OWB vs IWB for new contruction

[NorthernNY]

Hello everyone, I am looking at building a house within the next 2-3 years and want to heat with radiant heat and use wood as a fuel source. The plan is to heat the house (est 1500 sq ft to start) and an unattached 2 car garage with the system.

So what I am looking for are any recommendations or experiences with OWB and IWB. I have done some preliminary research and understand the difference and some pros and cons between the two.

For OWB I am looking at a gasification unit and brands like Central Boiler, Heatmaster and Crown Royal. Any other brand experiences would be appreciated. I like the OWB because it keeps everything out of the house, is a fairly simple install and has a large firebox for long burn times.

For IWB I am also looking at a gasification unit and have found brands like Econburn, Froling, any others would be appreciated. Negatives I see with these units are shorter burn times, slightly more complicated install and the large storage capacity required with them.

Questions:
People with IWB how do you like them and how long are your burn times / how frequent are fires required??

Additionally what do you use for storage and how much $$$ do you have in storage tanks??

OWB people, What gasification boilers do you own?? What do you love/hate about them and what kind of burn times are you getting??

I've cut and burned wood pretty much my whole life in traditional wood stoves so i'm familiar with the process and want some personal experiences with these types of systems.

 

[3fordasho]

I've just installed an IWB in an outbuilding that itself has average wall and ceiling insulation. My storage tanks were spray foamed about 2", tanks were boxed in with 1.5" foam on back wall and floor, R13 on studded walls around tanks and R16 on the top. Every inch of copper to and from boiler and loop to house is insulated. Even with that the 24 x 48' outbuilding the boiler/storage set up is in was at a comfortable 58F with 30mph north winds this morning and 25F outside. That is with no heat emitters in that building - just what escapes from storage/piping. It's been a real eye opener and I would be concerned about those losses with a OWB no matter how well insulated.



So to answer a couple of your questions - Storage - 2-500 gallon propane tanks. Sourced from local propane supplier who had scrap tanks for a cost of $200 each. Scrap tank because of missing tag or rust or some other defect that makes it unusable for propane.
About 40 hours of my labor to make them suitable for use ( cut 20" square opening in top for cleaning inside, weld on radiused patch, 2- 1.75" hole sawed holes, weld in additional tank ports- lots of leak checking).

As far as the boiler, it's an Attack DPXL-45 lamda controlled 45kw boiler from newhorizonstore.com - no complaints and would purchase the same unit again. I've only had the system on line a couple weeks but once I got storage up to temp I can easily do one burn in the evening and a partial load at that (disclaimer -not that cold yet and just because I like to watch a fire in the house I do still burn my wood stove in the evening). So besides heating the building the boiler is in from standby losses, the loop feeding the house needs to heat 3400 sq ft via a pair of water to air heat exchangers installed in a FA propane furnace.

 

[NorthernNY]

I've just installed an IWB in an outbuilding that itself has average wall and ceiling insulation. My storage tanks were spray foamed about 2", tanks were boxed in with 1.5" foam on back wall and floor, R13 on studded walls around tanks and R16 on the top. Every inch of copper to and from boiler and loop to house is insulated. Even with that the 24 x 48' outbuilding the boiler/storage set up is in was at a comfortable 58F with 30mph north winds this morning and 25F outside. That is with no heat emitters in that building - just what escapes from storage/piping. It's been a real eye opener and I would be concerned about those losses with a OWB no matter how well insulated.

View attachment 252256View attachment 252257

Thanks for the reply, I really like the look of your system and I am also concerned about the heat loss and inefficiencies of a OWB vs keeping the heat in a more usable space. If you don't mind giving some details on your system, what kind and size of boiler are you using?? How much storage do you have and what are you using for storage tanks?? How long do you go between firings when the weather is like today??

 

[3fordasho]

Thanks for the reply, I really like the look of your system and I am also concerned about the heat loss and inefficiencies of a OWB vs keeping the heat in a more usable space. If you don't mind giving some details on your system, what kind and size of boiler are you using?? How much storage do you have and what are you using for storage tanks?? How long do you go between firings when the weather is like today??

Attack DPXL-45 boiler, rated 45kw (~153Kbtu)
Storage 2 x 500 gallon propane tanks, horizontal configuration but stacked, 1000 gallon total storage.
Only 2 weeks online so not much data yet as to how often this will need to be fired , so far have not fired more than once per night, maybe 2/3 load, except for initial bringing storage up to temp and that was 2-3 loads. Boiler has ~6.9 cubic foot firebox. This boiler has 28-30" deep firebox and all my wood is cut to ~18" so I'm not getting ideal loading in there.

 

[Karl_northwind]

I've been running a heatmaster G-200 for 3 years now, and I like that the mess is outside. I am heating a 2500 sf well insulated house and a 1400 SF very poorly insulated stone barn.

If the weather is above the single digits, i load wood twice a day, and it's about 1/3 a firebox each time. when the weather drops below say 5 degrees, it takes nearly a full load twice a day (the barn is kept at 40, so the heat load goes up fast when the temp drops from 20 to 5F) and when it's more than 5 below zero, it's two full loads a day (morning, and bedtime,) plus a third partial load when coming home from work at 5 so there is still a nice coal bed when the 10PM load goes in. this has been with marginally dry wood, 25% ash and maple, and a little oak. This year I expect to do much better with dry wood, oak, maple, and ash.

I have been burning about 6 cords of un seasoned wood a year here in central wisconsin, burning thanksgiving to end of march, will be burning longer this year due to the cold snap, but expect to burn about the same since I have seasoned wood here now. not that we had much of a summer to dry wood out, but it's better than previous years splitting wood in november for the winter.

I lose some heat from the stove, but the space requirements for an indoor burner were a non-starter, and I sleep better with the fire 100 feet from anything irreplaceable.

I've installed and serviced a lot of indoor and outdoor boilers, and thus far, I think the G-200 has been my best experience with any of them, from a service, maintenance and efficiency standpoint.

Full disclosure: I am a heatmaster dealer. I think Crown makes an ok gasifier, we'll see how they hold up because they are brand new design, just going into their second season in the field. I've heard they've had to change a few things, and the EPA listing is still the old model, so the emissions/ efficiency numbers are unknown to most of us.

for as small a space as you're talking about a G-100 would be OK, if you're not going to add a bunch of load. That's typically a 3 cord a year boiler if it's heating a couple thousand well-insulated square feet.

 

[hobbyheater]

Have been heating with a Jetstream and 1,000 imperial gallons of storage since the early 80's ,if Garn had been around when I started its a Garn I would of had .

GARN | High-Efficiency Gasification Wood Boiler and Thermal Storage in One Unit

Simple system low maintance and probably one of the most efficient.

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[maple1]

Trying to compare burn times, or attaching relevance to them when deciding on a boiler, gets into misleading territory and isn't much use. An indoor gasifier with storage might have a shorter burn time than something else you're comparing to, but it will put a lot more heat into the water for pounds of wood burned. Burn times might be a decent talking point with wood stoves, but not boilers - extending boiler burn times just usually means choking it down and smoldering and making smoke & creosote.

Check out Varm via Smokeless Heat. Prices on their website. I have one in my basement, wouldn't do it any other way. 660 gallons of storage (2 x 330). Storage cost will depend what you can find locally, mine was around $800-1000. Mid-winter I burn 6-8 hours a day, once a day. That usually consists of build & light a fire, load full after 20 minutes, re-load full 4 hours later. Or thereabouts.

 

[NorthernNY]

Have been heating with a Jetstream and 1,000 imperial gallons of storage since the early 80's ,if Garn had been around when I started its a Garn I would of had .

GARN | High-Efficiency Gasification Wood Boiler and Thermal Storage in One Unit

Simple system low maintance and probably one of the most efficient.

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Thanks for the Garn recommendation I am deff interested in that type of single unit system and type of longevity. Any other Garn users thoughts would be greatly appreciated

 

[NorthernNY]

Trying to compare burn times, or attaching relevance to them when deciding on a boiler, gets into misleading territory and isn't much use. An indoor gasifier with storage might have a shorter burn time than something else you're comparing to, but it will put a lot more heat into the water for pounds of wood burned. Burn times might be a decent talking point with wood stoves, but not boilers - extending boiler burn times just usually means choking it down and smoldering and making smoke & creosote.

Check out Varm via Smokeless Heat. Prices on their website. I have one in my basement, wouldn't do it any other way. 660 gallons of storage (2 x 330). Storage cost will depend what you can find locally, mine was around $800-1000. Mid-winter I burn 6-8 hours a day, once a day. That usually consists of build & light a fire, load full after 20 minutes, re-load full 4 hours later. Or thereabouts.

I would say at this point I am more concerned with firing times, I want a system I don't need to fire or reload every 4 hours because i can be gone between 8 and 20 hours a day for work. I am becoming more and more interested in the indoor boilers with storage the more I hear from people on this site. I will deff check out Varm.

 

[maple1]

I would say at this point I am more concerned with firing times, I want a system I don't need to fire or reload every 4 hours because i can be gone between 8 and 20 hours a day for work. I am becoming more and more interested in the indoor boilers with storage the more I hear from people on this site. I will deff check out Varm.

My schedule above has flexibility. Usual routine is make fire late afternoon, reload 3-4 hours later, fire out or almost out when I'm on my way to bed. If real cold, throw another half or full load in then. The bigger the boiler (more room for more fuel each load) and storage, the more flexibility, generally speaking.

There are also tricks to use in your routine. I also use setbacks (only a couple degrees or so) on some of my zones to extend time between burns. And time things so they set back up when I am lighting my fire. So the heaviest heating load, is when I'm burning. And I usually heat the house or parts of it a bit warmer than usual, when burning - kind of like using the house for some storage too. Sizing your emitters for lower supply temps, or using lower temp emitters (in floor, or panel or cast iron rads) can also extend your storage and time between burn potential. I have ordinary baseboard, which usually needs higher supply temps, but have concluded it was oversized when designed & installed. Which turned out to be a very good thing. Since that also helps when recovering from a setback.

 

[Bad LP]

I get a kick out of some who are afraid of the boiler inside yet have no problem with a wood stove burning.

I wouldn't take an outdoor boiler if it was free. I'm not putting my boots and jacket on to trudge out to the boiler 100 feet away in -25weather and the wind blowing. All my heat loss is inside the building envelope and the house was designed to store wood inside a walk out garage. There is a set of double doors from that garage space to the actual basement. Makes it easy to move wood, equipment like saws, cabinets and even my Bridgeport miller was moved into the basement by myself.

If you are building from scratch its easy to make changes on paper now. Think about how YOU intend to like in YOUR house.

For my detached garage it's roughed in for a LP burner in the 2 bay area and I have some high bay infrared heaters for the big bay. Someday I'll hang the equipment when I got nothing to do. LOL

 

[gfirkus]

Look at the Switzer boiler if you want an all in one unit. Built in Dundee ny. I have a 1400 gal unit and burn about every 2 days in winter. Below 0deg is once a day. 2009 modular home 1500 sq ft unfinished bsmt. I did the install myself. Gary Switzer can help with design.

 

[Medic21]

I’m running a Crown Royal conventional. I like having the ability to burn coal is the only reason I didn’t go with a gasser. Crown Royal and Heatmaster have the best customer support, hands down. Central Boiler pretty much is horrible.

open vs closed system is really what your looking at. If you do an OWB install a propane boiler inside as backup. The G series from Heatmaster I believe is the only UL listed boiler for indoor installation. That said it would have to be an outbuilding because insurance will not allow it in a garage anywhere I have checked.

A G200 from Heatmaster or 7200E from Crown will do what your heating nicely. Set up your indoor system and use a 50 plate exchanger for the OWB and you’ll be set if you ever can’t cut or load wood.

After burning inside for 3 decades Ihave no problem going outside to load.

 

[salecker]

Econoburn makes an outdoor unit.It is basically the same as the indoor unit with more insulation and a metal shed around it.
I have one which ironically ended up as an indoor unit.I didnt know how long it would take to get my boiler building finished,it was in stock and i got a good deal.
I personally would never have a fire burning appliance in my home,there is no Fire Department where i live,so having the flame sources out of my house is my fire insurance.
I have no problem going outside at -40C to go to stoke the fire.It needs to be filled after 3 hour burn,so not a big deal to go outside.All the mess and danger is seperat from my home which is worth the walk.Plus i have a warm workshop 24/7 all winter long to work in.No mess in my home from dirty chainsaws,stinky snowmachines,dusty wood working ect.Plus the fact i never have to worry about carbon monoxide poisoning is worth every cold and miserable walk if there are any.

 

[NorthernNY]

Look at the Switzer boiler if you want an all in one unit. Built in Dundee ny. I have a 1400 gal unit and burn about every 2 days in winter. Below 0deg is once a day. 2009 modular home 1500 sq ft unfinished bsmt. I did the install myself. Gary Switzer can help with design.

Thanks for the info I have never heard of this brand and am very interested in an all in one unit and local support

 

[peakbagger]

While you are making the choice, keep this in mind, OWBs are restricted or banned in parts of the country as they can become a nuisance to the neighborhood. New York has special regulations in place that homeowners are required to comply with and any one installing and operating an OWB are opening themselves up for future liability when the boiler inevitably smokes out the neighborhood.
(broken link removed to https://www.dec.ny.gov/chemical/81268.html)

What conditions constitute a nuisance under Part 247?


Examples of nuisance conditions include:

• Activating smoke detectors in neighboring structures;
• Impairing visibility on a public highway; or
• Causing a visible plume migrating from an OWB and contacting a building on an adjacent property.

The above list is non-exhaustive and other conditions may also constitute a nuisance.
What penalties could be imposed if it is determined that my operation of an OWB created a nuisance condition?

If found to have created a nuisance condition, the DEC will try to work with the OWB owner to address the nuisance. The owner may need to take measures to eliminate the nuisance, such as increasing the height of the stack or by implementing good burn practices. In some case, the owner may be required to replace the OWB with a newer certified model or a different type of furnace. In addition, the operation of an OWB resulting in a nuisance condition under Part 247.3 is a violation, which may result in the imposition of civil penalties, fines, and/or imprisonment under Article 71 of the Environmental Conservation Law.

IMHO if you live on a rural lot with significant acreage and no nearby neighbors feel free to impact you and your families health by installing one but if you have neighbors within a 1000 feet then I would seriously remove an OWB from your options. The only way to run one clean is put in storage and run batch burns which is effectively an Indoor gasifier boiler configuration with storage. If you want to put an indoor gasifier with storage in an outside shed thats fine. There is a fundamental problem with an OWB no matter if its EPA certified that wood only burns efficiently within a range of boiler output. Once an OWB has met the heat demand for the house it has to idle until the next time there is heat demand. During this period of time the boiler is idling and thats going to put out a lot of unburnt gases and CO into the neighborhood.

I also suspect that many dealers and owners just fundamentally ignore the operating manuals and burn green unseasoned wood. I have been at shows where the salesman are advocating that there is no need to season or split and many owners I have talked to over the years boast that they save a lot of time as they dont need to split the wood. In many of the OWB installs I have seen and owners I have talked the majority are burning bulk green wood. At best the wood gets cut to length, stacked for a few months and thrown in the boiler. Sure it will burn but the inevitable vapor plume is indicating that the majority of the heat is going up the stack and they are using far more wood. An EPA certification does nothing to reduce this lost heat due to moisture content and I expect many units are kept in bypass so they will burn. I also see folks installing larger than needed models so that they only have to feed it once a day. That is another invitation for idling the boiler.

I am biased as I had to go back and forth with local code folks when a neighbor did an illegal install of an OWB. My attic smoke detectors were going off on occasion and especially in shoulder season my entire lot smelled like smoundering wood many days. He ended up having to put in a 30 foot stack and a pole to support it to makes things tolerable and after a few years of skunking out his own yard during shoulder seasons he just uses it during really cold conditions where the boiler does not idle as often. The install still does not meet state standards and I have been advised that I could successfully sue to have it taken out of service if he contined to run it in shoulder season. In order to make it legal the stack would have to be at minimum of 30 feet higher due to topography.

 

[Medic21]

While you are making the choice, keep this in mind, OWBs are restricted or banned in parts of the country as they can become a nuisance to the neighborhood. New York has special regulations in place that homeowners are required to comply with and any one installing and operating an OWB are opening themselves up for future liability when the boiler inevitably smokes out the neighborhood.
(broken link removed to https://www.dec.ny.gov/chemical/81268.html)

What conditions constitute a nuisance under Part 247?


Examples of nuisance conditions include:

• Activating smoke detectors in neighboring structures;
• Impairing visibility on a public highway; or
• Causing a visible plume migrating from an OWB and contacting a building on an adjacent property.

The above list is non-exhaustive and other conditions may also constitute a nuisance.
What penalties could be imposed if it is determined that my operation of an OWB created a nuisance condition?

If found to have created a nuisance condition, the DEC will try to work with the OWB owner to address the nuisance. The owner may need to take measures to eliminate the nuisance, such as increasing the height of the stack or by implementing good burn practices. In some case, the owner may be required to replace the OWB with a newer certified model or a different type of furnace. In addition, the operation of an OWB resulting in a nuisance condition under Part 247.3 is a violation, which may result in the imposition of civil penalties, fines, and/or imprisonment under Article 71 of the Environmental Conservation Law.

IMHO if you live on a rural lot with significant acreage and no nearby neighbors feel free to impact you and your families health by installing one but if you have neighbors within a 1000 feet then I would seriously remove an OWB from your options. The only way to run one clean is put in storage and run batch burns which is effectively an Indoor gasifier boiler configuration with storage. If you want to put an indoor gasifier with storage in an outside shed thats fine. There is a fundamental problem with an OWB no matter if its EPA certified that wood only burns efficiently within a range of boiler output. Once an OWB has met the heat demand for the house it has to idle until the next time there is heat demand. During this period of time the boiler is idling and thats going to put out a lot of unburnt gases and CO into the neighborhood.

I also suspect that many dealers and owners just fundamentally ignore the operating manuals and burn green unseasoned wood. I have been at shows where the salesman are advocating that there is no need to season or split and many owners I have talked to over the years boast that they save a lot of time as they dont need to split the wood. In many of the OWB installs I have seen and owners I have talked the majority are burning bulk green wood. At best the wood gets cut to length, stacked for a few months and thrown in the boiler. Sure it will burn but the inevitable vapor plume is indicating that the majority of the heat is going up the stack and they are using far more wood. An EPA certification does nothing to reduce this lost heat due to moisture content and I expect many units are kept in bypass so they will burn. I also see folks installing larger than needed models so that they only have to feed it once a day. That is another invitation for idling the boiler.

I am biased as I had to go back and forth with local code folks when a neighbor did an illegal install of an OWB. My attic smoke detectors were going off on occasion and especially in shoulder season my entire lot smelled like smoundering wood many days. He ended up having to put in a 30 foot stack and a pole to support it to makes things tolerable and after a few years of skunking out his own yard during shoulder seasons he just uses it during really cold conditions where the boiler does not idle as often. The install still does not meet state standards and I have been advised that I could successfully sue to have it taken out of service if he contined to run it in shoulder season. In order to make it legal the stack would have to be at minimum of 30 feet higher due to topography.

a gassifier will not have this problem and is epa certified. That’s the difference.

 

[maple1]

Something else to consider is all IWBs are not equal either.

I would not install an IWB, in my basement/house, that was forced draft. It would need to be induced draft.

 

[NorthernNY]

Something else to consider is all IWBs are not equal either.

I would not install an IWB, in my basement/house, that was forced draft. It would need to be induced draft.

Maple can you tell me why you are against forced draft in the basement of the house vs induced??? What models do you know of that are forced draft??

 

[NorthernNY]

Econoburn makes an outdoor unit.It is basically the same as the indoor unit with more insulation and a metal shed around it.
I have one which ironically ended up as an indoor unit.I didnt know how long it would take to get my boiler building finished,it was in stock and i got a good deal.
I personally would never have a fire burning appliance in my home,there is no Fire Department where i live,so having the flame sources out of my house is my fire insurance.
I have no problem going outside at -40C to go to stoke the fire.It needs to be filled after 3 hour burn,so not a big deal to go outside.All the mess and danger is seperat from my home which is worth the walk.Plus i have a warm workshop 24/7 all winter long to work in.No mess in my home from dirty chainsaws,stinky snowmachines,dusty wood working ect.Plus the fact i never have to worry about carbon monoxide poisoning is worth every cold and miserable walk if there are any.

Im leaning pretty heavily towards an indoor model right now but since Econoburn has indoor models that like you said are virtually the same, what has your experience with Econoburn been?? Ease of cleaning and service? Self install?? Any problems or wrinkles that you have had??

 

[maple1]

Maple can you tell me why you are against forced draft in the basement of the house vs induced??? What models do you know of that are forced draft??

They have a tendency to spill smoke when you open the door. So dirtier that way. Not so bad in an outbuilding, maybe, but not so good for a basement.

Looking back the thread & ones mentioned, I think the Econoburn is forced. Not sure about Heatmaster. Think Tarm & Attack are induced. Check literature on any you are looking at, should be able to tell - I am not 100% sure.

 

[salecker]

Im leaning pretty heavily towards an indoor model right now but since Econoburn has indoor models that like you said are virtually the same, what has your experience with Econoburn been?? Ease of cleaning and service? Self install?? Any problems or wrinkles that you have had??

I am in the middle of nowhere. Service from Econoburn has been great whenever i need a part or information. I have only replaced my nozzle once,and i probably did it to soon. Seeing the nozzle is a essentially a chunk of concrete i got castable refractory and stainless steel needles and plan on casting my own to save the freight on a chunk of concrete from New York.
My original control board went,that wasn't unexpected and the updated control board seems to have solved that issue.At the time i was able to run the boiler with an extension cord and using one of my aqua stats as the high limit.Having storage allowed for this temperary use without any issues.
I can clean my flue tubes in about an hour now with tools that i have made.
And i did my own install with 1000 gals of storage.
Other than the smoke staining on the outside of the boiler you would not know it going into its 10 or 11th season.
I would buy one again.

 

[Medic21]

They have a tendency to spill smoke when you open the door. So dirtier that way. Not so bad in an outbuilding, maybe, but not so good for a basement.

Looking back the thread & ones mentioned, I think the Econoburn is forced. Not sure about Heatmaster. Think Tarm & Attack are induced. Check literature on any you are looking at, should be able to tell - I am not 100% sure.

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

 

[3fordasho]

Maple can you tell me why you are against forced draft in the basement of the house vs induced??? What models do you know of that are forced draft??

Generally for indoor gassers a forced draft unit will have the blower on or in the front door and Maple is correct there are more issues with smoke spillage when reloading. (blower is pushing air into firebox vs induced which is pulling air through and the blower will be located near the flue exit) My Attack, and I believe Froling, Varm, and effecta are all examples of induced draft. My experience with the Attack is there is very little smoke spillage and I could live with it in my house.

 

[Bad LP]

My Tarm will spill a little when I operate it outside the instructions. I’ve learned to minimize it but letting it burn down to coals per instructions is best.
I’ve been out of the house for 5 days and my tanks were at 80. Useless for heating but damn... it was the easiest fire I’ve ever started from install. Normally I’m down to low 60’s or high 50’s.