Outdoor boiler comments and Q&A archive

A satisfied ex-outdoor boiler owner

About eight months ago I contacted you about wood gasifiction boilers. I had bought an outdoor furnace the previous year and was very dissatisfied by it's performance. I had after one season decided to find a better way or install propane in my house. I searched long and hard and found only three options: Tarm, Blue Flame and AHS. After seeing both the Tarm and AHS (alternate heating systems), I chose the AHS since the Blue Flame was not available in this country, and the Tarm needed the wood to be cut pretty short.

As you said they were not gasifiction boilers but downdraft boilers. I now am pleased with heating with wood again. It is amazing after having an outdoor boiler how much wood wafted away as smoke. I compared 7 day usage between last year and this year during cold snaps both averaging 25°F during the day and 9°F at night. I used one full cord of white oak for the outdoor furnace and 1/3 cord for the new unit and smoke has never been a problem compared to the smokescreen I used to have

I just want to thank you for your quick response to my questions on this subject and am grateful help such as you exist.

Yours Truly,
Jerome

I am smoking out my neighbors

I wish I would have read your site before investing in an outdoor wood furnace. I did not realize how smoky they would be and harmful to my neighbor (even 300 ft away). I am smoking them out. Essentially, I can no longer operate the furnace so I would like to know the alternatives. In one of the articles, someone mentioned oil and propane central boiler. I was hoping that I could replace the wood furnace with an outdoor propane or oil central boiler (using existing pipes, etc...)

Any suggestions where I could look for a propane or oil-fired central boiler would be greatly appreciated.

Thank you.
Luc.

Luc,

We are sorry to learn of your big smoke problem. You are doing the right thing to not use it anymore.

We do not know of any outdoor oil or propane furnaces, but this would be the sort of thing you could look into locally. I would think that it wouldn't be too hard to install an oil or propane sealed combustion furnace in your house and save you some money due to the increased efficiency compared to outdoors.

Good luck.
Cal

My outdoor boiler works fine

I think that the majority of people that are satisfied with their outdoor boilers have stainless boilers, live in a rural setting, have always heated with wood, and have a good supply of fuel.  I am heating two buildings and my domestic hot water with my boiler which is located 350 feet from my home and 75 feet from my shop. My house insurance went down by $150/year by eliminating my indoor wood heater.

Yes they smoke more than a high efficiency wood heater, however, if stoked twice a day with well seasoned wood my visible smoke output is very low.  My old furnace smoked steady while my boiler smokes for about 10 minutes before getting up to a cleaner burning temperature.

For me it is about convenience, I can get 30 hours of burn time when it is -25c outside. I agree that manufacturers tend to be on the 'optimistic' side when giving burn times. In their defense, there are a lot of variables going in to burn times and they are after all trying to sell their product.  They are not the first or last manufacturer of a product to stretch the truth to sell their wares.

It would be nice if we could just agree that wood is a great way to heat, and that some methods of combustion are more efficient than others. Outdoor boilers have their place and that is in a rural setting. My wood consumption is not out of line with what it was before and it is inexpensive and readily available where I live. I am very happy with my Outdoor boiler.

Paul

Hi Paul,

I think you are probably right that under the conditions you mention most OB users would be satisfied.  But many are not satisfied, which is why we have such an active dialogue about them.  Plus, there must now be hundreds of local jurisdictions that have banned them after someone with poor judgment installs one near neighbors.  We don't think that 50% efficiency and 50 grams per hour of smoke is acceptable performance in this day and age when better technologies clearly exist.  That is why we promote emissions regulations for OB of the sort that have transformed wood stove technology in the past dozen years.

John

Common sense versus technical knowledge in boiler design

I haven't read everything on your site about this topic so may have missed this suggestion:  what would be the expected smoke problem from an outdoor boiler if it was used to heat water in a large storage tank, and the stored heat then extracted over several days while the boiler was off and cold?  This would allow the boiler to be run hot and (relatively) clean, reducing if not eliminating the smoke problem.

I have considered building one of these myself for a Panabode house I'm putting on a 5-acre property I'm moving to in the next few months;  the shop is under construction right now.  I build pottery kilns and assay furnaces for a living and therefore am competent working with firebrick making chambers that stay at over 2000F for months at a time for many years;  destruction of these occurs from corrosion of the 70% alumina firebrick, not from heat.  So would I be able to build a firebrick combustion chamber with the exhaust gasses passing through a conventional many-tubes-in-a-tank heat exchanger and achieve a clean-burning system?

I've learned over the years of burning with wood that efficiency is simpler to achieve than it would appear at first glance:  buy top quality, keep it smaller and burn it hotter, rather than bigger and cooler.  It took me 3 stoves to find that out, finally falling in love with a Petit Godin, which is what will go into the panabode.  I bought mine (1979) just before the requirement for CSA testing so it is not labeled, but I have subsequently found that the model I have (3720) was tested and certified and I have obtained the CSA file for it, so am hoping that the inspector sees the world the way I do!  We'll see shortly.

This looks like an excellent website, especially to someone who can grow enough wood on his 5 acres to keep himself warm for the foreseeable future, gas prices notwithstanding.  It will be fun watching the popularity increase again like it did in the mid-70's, and listen to all the old ideas being re-discovered.  I grew up on a farm where wood was the only heat we had, and have always wondered what all the fuss was about!  There's a lot more common sense to it than rocket science.

Len

Hi Len,

I agree with much of what you say, but I'm not so sure about your take on common sense and wood burning.  I've seen too many fire hazards caused by the application of 'common sense' by the homeowner during the installation of a wood stove and/or chimney.  And I suspect that the stove manufacturers who collectively spent many millions of dollars back in the late 1980s developing combustion technologies to meet the EPA emissions limits would not agree that low emission, high efficiency wood burning technology development is just common sense.  Over the years I've taken the view that common sense is highly overrated in the field of wood burning.

However, I do agree wholeheartedly with your assessment of outdoor boiler technology.  Yes, burning at high rate and storing the heat is one way to reduce emissions.  The big mistake made by virtually all outdoor boiler manufacturers is to surround the primary combustion chamber with a heat exchanger in the form of a water jacket.  I think it is amateur 'common sense' to focus on heat transfer as the key to efficiency, when experienced combustion engineers know that good quality combustion must come first and is the big challenge, and after that heat transfer is easy.

What I read in your message does not sound like common sense as much as a depth of technical knowledge about combustion and heat transfer.  And I think you are right.

In answer to your question about boiler design, yes an insulated primary combustion chamber and multi-tube heat exchanger is the right general design.  But there is a whole lot more to it than that which is why we don't recommend that anyone build their own systems.

John

Which outdoor boiler is the best buy?

Hello, Trying to decide on which outdoor wood furnace is the best to buy. Any suggestions?

Shirley

Hi Shirley,

If we could find one that burned wood without smoke, we would probably recommend it. But we can't. See our discussion of outdoor boilers.

John

I've got a broken outdoor boiler

I found your article very interesting, as well as the feedback from others. I recently purchased a house in a rural setting which has an outdoor boiler system installed, with a backup forced air electric furnace. The unit was purchased from *******, who no longer seem to be in business. Just before we purchased the property (last Dec), the owner indicated the boiler developed a leak in the firebox, so he shutdown and drained the system. I ended up using the electric furnace last winter. We have a wood stove in the unfinished basement and an old Empire wood stove in the kitchen. Neither seemed very effective as a primary heat source. My plan was to see if the leak in the boiler could be repaired, or if not, the cost to replace the unit. Can you provide any reputable contacts for these options. Based on your article, I'm wondering if I might be better to replace my furnace with a wood burning/electric combo furnace. Any comments on how efficient these units are? Any help would be appreciated.

Bob

Hi Bob,

The right wood heating system depends on the house size and design and your objectives. I don't have enough information to recommend a particular approach.

We have no basis for advising people as to the best outdoor boiler to buy. We know of no outdoor boiler manufacturer or retailer who does not seriously distort the truth in order to sell the product. Too many people have been mislead and wasted money on outdoor boilers for us to have any confidence making recommendations. The failure by leakage of your boiler is fairly widespread so we hear. Fixing it is probably not a good strategy; I think there is a serious design error (beyond the obvious design errors that plague all outdoor boilers).

Generally speaking, we promote space heating using advanced wood stoves or fireplaces because they are certified as clean burning by EPA, produce higher net efficiencies and burn less wood. It is worth noting that about 80 percent of Canadians who heat with wood do so with wood stoves.

On the other hand, furnaces and boilers are not emissions certified and tend to burn dirtier and at lower efficiencies than stoves.

I think you need to go to a reputable, experienced wood stove retailer and get some advice based on your house size and layout and your objectives. Before you do that, you might check out NRCan's online wood heat book. It has lots of product category information and general advice on selection and installation planning criteria.

John  

Oh, No! I just bought an outside wood boiler

Oh, No! I just purchased a[n outdoor boiler]. Now I find your site on the web. I just got this computer and learning how to use it.

Any suggestions? Sell it? I don't feel too good now. Your site is excellent. Wish I had seen it earlier.

John

Hi John

I too am sorry you didn't find our site before buying an outdoor boiler. It might not have changed your decision, but at least you would have had more information to work with. We have had a fair amount of traffic on the site and through email on outdoor boilers recently. We have added a page of dialogue with our visitors about them. 

You might find Barney's comments useful. He claims that through careful operation, smoke can be minimized, although he admits it still smokes. We also report on an EPA study of outdoor boilers about half way down the outdoor boiler article and provide a link to it in pdf format.

John

Another problem with outside boilers

I recently read of a vacation home in the mountains of Central Oregon whose original builders had been persuaded to install an external boiler heating system. They had to replace frozen pipes numerous times, and it seems an obvious point that an outside boiler is not a good choice for a house that is not continuously-occupied, though apparently there were freezing problems even when the system was fired up. Admittedly, some of the freezing problems might have been due to improper installation of pipes, rather than design of the outside boiler.

The second owners of the property suffered through one winter, when in addition to freezing problems, they discovered the boiler had a voracious appetite for fuel, making it very expensive to operate. In the end, they decided to replace the boiler system with a propane furnace, supplemented by a modern indoor wood heating stove. Propane is normally not an economical fuel, but in this instance they found it cost less than the firewood to keep the boiler going, and at considerably less trouble.

This single example can of course not be taken as proof that outside boilers don't work; however, it IS a good illustration of how they are a bad choice in certain situations, and how someone apparently received very bad advice about them in the first place.

Roger

Hello Roger,

Thanks for the note. That is a sad outdoor boiler story. We have heard all those complaints but maybe not in a single example like that. One of woodheat's main jobs is to help people to be successful with wood burning, and we have been hearing of problems with outdoor boilers for years, which is why we take a cautious and even critical approach to the technology.

Mind you, for every dozen problems we hear about outdoor boilers, we hear of other people who are satisfied with the performance of theirs. Although the combustion design of almost every outdoor boiler I've seen is either crude or non-existent, another serious problem is poor system sizing advice from part-time retailers. A properly-sized system might work reasonably well in the hands of an experienced operator.

Thanks again for the note.

John

A readers analysis of wood boilers

Hi: I am interested in a wood boiler but I am not satisfied with the technology that is available in Canada. Many of the people I talk to who have outdoor boilers all have the same complaints. The complaints being wood consumption, smoke, cracked boilers, leaks, what do you do when you want to go away, what if you want to sell your house?

There are many European manufacturers such as HS Tarm, Mescoli, Perge, Kuenzel etc. that claim to make efficient wood boilers. I am not interested in an outdoor boiler as much as one that I would install in my garage that is attached to my house. My question is are there any manufacturers in Canada that make a high quality unit that makes use of wood gasification technology and are a multi fuel unit? All of the manufacturers recommend that you also install a heat storage system that reduces the amount of time that the boiler is idle. I think that this idea would help to correct some of the smoke problems that many people are experiencing. What do you think?

I personally think that the Europeans are on the right track. What do you think about the technology that they are currently using? 

I read an article that talked about a manufacturer in Parrsboro Nova Scotia that makes a unit that uses this technology are they still in business? Have you heard of them?

I thoroughly enjoy your web sight keep up the good work.

Sincerely, Tim

Hi Tim,

You're completely correct in your entire analysis of the current boiler situation. The only high efficiency boiler I am aware of in North America was the Kerr Tempest from Nova Scotia.  I haven't heard from them in years and I'm not sure if they still make it. The Tempest is the "old" Jetstream technology as developed by Professor Hill from the Audubon society. It uses heat storage technology but is very modest in size.

Cal

Research into outdoor boiler pollution?

Enjoyed your article on outdoor wood furnaces. I live near one of the outdoor wood furnace's and at times it's very smoky. The problem I see is that the flue is at ground level and the smoke stays at ground level.  I'm very concerned if another outdoor furnace were to be added to the subdivision that there would be a very serious health issue plus the value of my property would decrease. Do you know of any research going on to correct this serious low level air pollution?  
Yours Truly  
George  

Hi George,
As you can tell from the tone of our article on the subject, the smoke pollution from outdoor boilers is a serious concern to us and your note is representative of several we have received.  We don't think that the smoke production is inherent with this product category or is contributed to by their short stacks.  Instead, it is our assessment that the smoke is largely the result of bad design.  The boilers we have inspected all combine the primary combustion chamber with the heat exchanger; that is, the firebox is surrounded by a water jacket.  From a combustion efficiency point of view this is just about the worst possible design.  

In answer to your question, no, we are not aware of any research going on to correct this problem.  However, the CSA committee responsible for standard B415 on emissions testing and rating of woodburning systems recently approved for publication a new edition that, if adopted into federal or provincial legislation, would require outdoor boilers to comply with an emission limit of 7.5 grams of smoke per hour of operation or 0.137 grams per megajoule of heat output, whichever is the greater. For context, that emission rate would mean the exhaust would be invisible for most of the operating cycle; in other words, a big improvement over current technology.  

Late last year the Council of Canadian Ministers of Environment agreed to the establishment of an emission regulation for woodburning devices, presumably based on the requirements of CSA B415.  Although we and other stakeholders are being kept in the dark about current status and future implementation plans, at the present rate of activity it will probably be several years before new outdoor boilers would be required to meet emission limits, and of course, this low-cost government initiative would have no effect at all on existing equipment.  

We think that smoke emissions from existing outdoor boilers can be reduced through the use of seasoned, properly processed wood fuel and by helping users to change their operating procedures to reduce smoldering, but the reductions achievable using these methods would have to be confirmed by field testing before they could be actively promoted.  However, in Canada these days there is very little apparent interest by government in supporting research to investigate the means by which the emissions of existing equipment can be reduced.  We have made various suggestions but are told there are no resources to support such work.  We have been most disappointed in our recent contacts with government on this and related issues and have no reason for optimism that the situation will improve any time soon.  

I hope you don't mind that I have copied this correspondence to representatives of the federal and your provincial government with responsibilities in this area, as well as non-governmental colleagues with an interest.  I would suggest that you contact your provincial environment ministry and ask them for help. 
http://www.gov.ns.ca/envi/ 
I should point out, though, that other correspondents who have sought help from their provincial governments received either none or an inadequate response. But, only if people like you bring the problem to government's attention will there ever be the possibility of support.  

If the owner of the outdoor boiler near you is not hostile to a discussion, you could suggest they get in touch with us for some advice.  Sorry that I couldn't be of more assistance.  Best of luck.  
John 

Controlling outdoor boilers through municipal by-laws

Hi John,

We were in contact last week on a discussion about an outdoor furnace. It is now 4:05 AM May 31 and the smell from the outdoor furnace near me so bad it's all through my house. I feel very strongly that if these very smoky furnace's are allowed in subdivisions or built up areas than there will be serious health problems. We are trying to get our local Municipality to pass a bylaw that would restrict them to a minimum of 125 feet from a property line, which is no easy task. People cannot appreciate the smoke they produce unless they were to live near one. The 125 feet would eliminate them in subdivisions. The one neighbor next to the outdoor furnace has it setting 10 feet from his property line and 90 feet from his house. They get the smoke so bad their house smells like creosote on the inside. They have complained to the owner of the furnace to no avail

I had the opportunity to view an outdoor furnace 28/5/00 and was very surprised to find the only stamping was a Made in Canada tag. It was not firing at the time of viewing so I opened the door and all I saw was a buildup of creosote.

Can you help in any way such has pointing me to a municipality or town that has restricted the installation of these outdoor furnaces, someone that may have good information, etc..

I took my situation to the Nova Scotia Department of Environment but without standards it's very difficult. I am getting some information from their Environmental Engineer but that's going to be slow and the standards are going to be awhile in coming.

I want to make it very clear that I'm not against burning wood but I am for responsible burning to protect the environment and our health. As I write this note my nose is burning and I've gotten a headache from the smell.

Thanks in advance , George  

Hi George,

Sorry to hear that outdoor boiler smoke is making your life miserable. Here is a list of Ontario municipalities that have established bylaws to control outdoor boiler smoke, mostly by either banning them from the town limits or requiring property line clearances as you suggest. I was given the list by an Ontario public servant and have no details except the jurisdiction and date the bylaw as enacted. I am aware that this is not a complete list.

• Town of Keewatin; May 1993

• Town of Jaffray Melick

• Town of Dryden; September 1993

• Town of Fort Francis

• Town of Kenora; October 1993

• Township of Machin; April 1994

• Town of Sioux Lookout; January 1998 (previous bylaw repealed)

• Township of Atikokan; September 1994

• Township of Ignace; September 1993

Also, from another contact with a person in Bancroft, Ont. faced with your situation, I spoke with the town's bylaw enforcement officer and he sent me the bylaw. The bylaw, enacted in March 1995, restricts outdoor boilers to lots having a rural land use zoning designation and restricts location to 100 metres from a residential lot line and 60 metres from any other lot line. Unfortunately for the victim who contacted me, the bylaw is not retroactive, so the boiler that plagues him is still there smoking. Let me know if you want me to fax the bylaw and contact information to you.

If there was any interest, I would be willing to host an email discussion group to serve as a clearing house for information and hopefully some solutions to the outdoor boiler smoke problem. We could invite some boiler manufacturers to take part and maybe advise on what they think are best practices. Do you think there would be any interest in an email discussion from the people you are dealing with? I have copied some other people on this message and maybe they have comments or interest.

John

Outdoor boilers downtown?

I am researching a project. My question is: is it recommended that outdoor boilers be used in urban areas on relatively small tracts of land even if  the boilers are installed properly?  I'm concerned more with environmental factors, as well as their use in  residential areas.  Any information about outdoor boiler use would be greatly appreciated.  

Thank You.    
Jeff 

Jeff,
I guess it depends on who does the recommending.  If you were to ask the bylaw enforcement officers of the many jurisdictions that have banned outdoor boilers because of smoke complaints, the answer would be an emphatic NO!  As far as we can tell, correct installation does not resolve the smoke problems because it is the system characteristics of most outdoor boilers that causes the smoke, not specifics of the installation.  

Regards, 
John