Shally from MN, home of Central Boiler and Woodmaster. Glad you could join the discussion. I agree the topic has drifted somewhat but for those considering purchasing an OWB the topic is relevant. You bring up a few good points but they need further clarification. First, the safety listing you're talking about I assume is the UL listing. Yes, the UL is an important factor and normally distingusihes that the manufacturer of the OWB paid to have the product inspected and received the thumbs up approval. However, lets not confuse the UL rating with air quality issues. Air quality is not part of the UL approval, a common misconception. The agency responsible for air quality is the EPA. An OWB may have the stamp of approval from the Underwriters Labotories stating that the pop-off valves are installed correctly, the steel is adequate etc. but it does not address the potential for emitting pollution. Again, that is a EPA responsibility. If you do contact a building inspector before installing an OWB he should check that the product is UL qualified. He will also ensure that the device is installed according to local codes, but what he will not do in most cases is disapprove the installation based on the potential for pollution. Of course if the township or state has banned OWBs or implemented set-backs and chimney heights, the inspector will address those issues. So the bottom-line is: a UL label will not give you immunity from a law suit for smoke and odor.
Next point, yes OWBs are considered a whole house heating system and they do burn significantly more wood, but they also emit more pollution per hour than a typical indoor room wood burner. That is the point and the problem. I have seen studies that try to justify the amount of pollution an OWB produces by stating pound-for-pound of wood burned an indoor wood burner and OWB produce similar amounts of pollution. The EPA conducted this study years ago when OWBs began to migrate out of rural areas into suburban america. OWB manufacturers cherry-picked the study and pulled out a small section of the report that talked about the the pound for pound clause and used it to try and convince law makers and consumers that the amount of pollution emitted from an indoor wood boiler was the same as that produced by an OWB. But a careful reading of the report shows that the quantity that is important is the grams per hour that is produced not pound for pound. To a person trying to justify purchasing or a person defending an OWB purchase it's the kind of subterfuge they'll grab onto. Law makers ignorant of technical issues also found it convenient to use, but since then subsequent reports debunked the deliberate confusion.
I do agree that you should go to the dealer and quiz him. But the problem you'll run into is there is no way the dealer can reproduce the actual set-up you'll have at home. For example, if you have a 3000 SF home and the dealer suggests you purchase a 5k unit you won't know how it will react with respect to smoke and odor till you get it home an hooked up. The dealer will most probably start a small fire, burn it extremely hot and say look no smoke. With no load on the furnace and no building representing the square footage of your home there is no way he'll be able to emulate your set-up. I suggest you find someone who has purchased the model you're looking at and go see it in October, Jan, and April.
OK let's discuss sizing in a little more detail. Did you ever know anyone that installed their own air conditioner and over sized it? What happens is the unit will rapidly cool down the house but because it wasn't sized properly it won't remove the necessary humidity for comfort in the process. This is somewhat similar to oversizing an OWB but the bill payer will be your neighbor. Many smoke problems could be solved with the new Phase II units if the dealers would insist on properly sized units. Unfortunately, they make more money when they sell a larger unit. If the manufacturers would pull their heads out of their *** and looked at the big picture they would realize for every oversized unit sold there is a potential for an upset neighbor and an enemy for life. An enemy that will join with others around the nation and fight them with every fiber of their being. I have seen this happen over and over again and it will continue to cost manufacturers in ways they can't calculate.
Lastly, as long as there is cycling of the damper, oversized units being sold, and semi dry wood (over 20%) being used, achieving real gasification will be difficult unless a secondary heat source is employed keeping the fire burning hot between cycles thereby sustaining the gasification process. Manufacturers know as well as their dealers do that if you size the unit to the house the wood burns up quicker and you'll be outside reloading in the wee hours of the morning. There lies the catch 22 for manufacturers.
The so called Phase II technology is not ready for prime time until these issues can be addressed. Perhaps this is why CB now has in its owners manual that they are not responsible for nuisance conditions created by their product.
