Wood Furnaces

jwade55_3

Great people to work with, Tom is a great guy. Indoor Wood and coal fired unit.

http://www.marathonheaterco.com/

J

Josh_10

Recently we had an opportunity to work on a wood fired furnace/boiler. I really like the idea! We are on the lookout for a product that we can become a dealer for. Does anyone know of a really great manufacturer that we might petition?

Thanks,

Josh
Mitchell Mechanical, Inc.

Leo

a Heat exchanger

Find one that advocates using a heat excahnger if it is open to the atmosphere or you void boiler warranties.

Leo

Unknown

these seem pretty skokum

a friend of mine has one of these in his place and loves it:

thermo 2000

Eric Johnson

Marathon a great boiler

I second the endorsement of Marathon. I heated a big old house in the Adirondacks with Marathon indoor boiler for 10 years (gravity feed system) and loved it.

But they don't make an outdoor unit.

Now I have an old Royall indoor boiler that I really like now, heating a much bigger house. Royall (Horstman Industries). They make a nice outdoor model as well. All their boilers have the ASME stamp.

http://www.royallfurnace.com

Heatmor is another good brand, as is Central Boiler.

Josh_10

That's interesting.. Why not heat exchangers? You can't use it with anything that is higher than the boiler if it is vented! This is a pretty new concept for me. What is their reasoning?

Leo

Heat Exchangers

In our area there is a guy selling them and saying you don't need a heat exchanger just pipe them into your present boiler. These are non pressure boilers and open to the atmosphere. The problem is the fresh oxygen will ruin your present boiler and void the warranty, a heat exchanger will eliminate this potential problem.

Leo

Josh_10

Not to mention the water column pressure if the house is more than one story.

Tom_35

Greenwood furnace--

Go to www.greenwoodfurnace.com. This is a first class boiler that can be installed inside or outside. Their website is really good and gives lots of good info.

Call Michael Kuehner on their toll-free number.

Tom Atchley

S Ebels

I would wait

I have a feeling that there is a big shakeout coming in the solid fuel industry, especially in the realm of outdoor wood burning equipment. The state and federal powers that be are going to get into the regulating game on those things due to horrible efficiency and emmisions that make a 9 spot smoking oil furnace look clean by comparison.

From what I have heard, there are a bunch of different brands being tested right now under lab conditions to determine actual efficiency and pollution. The results are supposed to become public in mid April. Sit tight unless you're looking at something with a gasification type burn ala Tarm or Garn. There's not much else that will hit the mark.

[Deleted User]

Scary thought...

a pressure relief valve terminating in the combustion chamber...

Why do I get the feeling this appliance will never get an ASME approval as currently configured?

I can see the scenario now. Recently filled combustion chamber, full blaze, power failure, steam, pressure relief valve pops off, WHOOOMPF, ashes EVERYWHERE...

Pretty scary to me.

ME

hr

I prefer pressurized

only a handful that I know have any listings, however. Royall has ASME and UL. Most of the import gasification units have TUV.

Some claim to have UL but it may only be on a component or two, not the entire assembly.

I agree they need to clean up emissions especially considering the recent popularity.

Gasification or back to some sort of catalyic converter device.

Always check with the owners insurance before suggesting indoor wood burners. Some do not allow them at all others add an additional premium.

Prescreen the customer carefully there is a bit of work to fire, maintain, and clean them.

Connecting them to an exisiting system can take a bit of piping to do it correctly. Bid the install carefully.

hot rod

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ChasMan

Yeah but it has a cute animal on the front so it must be ok.

ChasMan

One can only hope.

Eric Johnson_3

hot rod is absolutely right--heating with wood is a huge commitment.

I have a catalytic combustor hooked up to my Royall. It's an add-on so it's not as slick as the ones that come designed into wood stoves, but it does cut the smoke and increases efficiency somewhat.

I second the notion that a Tarm or Garn gassification boiler is the way to go if you're in a populated area and want an indoor, pressurized boiler. They're not cheap and they require some monkeying around to work right, but what else is new? I know that Tarm recommends a water storage tank, which makes sense but is also expensive.

If you decide to buy a non-pressurized outdoor unit, make sure the firebox is stainless steel. You can get boiler plate models, but if your water treatment chemicals fail, you're going to be looking for a new boiler in a couple of years. I find it interesting that Royall makes both pressurized and non-pressurized outdoor boilers. Something for everyone.

Joe D.

Wood system

I heat my house and garage with hot water heated by a wood fired boiler. An old Kewaunee unit I rebuilt. It sets away from the house. Right now it feeds a manifold in the basement. It is used in conjunction with a Burnham gas fired unit setting here in the house.

They both feed the same manifold which the baseboards are plumbed off of. When I use gas, I shut the valve from the wood unit off at the manifold, and the valve from the gas unit when it is not in use. But, the water used is common, I don't use a heat exchanger.

This outside unit, all carbon steel construction, used to be open to the atmosphere, with the resulting corrosion and leaks in the flues. There was a 4" threaded hole in the top of the boiler which I kept loosely covered to avoid pressure buildup.

My oxygen intrusion remedy was to take a 4" pipe plug and bore a 2" hole through it in the lathe, cut the filler neck out of an old automobile radiator, braze it to the pipe plug, put it all back on top of the boiler in the threaded hole, and install a anti-vacuum 7 pound radiator cap on the filler neck. Now, It is a low pressure water heater.

On this type of boiler setup, if and when I let the fire go out, when the water cools off and shrinks in volume, it created a vacuum, and a typical radiator cap will allow the vacuum to suck in air/oxygen from the atmosphere and ruin everything. These anti-vacuum caps prohibit this from happening. On another fitting on the top of the boiler, I had installed a 5" diameter combination vacuum-pressure gauge on a pigtail. When it's making heat, the boiler carries about 4 psi. When the fire is out and the boiler is cold, the gauge drops to about 1 or 2 on the vacuum side.

A good stainless steel brand of wood heater is the Hardy outside wood heater. You can google them and look them up. They are common in this part of the country. All SS construction, open to the atmosphere. Forced draft. High dollar, though.

Mike T., Swampeast MO

Guy at local county fair selling an outdoor wood boiler (can't remember brand) tried to tell me that it was 95% efficient! Also said that "one size fit all" from modest house to "that arena building over there"! VERY primitive looking inside--rather like an old steam locomotive engine. Believe it needs some serious testing of those claims...

hr

Be very careful turning non pressurized

vessels into pressurized ones. A little pressure goes a long ways! Most of those outdoor open systems are fairly light gauge steel and will not handle much, if any pressure. Or vacumn.

If you have ever tried to pressurize a 55 gallon steel barrel you will know what I mean. Even a mere 5 psi makes a barrel look pretty scary

I'd much rather see a HX to isolate the open container from the closed loop system.

Hardy is a big seller in my area also. While they are a very nice looking unit, I'd put them near the bottom of the pack regarding efficiency.

Folks in this area plan on 6-8 cords to heat 2000 square feet with them. I suspect efficiencies below 40%.

I feel 80% is a realistic number for the Tarm and other quality gasification units. I went from a WoodWay to a EKO gasification boiler in my shop and cut wood consumption in half.

I don't feel wood furnace ads are all that believeable regarding efficiencies. I feel they should all be required to have Warnock Hersey or other independent lab efficiency and emissions certification. Too many wild, un proveable claims out there.

hot rod

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Eric Johnson_3

EKO looks nice

I've read the brochures on those, hot rod. Made in Eastern Europe, I believe. I know the Tarm runs around $6,500. I think the Garn is a lot more than that. How much for a comparable EKO?

Josh_10

Thanks for all of your input guys.. I really gained alot from all of your input. I have alot to keep in mind. Here is what I am going to do:

1) I contacted Royall Furnace. We are currently in negotiations. Great product. They have options. They are listed and approved.

2) I will hold home owner classes once a month and require them to pass a simple operators exam before I commission their wood appliance.

3) I have taken everyones advice and will keep it safely tucked in my mind every time I design a system

Thanks again!

Eric Johnson_3

Royall

I like dealing with Royall. For one thing, they're from Wisconsin, and I get out there at least once a year so I can pick up parts at the plant if necessary.

Secondly, I've got an old 6150 that's about 25 or 30 years old and they are still happy to give me technical assistance whenever I ask for it. That's service way, way, after the sale.

Interestingly enough, the current 6150s are basically the same as my old, used one. Same parts.

On efficiency: You guys undoubtedly know a lot more about this than I do, but there's combustion efficiency and heat transfer efficiency. I forget which one the outdoor boiler mfgrs. always cite, but it's the one that favors their product's strengths. Combine the two, and you come up with a much lower number--maybe down around 40% like hot rod said, in some cases.

RadPro

The shakeout is closer than most people think. It has been coming for a long time.
Regards,
Ditchdigger

S Ebels

Efficiency

The testing currently underway is structured to measure how many of the available btu's are actually transfered into the water. The preliminary results I heard about from a person who was there are, shall we say, not very encouraging for nearly every unit tested. Most of the units tested so far have produced air pollution equivalent to just shy of 1,000 oil furnaces. (I'm just using the analogy as it was spoken to me.) That, my friends is a pretty sad number. Couple the pollution with an average efficiency of 30-40%, along with an average life of less than 10 years and I really don't see a good reason to own one. At least not one of the "steel pot with a fire under it" types.

AFA the Garn heater being an indoor unit, yes you can and no you can't. It is UL listed for indoor use but the physical size would preclude EVER getting one into a basement. You can slide one into an outbuilding or something like that but at a weight of 3,000 lbs+..........it ain't goin' in yer basement! The difference between the Garn and the Tarm or EKO is that the Garn comes with the storage tank integral with the unit. The water jacket holds 1,400 gls in the smallest model. This allows complete combustion of the full load of wood all at one time, which is why the Garn is cleaner than anything else.

Unknown

viessmann

had the rep stop by our shop a couple weeks ago and he mentioned that the Viessmann wood boiler is coming back into production! also a pellet boiler as well.

hr

I've heard that Viessmann

is made by EKO Vimar, a Polish manufacture that I deal with. Might explain why they are backed up on orders

The Euros build nice units. My EKO came with outdoor reset built into the control module and a variable speed inducer fan.

hot rod

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hr

I've heard that Viessmann

is made by EKO Vimar, a Polish manufacture that I deal with. Might explain why they are backed up on orders

The Euros build nice units. My EKO came with outdoor reset built into the control module and a variable speed inducer fan.

hot rod

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S Ebels

I've not heard that but

I have heard rumors of a pelletized fuel burner that will bolt on to a Vitola and possibly other power burner models they make. I'll bet we'll know more after the meeting in Waterloo, the 6th of April. There's an open forum section scheduled entitled "When will we......"? Sounds like fun!

Eric Johnson

wood capacity

I've also heard that the Garn doesn't have a very big firebox and takes some trial and error to get it to work right. The firebox capacity becomes an issue if, as you say, it is located in an outbuilding. The only guy I know who has one has it located--you guessed it--in an outbuilding.

Here's a stupid question: Is there a substantial difference between having the water storage around the firebox as opposed to in a separate tank or series of tanks?

S Ebels

Couple things it does for you

I'll be the first to admit that the Garn presents a few issues not present in other wood burners, such as the sheer size of the thing and requiring field insulation. But these are workable problems and ususally don't require any major leaps of materials or knowledge.

As far as your question regarding the btu storage being integral as opposed to remote, I think that all other things being equal, having the storage tank literally surrounding the fire box and HX provides for the best possible heat transfer. If you look at the specs on various brands, you'll see that the Garn has far more heat exchanger area than anything else in that type of product. As the old saying goes, "there's no substitute for sq inches" or something like that. It gives the best possible heat transfer without the hassle of a remote storage tank along with the piping, controls and circulator to make it happen.

Now for the small firebox. Here's a basic rule of combustion that applies to all wood burning equipment. A big or oversized firebox = inefficient and dirty burn. A firebox that is matched more to the amount of btu's you are trying to transfer = clean, efficient and controlable flame. A firebox that will hold way more wood than can be consumed in one continuous burn, does no favors to anyone, least of all, the environment due to ghastly amounts of emmisions if the fire is cycled off/on.

Matching the firebox size to the storage capacity is the key factor in getting maximum efficiency and the lowest pollution out of 100% of your fuel load. If your box is sized in such a way that it requires cycling of the flame during a burn, things go south in a hurry. Tarm also knows this, which is why they heartily recommend massive storage tanks be added to any installation. Hot Rod also has a storage tank grafted onto his system IIRC. The Garn was designed by someone who actually knows and understands the combustion process as opposed to most of the wood boiler places that are just metal fabrication shops.

Here's a simple way to remember all this.

A small tightly controlled, solid fuel fire is always more efficient than a fire in a big oversized box.

BTW, This is an issue that a lot of people don't understand so it was most definitely NOT A STUPID QUESTION

Dave Johnson_2

Efficiency

I agree that the conventional wisdom is that a
small hot fire is the best way to go for pollution control but, I don't think it holds in all cases.
I have a Heatmor outdoor unit. It has a blower and always fires full bore or not at all. There is no way to restrict the air thus, no way to control burn time. The air enters under grates
If I burn a small fire in that big firebox, it burns well but most of the heat stays in the center of the box and the smoke and gases go straight up into the uptake tubes.
If I pack it full of all the wood I can fit in, the pile burns from the bottom up, the smoke and gases wind their way through all that wood on their way out, giving up heat to the top chunks and, because the path is tortuous, there is good air mixing and a longer dwell time. This may even produce some secondary combustion tho I wouldn't swear by it. The only time my unit really smokes is when it is cool and starting up. Once it gets up to temp, the stack is clear. It would seem to me that there should be some way to modulate the inlet damper using the stack temp as a signal. Once you determine what the optimum temp is, you could set the damper to maintain that temp as long as possible. Since I believe I probably operate with 2 or 300 percent excess air, I doubt that this would result in choking back on the air.

hr

the ideal fire size

would be one that matches the fire size to the BTU load being drawn off. That the concept behind the Euros with variable speed fan inducers and outdoor reset control, and a small fire box size that does not allow gross over firing.

The basic "outdoor furnaces" is really not much more than a kettle suspended over a camp fire. Regardless of the fire size they run much hotter flue temperatures which directly translates to the 40- 45% efficiency numbers.

Regardless of how you slice it 60% of your fuel is going up the flue, even if it is burning clear It's a heat transfer game, and the design of the boiler plays a big part. You need to be able to get the heat of the fire to the water.

Gasification process can burn in excess of 1500 degrees yet 350 or so flue temperature. That's a good fire to water conversion.

I guess 30% or lower in the "big smoke" wake up mode.

hot rod

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Solarstar

A wood boiler that smokes most of the day is Not efficient...and a low temperature outdoor wood boiler is not as well Testing /certification in Canada found them to be from 25% to 50 % at best with most being nearer the lower percentile... And the poor neighbor that lives downwind of the thing. Thats why around here they are being nicknamed a Steam Engine ...Paul