getting closer to a better running configuration, with concerns about "choking the unit to run too cool".

What a difference with this setup.

I appreciate thoughts (other than getting yelled at for tinkering). I'm an engineer, which is a disease, not a career.

David

 

[stoveliker]

Regarding the secondary flames, different from the tube jets, I would go out and look at the chimney. Clearly you are burning gases. But are you burning all? Do the old "can I see smoke" test - for (chimney cleanliness) safety.

 

[davidmsem]

Regarding the secondary flames, different from the tube jets, I would go out and look at the chimney. Clearly you are burning gases. But are you burning all? Do the old "can I see smoke" test - for (chimney cleanliness) safety.

Thank you. My education continues....

 

[stoveliker]

Not education, just an engineering observation that the proof (that all works fine) is in the pudding (i.e. what comes out of the chimney). Better look and see an issue than fond out because of deposits in the chimney.

This does lead to the "is it smoke or steam" issues, but it's warm enough that I think steam is not yet visible.

If you see something that looks like smoke (steam dissolves in air in a few feet max, smoke dilutes and remains visible longer), unplug a secondary air inlet that you plugged now, see the jets appear, and then have another look(5 mins later or so) to see if things have changed (possible smoke disappeared).

Engineering feedback is done thru observations (or measurement - but that you have already implemented well here).

 

[EbS-P]

I do think journey is an example of how the design parameters for new 2020 regulations are limiting user control and are really designed to operate under a certain draft conditions that can easily be exceeded and not brought under control (back into draft spec) even with a full plate damper in the closed position. I really don’t think inserts on a two story 6” liner is that out of the ordinary.

Following along. I’m guessing I will find myself figuring out how to further reduce draft on my insert. It will see more burning this winter.

 

[begreen]

I would let the EBT do its thing. There will be some fountains of fire coming below the baffle during peak burn. That is because the wood is outgassing strongly and the stove is working aggressively to burn off the volatiles. This is by design and only lasts for about 30-45 minutes. After that, the EBT flap closes and a more gentle billowing of secondary flames continues. 350º on the stove face is a bit cool. Don't be afraid to take it up hotter. It's a robust design.

 

[begreen]

I really don’t think inserts on a two story 6” liner is that out of the ordinary.

It's a design choice where most Canadian designers seem to favor making their stoves perform well in single-story homes. Some American-made stoves have longer secondary air intake paths with 90º turns that require stronger draft. They tend to work better in 2 story homes but often need a 3' extension on a single-story chimney if it is only 12-13' tall. This is a generalization of course. There are exceptions.

 

[davidmsem]

I would let the EBT do its thing. There will be some fountains of fire coming below the baffle during peak burn. That is because the wood is outgassing strongly and the stove is working aggressively to burn off the volatiles. This is by design and only lasts for about 30-45 minutes. After that, the EBT flap closes and a more gentle billowing of secondary flames continues. 350º on the stove face is a bit cool. Don't be afraid to take it up hotter. It's a robust design.

Thanks @begreen .

With a draft of .16, I don't think the EBT flap closes. I think it remains opened. I would love to have the spec number on when the EBT flap closes.

With the EBT door closed, and a very small fire, damper closed, primary air 100% choked, exhaust temperatures reach 700°. So I'm not so sure about opening up the EBT and letting it draft more, especially with a full load.

I do have some secondaries going, occasional fire out of some of the holes. I think the worst I'm doing is polluting a little bit, but I'd rather have a controlled safe burn temperature wise.

Once again the draft with the EBT door blocked is 0.1, the manufacturer spec. There are two holes in the EBT chamber that I did not block.

 

[begreen]

Is the EBT flap open when the stove is cold? Is the manometer reading a draft of .16 after an hour or two into the burn or does that number decline by then? If it is just reading high at the peak of the burn then I would say it's doing its job.

 

[davidmsem]

Is the EBT flap open when the stove is cold? Is the manometer reading a draft of .16 after an hour or two into the burn or does that number decline by then? If it is just reading high at the peak of the burn then I would say it's doing its job

Is the EBT flap open when the stove is cold? Is the manometer reading a draft of .16 after an hour or two into the burn or does that number decline by then? If it is just reading high at the peak of the burn then I would say it's doing its job.

With the EBT door unblocked, the draft remains at 16 or slightly higher for hours.
The EBT door is designed to work within manufacturer's operating spec with a maximum draft of 0.1. We are exceeding that by 60% in my unit.

I can certainly confirm what I was observing again for consistency and confirmation.

I appreciate your comments.

David

 

[davidmsem]

Is the EBT flap open when the stove is cold? Is the manometer reading a draft of .16 after an hour or two into the burn or does that number decline by then? If it is just reading high at the peak of the burn then I would say it's doing its job.

3/4 load today, raw rainy day. Draft at 0.1, primary air 100% closed, exhaust gas temperature cruising at 850ish, face temp above door averaging 500ish.

This is part of why I'm hesitant to open up the EBT port.

 

[begreen]

What was it reading 1 hr later?

 

[davidmsem]

What was it reading 1 hr later?

Draft was holding at 0.1 and temp slowly dropping. Just guessing that temp was 750. Pure guess. Plateau was 850ish.

Can you see why I don't want to open the EBT port?

 

[begreen]

Sort of, but remember, you are measuring flue temp right at the flue outlet so it's bound to be on the high side. How does the temperature on the face of the insert above the door look?