Secondary Burn

[Whitespider]

You have provided no data to support your assertions...

Ummmm..... where's your "data"??
But yes... I used the wrong wording when I posted, "In other words, fuel input and combustion efficiency is used to calculate per hour output."
It should have been, fuel input and heat output (and/or heat lost through the stack) is used to calculate efficiency... but the BTU value is stated/listed/advertized/marketed/etc. on a per hour basis. None of that changes the point I was making... regardless of the fuel mileage my pickup gets at 10 MPH
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[Cerran]

Ummmm..... where's your "data"??
But yes... I used the wrong wording when I posted, "In other words, fuel input and combustion efficiency is used to calculate per hour output."
It should have been, fuel input and heat output (and/or heat lost through the stack) is used to calculate efficiency... but the BTU value is stated/listed/advertized/marketed/etc. on a per hour basis. None of that changes the point I was making... regardless of the fuel mileage my pickup gets at 10 MPH
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And the older stoves put more flow and total BTU's out the stack per unit wood burned (not to mention unburned hydrocarbons).

 

[Chris-PA]

It should have been, fuel input and heat output (and/or heat lost through the stack) is used to calculate efficiency... but the BTU value is stated/listed/advertized/marketed/etc. on a per hour basis.

The combustion efficiency is how much of the energy contained in the fuel is extracted and sent into the room - there is no time term in the equation at all and it therefore cannot be converted into a rate.

The energy output rate manufacturers list is a separate spec and cannot be compared to the efficiency rating. It is also likely a peak output, and will not hold true over the entire burn time as Cerran pointed out earlier. It might not even last for an hour, as I could calculate BTU/hr over a 5min period. Or it could be total BS because it isn't 3rd party tested and there is no truth in advertising.

 

[Locust Cutter]

To the one point Cerran made, what do you do when you've bought one of the largest stoves on the market and you still come up short, especially in regards to the Mfct's stated heat capabilities in regards to area? When the company says 2-3,000sqft and it doesn't affect 1,000 the way I'm looking for leaves me a bit more than disappointed.

 

[Cerran]

To the one point Cerran made, what do you do when you've bought one of the largest stoves on the market and you still come up short, especially in regards to the Mfct's stated heat capabilities in regards to area? When the company says 2-3,000sqft and it doesn't affect 1,000 the way I'm looking for leaves me a bit more than disappointed.

Then I would think something is wrong.

Also remember that the manufacturers rating is also based on a well insulated house and a specific exterior temperature.

 

[mn woodcutter]

Then you must have a poorly insulated house because my Pacific Energy Fusion is rated for 1200-2000 sq ft. I heat our 3300 sq ft house without a problem unless it's well below zero outside. We have lots of open space on both floors so I'm sure that helps and some big south facing windows which doesn't hurt. My experience with this stove has been nothing but smiles!

 

[cmsmoke]

Groundhogs day, over and over and over.

 

[Whitespider]

Groundhogs day, over and over and over.

Yeah... no kiddin'... same ol', same ol'... day in, day out.

And here's the proof...

 

[Chris-PA]

Yeah... no kiddin'... same ol', same ol'... day in, day out.

And here's the proof...




View attachment 386914

Why do you keep posting pictures of the thermostat connected to your wood furnace, as if it were relevant in a discussion about the differences between two types of wood stove? Are you intentionally trying to bury a discussion in which your arguments have been shown to be false?

All you are "proving" is that heating systems exist that can hold a house at a steady temperature in mild weather - while utterly failing to support your contention concerning what is wrong with secondary combustion wood stoves and why they cannot be used to heat a house.

My house was about 75deg yesterday, all on a couple of tiny splits in a secondary combustion stove with a 1.34 cu. ft. firebox.

 

[mn woodcutter]

Yeah... no kiddin'... same ol', same ol'... day in, day out.

And here's the proof...




View attachment 386914

Hahaha. It's spring time weather right now! I've had windows open for the last couple days!

 

[Whitespider]

Why do you keep posting pictures of the thermostat connected to your wood furnace...
My house was about 75deg yesterday, all on a couple of tiny splits...

Truthfully, the last time I added fuel to the box was 45 hours ago, a couple splits on Saturday just after lunch... the box is stone-cold dead.
The "furnace" wasn't the point... I was responding to the Groundhogs Day thing.
Why would you have a fire if your house was 75°??

Likely I'll start a small (real small) fire before turnin' in tonight, the warm spell is gonna' come to a quick end overnight... mid-20's by mornin' and holdin' steady all day with 25-30 MPH NW winds, mid-teens by the next mornin' and barley breakin' 20° that day, we ain't supposed to even see 30° all week.
This short spring was nice... but winter is comin' back.
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[fixit1960]

Mine's been so full they fall out when ya' open the door

Once those coals ash-over, very little air can get to 'em... the heat output virtually ends. If a' don't keep stirring 'em every 10 minutes or so, they just die out and ya' end up shoveling a bucket load of charcoal chunks out the next day. And stirring 'em just mixes 'em with ash, which makes it even harder to burn 'em up. It's a lose-lose proposition... either freeze your azz off while you're screwin' 'round for 3 hours trying to burn the coals up, or just bite the bullet and toss out a bucket load of unburnt fuel. I got sick of screwin' 'round... I just toss the coals out.

By-the-way... the problem ain't unique to PE. I know of 4 other elitist stoves, all from different manufacturers, that do the same damn thing... and the colder it is outside, the worse the problem gets. (Although, just goin' on posts from this board over the last couple years, PE seems to be a bit more prone to such problems.)
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I don't know about anyone else but if I had to babysit the wood burner as your describing I would get rid of the POS. Seems like they have designed it (or lack of design) to make only the retired, "oh I have nothing else to do" segment of society a customer prospect. How in the world could a person use it for a primary heat source if you had to sit and tend it? Unless it's designed for those who don't work or have a life?

 

[Chris-PA]

Why would you have a fire if your house was 75°??

Perhaps the same reason you ran your stove in your shop when it was 40°? Except that my smaller stove worked just fine.

Seems like they have designed it (or lack of design) to make only the retired, "oh I have nothing else to do" segment of society a customer prospect. How in the world could a person use it for a primary heat source if you had to sit and tend it? Unless it's designed for those who don't work or have a life?

Interesting presumptions. Perhaps the fact that I am not retired and we using secondary combustion wood stoves as our only source of heat would show that they are false. We have no back up system at all.

 

[Cerran]

I don't know about anyone else but if I had to babysit the wood burner as your describing I would get rid of the POS. Seems like they have designed it (or lack of design) to make only the retired, "oh I have nothing else to do" segment of society a customer prospect. How in the world could a person use it for a primary heat source if you had to sit and tend it? Unless it's designed for those who don't work or have a life?

WS's experience seems pretty atypical based on the feedback here and on the hearth boards. My experience in helping with 7 installations of wood stoves (cat and non cat versions) is that the modern stoves output the same amount of heat or more for generally less wood. How much is debatable but I would say on average 20-30% less wood.

The biggest complaint I have heard from people who switched is that the new stoves don't turn down as far as their old stove which is true, a minimum air level is set to prevent choking the fire down too much.

My experience says that cat stoves are the way to go if you want maximum burn time, and non cat stoves are the way to go if you want a more simple operation. Or as in my case the quad was one of the few stoves approved for a factory-built fireplace install.

That being said, there does seem to be a problem with certain stove models and coal buildup over time which may or may not be wood dependent. Since there is no good data as to these installations their location, chimney height, or good wood data diagnosing whether it's the stove itself or how they are being operated is impossible.

 

[513yj]

I don't know about anyone else but if I had to babysit the wood burner as your describing I would get rid of the POS. Seems like they have designed it (or lack of design) to make only the retired, "oh I have nothing else to do" segment of society a customer prospect. How in the world could a person use it for a primary heat source if you had to sit and tend it? Unless it's designed for those who don't work or have a life?

I hear a lot of positive praise about the EPA stoves from the warmer climate folks and I concur, especially when it's milder here. Spider has a valid point as well and I second his opinion from personal experience. One thing I've noticed is I haven't seen a lot of the Canada boys on here talking about how good their secondary burn stove is. Prolly because it's colder up there than it is here and to make it work well you have to burn a lot more wood in the cold.

 

[fixit1960]

I hear a lot of positive praise about the EPA stoves from the warmer climate folks and I concur, especially when it's milder here. Spider has a valid point as well and I second his opinion from personal experience. One thing I've noticed is I haven't seen a lot of the Canada boys on here talking about how good their secondary burn stove is. Prolly because it's colder up there than it is here and to make it work well you have to burn a lot more wood in the cold.

I agree somewhat with both your and Cerrans response to my comment. My issue is that the EPA will regulate away the ability to purchase and run the "old style" before all the bugs are worked out of the new design EPA approved models. I don't believe in the climate change theory and don't have concerns about "wood economy". I burn scrap pallet wood for the most part in an OWB that is 1/4 mile from my nearest neighbor, I have a 30 ft stack and in 15 years no one has ever commented on the smoke output it has when cycling the first 4 or 5 times after filling. When I have to replace mine in 5 or 15 years I would like to have the same choices (or more) that I had 15 years ago when I bought this one. In the warmer, milder climate the new style may work fine and be everything that they are said to be, but in the colder climates where I feel they are needed more, if they will not perform correctly I don't feel as if I should be forced into the purchase of one. Here again my fear is the government telling me what my choices are because someone thinks they know my situation better than I do.

My Heatmore distributor told me that next years models similar to what I have will come with a modified upper pass which will be basically tubes instead of an open area the length of the fire box. These tubes will collect particulate which will require shutting down periodically depending on the type of wood and the moisture content in order to scrub the tubes clean. Not very user friendly. I can't wait until it's -15 and a 30 mile an hour wind out of the north and I have a shop full of work and the upper pass plugs.

 

[Chris-PA]

My Heatmore distributor told me that next years models similar to what I have will come with a modified upper pass which will be basically tubes instead of an open area the length of the fire box. These tubes will collect particulate which will require shutting down periodically depending on the type of wood and the moisture content in order to scrub the tubes clean. Not very user friendly. I can't wait until it's -15 and a 30 mile an hour wind out of the north and I have a shop full of work and the upper pass plugs.

I'm somewhat skeptical that this is a good description of how this will work - I don't see how tubes would be made to collect particulates. It sounds more like they would add secondary burn tubes as in many stoves, which are tubes that have small holes allowing fresh air to be introduced into the top of the firebox to burn the particulates. This reduces output of particulates and converts it to energy. I certainly could be wrong though as I can't know what they might be developing.

 

[cmsmoke]

Yeah... no kiddin'... same ol', same ol'... day in, day out.

And here's the proof...




View attachment 386914

That wasn't the intent of my reply...There is only one FL here and it's not me.

 

[fixit1960]

I'm somewhat skeptical that this is a good description of how this will work - I don't see how tubes would be made to collect particulates. It sounds more like they would add secondary burn tubes as in many stoves, which are tubes that have small holes allowing fresh air to be introduced into the top of the firebox to burn the particulates. This reduces output of particulates and converts it to energy. I certainly could be wrong though as I can't know what they might be developing.

I like you idea better but have no way of knowing other than what the dealer told me. That would make sense and they use forced air combustion so it could be done that way easy enough. When I asked him the purpose of the tubes he said to collect particulate. My response was what happens when it is full, and he said you shut it down enough to clean it. Maybe I wasn't getting the full story from him. He did mention that the person he was talking to (factory rep/dealer) indicated it would not tolerate green or wet would very welll after the design change. That leads me to believe it isn't a secondary burn as with the forced air and enough heat, plugging would not be problem. I'm not in the market for a new OWB so I never pursued it. Just relaying what I was told.

 

[Oxford]

Those tubes are going to plug. I don't know why they're adding them, but there are only two reasons. Either they're trying to extract more heat from the flue gases by adding tubes, thereby improving the technology from the 1650's to the 1850's, or they're adding tubes to catch particulates by increasing surface area contact of the flue gases, basically encouraging sooting as a pollution control method. In a gas or oil fired boiler, sooting is to be avoided at all costs as an indication of bad combustion tuning, but since the outdoor boilers have terrible combustion tuning by default, this could be a really bad, cynical way of trying to improve their flue emissions. It's not the four or five times a day the thing goes to high fire, it's the 20 hours a day that it's the combustion equivalent of a tire fire that are the problem. Increasing exhaust path length, coupled with really low velocity since the blower won't be running during those times, might encourage the particulate matter to just fall out of the air stream.