OWB vs IWB for new contruction

[E Yoder]

Several manufacturers made some huge changes in OWB gasification units in the last 5 years or so and have really cleaned up the smoke issues. The G series is legal in New York so no worries there.

 

[SpaceBus]

What happens when a gasification OWB needs to idle?

 

[peakbagger]

"Legal" and friendly to a local environment in the real world is two different things. The EPA testing is for steady state combustion with standardized seasoned cut and split wood. I agree that when there is demand for heat from the house the new EPA OWB boilers are potentially far cleaner if operated and fueled as designed. Where the problem lies is when there is no demand for heat and the boiler is operated typically where the owner loads it up full to minimize loading cycles with poorly seasoned unsplit logs. Especially in shoulder seasons the boiler is mostly running in idle with no heat demand. When its idling the boiler is not running hot enough for the low emissions design to work unless the owner deliberately puts in a dump coil to keep the boiler over some minimum load. I have had no experience operating the new style but I have heard second hand reports that folks are bypassing various functions intended to make the boiler burn clean so that they can run them easier. I cant verify it, but suspect that's the case with some OWB designs as I see references to the same tricks on EPA stoves (Magnets or permanent plugs to plug the hidden air ports to get longer burns). The only way to get a clean burn for cordwood is eliminate idle time when the stove is below minimum combustion temperature and have intermittent long batch burns of dry wood so the boiler gets up to adequate temp for full combustion and stays there until the wood charge is gone. This means adding significant thermal storage and controls which tends to destroy the economics of OWBs. I have known a few air regulators and universally they wish OWBs never came on the market as in real world as typically operated they tend to be nuisance.

 

[SpaceBus]

There are a few depressing YouTube videos of folks touting their OWB units and bragging about the ability to burn long unsplit pieces of wood. I would recon at least half of the rounds the chap in the video loaded to be over 1.3 Cuft each. The video clearly shows the OWB running at full demand and the stack is pouring steam like a freight train. Conveniently no mention of idling or what happens when the house is warm.

 

[Medic21]

What happens when a gasification OWB needs to idle?

Same as my 7300MP. It shuts off all incoming air and sits there. That is why both need a good coal bed to run properly

"Legal" and friendly to a local environment in the real world is two different things. The EPA testing is for steady state combustion with standardized seasoned cut and split wood. I agree that when there is demand for heat from the house the new EPA OWB boilers are potentially far cleaner if operated and fueled as designed. Where the problem lies is when there is no demand for heat and the boiler is operated typically where the owner loads it up full to minimize loading cycles with poorly seasoned unsplit logs. Especially in shoulder seasons the boiler is mostly running in idle with no heat demand. When its idling the boiler is not running hot enough for the low emissions design to work unless the owner deliberately puts in a dump coil to keep the boiler over some minimum load. I have had no experience operating the new style but I have heard second hand reports that folks are bypassing various functions intended to make the boiler burn clean so that they can run them easier. I cant verify it, but suspect that's the case with some OWB designs as I see references to the same tricks on EPA stoves (Magnets or permanent plugs to plug the hidden air ports to get longer burns). The only way to get a clean burn for cordwood is eliminate idle time when the stove is below minimum combustion temperature and have intermittent long batch burns of dry wood so the boiler gets up to adequate temp for full combustion and stays there until the wood charge is gone. This means adding significant thermal storage and controls which tends to destroy the economics of OWBs. I have known a few air regulators and universally they wish OWBs never came on the market as in real world as typically operated they tend to be nuisance.

You need to look at the new Gasification OWB since you obviously haven’t a clue. Heatmaster and Crown Royal both have no way for the stove to sit and dump anything when waiting for a call to run. Even with the load bypass open it won’t do anything for making heat.

 

[Medic21]

There are a few depressing YouTube videos of folks touting their OWB units and bragging about the ability to burn long unsplit pieces of wood. I would recon at least half of the rounds the chap in the video loaded to be over 1.3 Cuft each. The video clearly shows the OWB running at full demand and the stack is pouring steam like a freight train. Conveniently no mention of idling or what happens when the house is warm.

yes, large rounds in a conventional cause a lot of smoke. i dropped a dead tree yesterday and verified the moisture at 21% in some of them by splitting a few in half. it smoked when I loaded it and cleaned up in 10 min. The rounds are anywhere from 4” to 18”.
The gasifiers won’t take a large round like that. The reason I went with what I have is to have the ability to burn coal. If I split 6” and load right I can get a 12hr burn that’s fairly clean. During idle it has no smoke at all because it shuts off all air. Trick is setting that to not suffocate the fire completely and still have coals to retire.

 

[peakbagger]

Same as my 7300MP. It shuts off all incoming air and sits there. That is why both need a good coal bed to run properly




You need to look at the new Gasification OWB since you obviously haven’t a clue. Heatmaster and Crown Royal both have no way for the stove to sit and dump anything when waiting for a call to run. Even with the load bypass open it won’t do anything for making heat.

Okay, you are obviously selling and I and others are not buying. I will let the OP make up his own mind knowing that he is two states away so i dont have to put up with the inevitable stench.

 

[maple1]

Same as my 7300MP. It shuts off all incoming air and sits there. That is why both need a good coal bed to run properly




You need to look at the new Gasification OWB since you obviously haven’t a clue. Heatmaster and Crown Royal both have no way for the stove to sit and dump anything when waiting for a call to run. Even with the load bypass open it won’t do anything for making heat.

The dumping thing could be done with any boiler, if desired. It's not a boiler function but rather an aspect of system design.

 

[Medic21]

Full load, at idle for another 30-40 min.

 

[maple1]

Full load, at idle for another 30-40 min.
View attachment 252413View attachment 252414View attachment 252415

I think when coming off idle it would put some smoke out?

 

[Medic21]

Okay, you are obviously selling and I and others are not buying. I will let the OP make up his own mind knowing that he is two states away so i dont have to put up with the inevitable stench.

Not selling anything. Look up a G series and compare the emissions, per hour not when burning at max only, and compare them to IWB. You might be surprised that they have to meet the same standard now for residential use.

I just did the research for installing my system this year instead of opinions. I get it that you’ve had a bad experience. More than likely a conventional boiler installed in a residential area. Stupid, only an idiot would do that and it should be regulated.

Of you spend the time looking at any data on a gasifier OWB you would find efficiencies upwards of 80%. That’s better than a lot of LP furnaces that are still in service at 60% because they were built to last then.

You are spewing old information.

the Crown 7200E is cleaner burning than the Econburn.

 

[Medic21]

I think when coming off idle it would put some smoke out?

very much so. It’s a Conventional. I live in the middle the country if I lived in a residential area I would put gasser in. There are a lot of people that have no clue how far the new gassers Have come in outdoor wood boilers.

 

[Medic21]

Looks like the Crown 7200E is even cleaner than the comparable Garn for what he’s heating.

@peakbagger would you like to find some data and testing information to debunk the EPA’s own data?

 

[maple1]

I don't know, so that's why I'm asking. Does the testing include idling and coming out of it? For boilers not required to have storage?

 

[Medic21]

I don't know, so that's why I'm asking. Does the testing include idling and coming out of it? For boilers not required to have storage?

I’m not real familiar with indoor units with large storage. These outdoor units have close to 300 gallons. I would think every single one my conventional included would put some smoke out whenever they fire if nothing else It needs to clean out the firebox and get fresh air in it.

I try and get mine to runTwice an hour on a load of good Drywood it runs 10 to 15 minutes and then shuts off after the first hour it cleans up and pretty much has no smoke after loading.

The downdraft gasser units pretty much have to burn clean or they won’t burn the way they’re designed. They are not a secondary burn.

 

[Medic21]

@maple1 ive been told by guys running the G series and Pristine stoves that 4 hours idle is about the limit so they don’t go out.

 

[3fordasho]

Here is the start up for doing a batch burn in a indoor style downdraft gasification boiler (hydronic heater- we hope to not boil anything ;-)

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[3fordasho]

part 2 (sorry I don't know how to edit to make this one video)

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[Karl_northwind]

heatmaster and Crown are both forced downdraft. The G series from Heatmaster have an awesome bypass blower system for loading.

my five second inspection on any new boiler I see on the market is whether it's induced draft or forced. if it's induced I'm still listening, if it's forced (air blowing into the fire rather than sucked thru and sent up the stack) I don't bother.

the heatmaster units are induced, which means the blower is at the
base of the chimney.

 

[HitzerHillbilly]

I feel like conventional OWB’s are despised on this site. That being said, I didn’t have $13-$20K for an install so I purchased a used conventional Heatmor. Bottom pic is at idle, middle pic is it just starting to cycle, third pic is approximately 5-7 min after the cycle starts. I wouldn’t necessarily say it’s smoking like a freight train. Actually seems like it generally smokes less than my Hitzer insert did. Now if I throw a full load of green wood in, then yes it smokes. As will any stove, and you wouldn’t want to throw green wood in a gasser.....indoor or outdoor. Now I also live in the middle of nowhere so neighbors aren’t really an issue. As far as the stench.....I kind of like the smell of a wood burning stove, call me crazy.


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[Bad LP]

I came home to Ma from Me today and pass a few OWB. They were all smoking and I’m glad they are not near me.
Seeing a yard full of rounds tells me more than I need to know about what’s being burned.

 

[Medic21]

my five second inspection on any new boiler I see on the market is whether it's induced draft or forced. if it's induced I'm still listening, if it's forced (air blowing into the fire rather than sucked thru and sent up the stack) I don't bother.

the heatmaster units are induced, which means the blower is at the
base of the chimney.

The Pristine is the same way. I researched both heavily when looking.

 

[Medic21]

I feel like conventional OWB’s are despised on this site. That being said, I didn’t have $13-$20K for an install so I purchased a used conventional Heatmor. Bottom pic is at idle, middle pic is it just starting to cycle, third pic is approximately 5-7 min after the cycle starts. I wouldn’t necessarily say it’s smoking like a freight train. Actually seems like it generally smokes less than my Hitzer insert did. Now if I throw a full load of green wood in, then yes it smokes. As will any stove, and you wouldn’t want to throw green wood in a gasser.....indoor or outdoor. Now I also live in the middle of nowhere so neighbors aren’t really an issue. As far as the stench.....I kind of like the smell of a wood burning stove, call me crazy.


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mine will smoke like crazy with very dry wood worse than 20%-25% wood. It’s a balancing act to learn how to run it decent. My neighbors that are close enough to smell anything have all told me they love the smell from when I was burning inside. The MP is still cleaner than my original furnace in the basement.

 

[HitzerHillbilly]

mine will smoke like crazy with very dry wood worse than 20%-25% wood. It’s a balancing act to learn how to run it decent. My neighbors that are close enough to smell anything have all told me they love the smell from when I was burning inside. The MP is still cleaner than my original furnace in the basement.

I threw some green wood in a couple weeks ago and it smoked a lot during its first cycle


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[HitzerHillbilly]

I hope the OP is still interested in a stove after this thread.


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