Outdoor wood boilers

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is insurance! Not many, if any, insurance companies allow woodburning devices indoors anymore. At least in areas where woodburning is prevelant.

Also, any woodburner, be it indoors or outdoors, needs to have at least a UL listing, and possibly ASME if it is a pressurized boiler. Not many around that fit that requirement. I suspect a large portion of woodburners are installed, after the fact, without the insurance carriers knowledge :) Not many insurance agents do yearly inspections.

These two issues, more than anything, have driven the wood burning hobby, outdoors.

Being a woodburner myself I certainly agree with all the other hassles Martin noted. Indoor burning can be a dirty habit.

Walking outdoors to "firesit" your heat source takes commitment also! The colder the day the longer that walk becomes. Reminds me of my early Montana, outhouse days :)

Mostly $$ cost of fuels available drive HO's to burn wood, or whatever else they can get their hands on that a match will ignite :)

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Richard Snyder

Outdoor wood boilers

In the early 80's, I worked as an engineer with Garn.Inc., a manufacturer of a unique outdoor wood boiler (website www.garn.com) I have kept track of the company since I left and am still convinced that the product we developed then is the best around for long term durability, safety, efficiency and cleanliness of the burn. Most of the units sold when I was working there are still in service with quite satisfied owners.

The Garn units utilize a large storage volume of water (non-pressurized) which allows the combustion to be continuous and not be started and stopped by a thermostat. The result is a high combustion temperature leading to minimal smoke and emissions. After the combustion is finished, effective heat transfer occurs in the piping immersed in the storage water.

I know that there have been many different types of outdoor boilers made since then. I have heard that some of the designs are so smokey that regulations are being developed to manage the situation. The Garn unit will not fill your valley with smoke!

Martin Lunde, PE

Outdoor wood boilers

Since 1991, DECTRA CORPORATION has been manufacturing and marketing the GARN WHS line of wood boilers that Richard discussed in his posting. Many GARN WHS units have been installed since the early 80's and most are still operating. Unlike much of the outdoor wood boiler market, GARN WHS equipment has been independantly tested for efficiency. Additional information can be found at www.garn.com - the downloadable movie is quite informative for those who are not aware of how a GARN WHS boilers operate.

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I applaud the smoke free

high efficiency aspect of your product. All brands should be held to this standard!

I question the validity of storing that much heat in a LARGE water content? Seems when you burn the fuel (wood) you turn a high grade, easy to store energy, into a low grade (hot water)

Now you need to have the energy in the form of hot water, (stored) well insulated and away from any draft induced by the flue pipe. Even the very best indirect tanks (without flue pipes through them) still lose heat to the space. Still seems to me like burning the wood, efficiently, as needed would be the best heat exchange bang. Although we know how challanging it can be to burn a wood fire to the load exactly. Or even closely

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Steve Ebels_3

I agree but..........

What's a viable alternative? Nothing that I know of. To get a smoke free burn you have to establish and maintain a high combustion temp. This is not possible with a wood burner that operates by firing a short time into a small load and then "idling". It makes gobs of smoke,CO and other undesireable junk like wads of creosote.

The only way I see is to burn the wood in the best possible way and capture as many BTU's as you can. Holding them in storage is an additional side of the equation but it can be done efficiently with the right installation.

The "best possible way" is of course a gasification type burn as you know Hot Rod. All the most efficient wood burners like Garn and Tarm use this type of burn.

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As I research and use

some of the Euro gasification units it seems... They have a very small fire box. I suspect, since they locate them inside in Europe, someone "tends" the fire all day. This is perhaps how they keep them burning hot. They also seem to size them closer to the load than the typical US manufactured brands. The brands I mentioned come in sized about 6-10 KW difference, such as 25, 32, 40, 60, and 80 KW versions. It's much better to size close so you are required to burn hot, long cycles. then a 150- 200 gallon storage maybe enough.

My experience shows that owners want to fill them once a day and walk away. Hard to keep an efficient burn going under those conditions. Also many folks want to burn junk, wet, or green wood. This is not acceptable with gasification units. There will be a learning curve for wood burners that switch to high efficiency, clean burning technology.

I have installed Atmos, PK Pyro, and Tarm gasification units to date. In every case the lack of firebox capacity is the biggest complaint. Up sizing the boiler to a higher KW model drives the problem more so, as it tends to cycle them too much.

The new Aquatherm Omega seems to be looking for this fine line with firebox size, water capacity, and clean burn technology.

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Martin Lunde, PE

outdoor wood boilers

Any wood burner that does not have thermal storage cannot match the fire output to the building load at all times. Therefore, such units must have some combustion downtime with its related significant pollution, inefficiency, etc. Thermal storage allows the optimization of combustion, a large fuel load and a perfect match to the building load. I think you will find that most gasification units (including TARM) recommend thermal storage for best operation and efficiency. The GARN WHS product line simplified the whole concept by combing the various components into a single welded unit. Yes there is some standby loss; however, it is insignificant when compared to the losses and pollution produced during the smoldering downtime of a wood burner that is trying to match its burn rate to a low building demand - especially in the spring and fall.

The GARN WHS combustion chamber is sized to allow a 3 to 4 hr optimized high temperature burn for each 24 hrs of heating in most cases (this varies with the calculated heat loss of the building and the particular GARN WHS unit selected). This addresses the problem of frequent fuel loading into a small combustion chamber.

tls_9

Rod?

has your research turned up and manufacturers making a CAST IRON boiler? For indoor use?

thanks

tom

Steve Ebels_3

\"Fill once a day and walk\"

> some of the Euro gasification units it seems...

> They have a very small fire box. I suspect,

> since they locate them inside in Europe, someone

> "tends" the fire all day. This is perhaps how

> they keep them burning hot. They also seem to

> size them closer to the load than the typical US

> manufactured brands. The brands I mentioned come

> in sized about 6-10 KW difference, such as 25,

> 32, 40, 60, and 80 KW versions. It's much better

> to size close so you are required to burn hot,

> long cycles. then a 150- 200 gallon storage

> maybe enough.

>

> My experience shows that owners

> want to fill them once a day and walk away. Hard

> to keep an efficient burn going under those

> conditions. Also many folks want to burn junk,

> wet, or green wood. This is not acceptable with

> gasification units. There will be a learning

> curve for wood burners that switch to high

> efficiency, clean burning technology.

>

> I have

> installed Atmos, PK Pyro, and Tarm gasification

> units to date. In every case the lack of firebox

> capacity is the biggest complaint. Up sizing the

> boiler to a higher KW model drives the problem

> more so, as it tends to cycle them too

> much.

>

> The new Aquatherm Omega seems to be

> looking for this fine line with firebox size,

> water capacity, and clean burn technology.

> hot rod

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_

Steve Ebels_3

\"Fill once a day and walk\"

Isn't that typical of we Americans? Who cares if it smokes like a steam engine and is even less efficient? As long as it's easy, cheap and does the job, people buy it. Many of the OD "boiler" companies use that as a selling point when in reality it's detrimental to efficiency, emmisions and the overall life of the unit.

hr

Cast Iron woodburners?

http://www.newhorizoncorp.com/boilers-fb.html

And you can order a Lamborghini pellet burner for it!

This is the fellow I bought the Atmos and PK's from.

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Martin Lunde, PE

indoor wood boilers

One thing to remember about indoor wood boilers is the need for a fairly tall Class A flue (and the chase thru which it passes) that rises from the basement to a point above the roof. In todays world neither is an inexpensive item and the vertical chase is not always easy to arrange. The use of an existing chimney with a newer wood boiler generally means relining (again not inexpensive). Also, since it is not a direct vent boiler combustion air must be provided - ie generally heated room air.

Other reasons for not going indoor with wood are: dirt, and bugs carried in with the wood; moisture and resultant mold possibilities; ash removal dust; fire hazard with improper installation or operational mistakes; CO and CO2 issues if depressurization of the home occurs; etc. None of these are positive for one's health.