Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: CmBartlett on December 22, 2013, 03:44:31 PM
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I'm a new member to the form and wondering if a could get some opinions on OWBs.
Myself and my neighbor plan on heating two homes (2500 sqft each) plus domestic hot water and a garage (1200 sqft) .
we have the piping installed and hope to get the furnace installed this summer.
we are looking at two furnaces:
1) Portage and Maine, BL 34-44
2) HeatMasterss , Mf 10000e
the stoves seems similar in design with one major difference being the,
Heatmaster is made of 409 stainless steel
Portage and Maine is made of cold rolled carbon steel
not sure which metal or stove would be a better choice, any info would be a great help
thanks
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I spent two years researching and finally went with p&m simply because I like the double welded construction and if I ever do need to repair it, mild steel is much easier to weld. But the whole stainless vs mild steel debate has gone on for years in the boiler industry and I'm sure it will for years to come. It also helps to have a supporting dealer that's willing to guide you. Most boiler mfg. that have been around for awhile don't have a bad product if they did they wouldn't still be in business. I have found in my experience you get what you pay for most of the time so don't cheap out if it's at all possible. Your gonna have to live with the boiler you choose for many many years( hopefully)
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Mr. Bartlett, I don't have an opinion on P&M specifically, other than the price. P&M stoves are at the top of the price list right next to Central. Not saying if that is a good thing or a bad thing, just stating a fact.
That being said, I began looking specifically for a stainless stove. Like Mr. Randy said, the debate rages on and I won't get into that. But, for me, at the end of the debate, I landed on 409.
The rest of my post will be on my opinion of my Heatmaster. And don't take that as an argument OVER P&M. Both are great stoves, I just own a Heatmaster, so that's what I know. I've been running my 10,000E for 2 months now and love it. There are 4 or 5 of us on here with this stove and all have had nothing but fantastic success with them. I think Boydz and Kybaseball are at least 3 years in. The fan blowing below the fire, the shaker grates, the door latch, the smoke routing, the insulation, the thermostat, the damper design, the stainless steel, the ash pan, the finish, are all top notch components that I prefer over other models I have seen. I still find myself looking at other stoves and their designs and end up being so happy with my decision!
If stainless is the side you land on, you won't be disappointed with a Heatmaster. If you land on steel, you will likely be equally impressed with a P&M. Feel free to shoot any specific Heatmaster 10,000 questions my way if you like!
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Id go with the carbon steel stove. Taking on 2 homes plus garages and hot water you will probably have to run the stove at 180 or higher. Most guys I know that run stainless don't go over 170 due to hairline cracking from the higher temps.
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Thanks Victor and Randy, we have tried stainless but with the high firebox temps of the ceramic lined boiler we found that it is difficult to get the anti corrosion of stainless to not crack at the welds, we choose to go hotter and cleaner for efficiency reasons, perhaps heatmaster has mastered that end of things but I think it is to early to tell on either unit to be sure, either would be a good choice in my opinion. Thanks for considering wood as your primary fuel.
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The cracking issues are non existent in a 409 furnace and is simply a story used by other manufacturers to scare customers into buying their product . I assume you could get one to crack if you ran it long enough without water but I've never seen it happen. 304 furnaces may have a issue with it, I really don't know.
The best advice I can give you is to buy from a decent dealer who will assist after the sale. I really know anything about P&M because they don't sell them in my area ( Virginia) or if they do I've never seen them. But I have sold and installed hundreds of Heat Master furnaces. Heat Master is a reputable company that both makes a great product and then stands behind that product.
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Well Yoder first we do sell in Virginia at Huffman trailer sales in Harrisonburg Virginia and have for many years, next I said that WE have had issues with stainless and now choose not to use it, it also has a lower ability to transfer heat to the water, Perhaps Heatmaster has solved the issues that WE ran into, I don't know because I have never seen one local to me here in the Northeast. Again I think either stove is a good choice
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The cracking issues are non existent in a 409 furnace and is simply a story used by other manufacturers to scare customers into buying their product.
First of all, let me say that I'm not a manufacturer of OWB's nor do I sell them. BUT, I am a welder/fabricator of over 30 years with extensive experience in stainless steels, so I know a little about the subject of stainless steels when used in OWB's. I don't think the issues associated with stainless OWB's is 'simply a story used by other manufacturers to scare customers into buying their product', but more a case of someone not fully knowing what they are dealing with in terms of materials and manufacturing processes. It is essential that anyone considering buying an OWB, stainless or otherwise, perform an extensive amount of research in both the history of the company and its' service record as well as how they are putting their units together. A factory tour during production operations should not be discouraged by the manufacturer, nor should answering questions about their processes. When I was looking at different manufacturers I had one tell me they don't allow factory tours. That just sent up a huge red flag for me and eliminated them from my list of prospective suppliers.
Here's a little information that may help you in your search and comparison of OWB's:
At first glance, 409 stainless would seem to be the choice for an application such as an OWB, but many precautions have to be followed in its' manufacture in order to achieve success. ANY stainless fabrication will be prone to cracking and failure at the weld joints if proper welding procedures are not followed. There are a number of welding problems with the ferritic stainless steels, which is what 409 is. Although 409 is not regarded as hardenable, small amounts of martensite can form during welding, resulting in a loss of ductility. In addition, if the steel is heated to a sufficiently high temperature, (such as what might happen with a very slow welding process or repeated welding in one area), very rapid grain growth can occur, also resulting in a loss of ductility and toughness. Although the ferritic steels contain only small amounts of carbon, rapid cooling can 'sensitize' the steel making it susceptible to inter-crystalline corrosion. When this is associated with a weld it is often known as weld decay and is what makes a weld brittle and prone to cracking or outright failure in a heating and cooling application. When I refer to 'heating and cooling', I'm talking about a few hundred degrees of difference, such as what may be seen when a fire in a fire box is sitting at 'idle' and then when the fire is at full flame.
Matching welding consumables, (wire or rod), are available for most grades so that corrosion resistance and mechanical properties can be matched to those of the parent metal. To reduce the risk of hydrogen induced cracking, low hydrogen welding processes are essential and preheat temperatures of 390 to 572°F are recommended. A weld that has been completely transformed to untempered martensite by allowing the joint to cool rapidly to room temperature can be extremely brittle and great care is needed in handling to prevent brittle failure. In addition, such joints are sensitive to stress corrosion cracking even in a normal fabrication shop environment if not handled properly. An alternative is to weld with austenitic stainless steel fillers, type 309 for example, but the weld may then not match the tensile strength of the ferritic steel and this must be recognized in the design of the weld. Nickel based alloys may also be used; alloy 625 for instance, which has a 0.2% proof strength of around 450MPa; and will give a better match on the coefficient of thermal expansion.
Besides the grade of stainless being used in an OWB, the welding process in which it is fabricated would be my biggest concern. I know of one manufacturer that used 409 stainless with disastrous results in each unit they built, while another manufacturer using the same grade of stainless has had more favorable results. I actually ended up buying my OWB from the company that had the disastrous results with the stainless because they recognized their lacking of knowledge in stainless and stopped using it rather than keep experimenting with it, were honest with me about it and allowed me into their shop to witness the whole manufacturing process. They even provided me answers to questions I asked that might not have been in their best interests, but again, they were honest.
I would do a LOT of research in how a boiler is put together before making a purchase you might later regret!
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Chaikwa,
Thanks for your knowledge and insight. Some of the best real info I have read about stainless welding with regard to owb production. Thank you.
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i will skip the metal debate as well as manufacturer. i have a potage/main 250 and so far happy w/ it.
what i worry about is sharing a boiler, maybe it is family i dont know. but as someone posted on this sight before a owf is like that 3rd child that has now come into the family. it takes alot of work to keep it going. getting wood,spliting,stacking,storage, cleaning,maintenace and tending. hopefully wont be a problem w/ i did more than you type issues. whose property is it on, what if you/he moves or runs off w/ the mail lady? also, what about electric bills-whose meter. just be nice to have a plan ahead of time if not in writing. if you cant tell i dont like my neighbor anymore and put up a 14ft fence w/ telephone poles in case he didnt know..
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Thanks for all the great information, definitely pointing me in the right direction for an OWB
keep it coming,
thanks again
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Ditto with Hondaracer, great post Chaikwa
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Well like I said before, I haven't seen any P&M furnaces sold in the area. Never seen them at a show or have never run into them when doing estimates on jobs. So I can't comment on how well they are built or on the reputation they have in the marketplace because I simply don't know.
Most of the comments I have heard on stainless during my years as a dealer were complete lies used by dealers who didn't offer stainless furnaces. One of the comments I often hear is that with mild steel the customer can always weld it back up if there is a corrosion issue. This makes little sense to me because anyone who is a welder knows that welding a crack in stainless is much easier than attempting to weld mild steel that is full of corrosion. Every mild steel furnace that I have ever seen start to leak due to corrosion was not just affected at one point but would continue to give problems at other places after the first was fixed.
My family has sold both over the years and hands down the 409 furnaces have a much better track record. Thats not to say a mild steel furnace will not last many years, its just that after 10 or 20 years I've seen a higher failure rate in them. Then again I haven't sold other brands of 409 furnaces so there may be some out there with issues, I just haven't heard of them. Slim what brands out there have had cracking issues? I would be interested in reading about it.
I have know of brands of 304 that have had cracking issues, I assume many people don't understand the differences between the two.
On the heat transfer issue there are two things that come into play, type of metal and thickness. It is true that stainless transfers slower but mild steel furnaces have to use thicker metal which also slows transfer. The ideal furnace from a heat transfer standpoint would be a mild steel furnace built with the same thickness as a stainless furnace but then it wouldn't last long.
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You know Yoder I'm not saying that stainless is wrong, I personally feel that the industry in the past has gone in the wrong direction as far as heat transfer and firebox design, I believe that as little heat transfer as possible should be from the firebox, that needs to stay as hot as possible, then we should harvest that energy in the heat exchanger itself, we have a great heat exchanger on the 250, could it be better? yes it could . will the general public pay for it? I personally don't think so at this point anyway.
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I completely agree with the design you are speaking of. A very hot firebox gives a clean and more efficient burn. Burn it hot and then capture the heat from the exhaust. I know that is the way Heat Master is headed, I'm really excited about some of the new triple bypass units they have been putting out. Sometime I would love to see a P&M burn and understand the way ya'll do it.
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Please allow me to invite you to my home here in Maine, my adress is 1409 Alfred road Lyman Me, Alfred road is state route 111, just 5 miles off the Maine turnpike exit 32 west, we have lots of room for visitors and my wife is a New York schooled Chef so the groceries are good, stop and say HI
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Sounds fun but I'm not driving all the way to Maine to look at a furnace. But the same to you, if you are ever in Virginia around Roanoke let me know.
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Thats the way all of our gassers are built and there are some major changes in the works for our new stove that wiil make it even hotter. Yoder I know you said that you don't deal up here but we (Brian and I)usually do a couple of shows a year in the Va and Ky area to help those dealers and to spread the word, would you be interested in joining us, we really like to have competition close together and all promoting alternative energy together, our county fair cicuits up here are a big hit with the alt energy crowd because people know where to find us all. For the last 3 years at Fryburg fair myself, Empire and Vigas have dumped over 1 million BTU,s to show our units in operation, there was also Heatmor, Harmon and several pellet stove companies as well as solar and electric alts all together.
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What shows do you do in Va?
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Two years ago we did the logging expo at the Richmond fairgrounds, thats the video that you see of the chip burner on our website believe it or not we sold 2 chip burners from there to a pallet manufacturing facility in Edmunton Alberta Canada, that was a pretty big show to attract from that far away and last year we did the farm expo in Louisville, Ky. I would like to do more but one of the things that I am consistantly told by loggers in the south is that nobody chips the tops of the trees, they just leave them lay in the woods to rot. The liberals up here would hang a guy for that, consiquently there is not much call for the chip burner in your area. As well the competition of less expensive stoves down there is pretty fierce, up here people tend to look more at efficiency rather than just price alone although your heatmasters seem to be opening up a pretty good market in that respect, what ever happened to the guy that was looking to sell for you guys in Massachusetts?
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I have no idea about any dealers north of Maryland. Some of the larger operations here chip on site and everyone else I know hauls pulpwood off to be chipped at a mill. I've never done the Richmond show, we don't have any dealers on that end of the state. Most of our sales are in the mountains on the western part of Va.