Peter van den Berg wrote:
Markus Padourek wrote:Thanks for the information Peter, that does indeed help a lot. The idea would be to have well-insulated houses, and at list for our house designed with passiv solar principle, but not to passive house standards. And how long is each run for you on average?
Duration of a single run is something between 45 minutes and 1 hour, depending on fuel species.
Markus Padourek wrote:I did not know there was a difference between smoke and vapor plume (I am still relatively new to this topic) - what exactly is vapor plume?
Vapor is moist air, lots of water in the exhaust gases. On a chemical level, result of complete combustion is heat, CO² and water. One kilogram of absolutely dry wood will produce 0.5 liter of water. In the exhaust gases this water is in gaseous form so it won't condensate in the chimney as long as the exhaust temperature is above 45 ºC.
Markus Padourek wrote:Is this purely because the hot air meets with the cold air?
Yes, the steam condensates in the cold air as droplets which immediately spreads out and makes clouds of visible "steam" (*fog*) until it spreads out enough to evaporate again. Often the visable plume begins some distance above the chimney exit, 30 cm (1 ft) is no exception.
Markus Padourek wrote:And apart from the different smell this is clear visually because it is purley white fumes, rather than the typical dark ones, right?
Yes, the smell of wet charcoal is from 9-methyl ketone in very small quantities, real complete combustion is very, very close then. Real smoke moves much slower and tend to drift away without disappearing.
Markus Padourek wrote:Also I would be curios, which batchrockets results do you know of? I only know of https://www.uzume.fr/
There's one Dutch guy who used the technology to build his own heater but refuses to recognize my work. He had his heater tested, one page of the report is here:
Another guy, from Belgium this time, implemented his own heater much later, his result page is here:
Peter van den Berg wrote:
Markus Padourek wrote: - How long does one generally need to run a RMH for a day in a northern climate for a small house (30-60m2)? 1-2h? And would it be possible to reduce that with passive solar, that on sunny days one might not even need to heat?
It greatly depends on the level of insulation, but in our passive house in the Netherlands we use a 150 mm batchrocket system with a weight of two metric tons. Our house is larger, but the heater is run one charge of 3 to 6 kg soft wood species in the evening while it isn't freezing. The load is tailored to the weather forecast, more sun during the day means a smaller load. During frost periods we run it twice a day, during breakfast and diner. We had a cold spell in February with lots of sun during the day, one evening charge being enough. I have to admit the house sports a lot of glazing facing south, this helps a lot!
Markus Padourek wrote: - If one burns correctly, how much smoke is there visible over the duration of a whole run? I assume there will be some smoke at the start-up and maybe the end? Are there some videos that could be shown?
In a mass heater the core won't cool down completely between burns. We emploi the top-down lighting method, which emits a very little bit of smoke for about 5 minutes during startup. There's lots of water vapor visible during most of the burn of course, exit temperature at the top of the chimney is estimated between 80 and 100 ºC most of the time. This vapor plume dissolves in the air within a couple of meters and is transparent most of the time. It's appearance is much alike the vapor from a condensing natural gas boiler.
No smoke at all at the end of the burn, definitely.
There's a very old video, illustrating what is visable in frosty weather. At the time I could stand there, my head in the plume and frantically sniffing, only to detect a very faint smell of wet charcoal. Mind you, it happened to be a large fire that was raging in my workshop at the time.
Markus Padourek wrote: - How long is the "start-up" phase of a well-built and well-lit batch-box or dsr RMH? Some people were specifically worried about that phase, knowing it is the most polluting one and arguing that one central stove, distributing the heat to all houses, would be more efficient and reduce the pollution from the start-up phase (which I don't think I agree with, if we also consider line-loss and other possibilities we now loose, like cooking, etc).
Starting up time of a warm-but-not-hot batch box rocket is about 5 minutes, 10 minutes tops.
Markus Padourek wrote:Edit: I have also not found resources that go into details about the exact particles that come out of a RMH exhaust and how they compare to other woodstoves (mostly interested here in how dangerous they are for humans), but given that there are RMH here in the EU that have been certified and are far surpassing the current 2020 regulation as well as the upcoming 2022 regulation, I hope that this will provide enough security for people on that front.
Personally, I've seen the results of two tested batchrockets. First and foremost, those things emits very little smoke to begin with, the dangerous particles are organic, i.e. soot. The particles that remain are anorganic, the residue that can't be burned because these are the minerals that are taken up from the soil by the trees. The limit of dust concentration in the 2022 EU rules is 40 mg/m³ if I remember correctly, both the two rockets did 20 mg/m³. Both were bell constructions, which means gas velocity nearly stalls while entering the bell, so most of the dust is settling at the floor of the bell. The first time I checked my heater I stuck my hand through the cleaning hatch and I couldn't feel a thing. I tried again and waved a bit with my fingers, there was some resistance then. Very fine dust, not what one would call ashes from wood burning.
Suffice to say, batchrocket don't sport an ash drawer because there's no need to, anorganic ash particles are a very very small percentage of the wood's makeup.
I hope this helps.
Skandi Rogers wrote:Those two sites talk about masonry stoves which are indeed common and I doubt that type would be any issue to get certified. I just remember a discussion here that was talking about issues connecting a rocket to a normal chimney, which would then cause an issue here. The solid residue printed on the bags of pellets varies between 3% and 4.5% ish. we notice a change in the ash if anything is slightly off with the furnace. wiki states somewhere between 0.5 and 1.4% as being unburned at over 750C (1380F)
Skandi Rogers wrote:I would say before you bother with all that find out how to connect one to a standard chimney, you have to have it swept and inspected either once or twice a year (it's twice in my present house, was once in the previous) that is a legal requirement and cannot be avoided once bbr has the heating type down. he even has to inspect the second chimney that is not in use and hasn't been for several years.
There's a few threads lying around here on RMH heater smoke and as far as I can see nothing has been actually checked on particle size.
You could try the money angle as well, a central pellet furnace will cost a fortune to run (but produce no visible smoke), straw while it is cheap requires a tractor and really smokes a lot. ground heat would work but is expensive to install and it appears it has a limited lifespan, air/air heatpumps are probably the most obvious solution.
If you figure out how to get one properly allowed can you make a thread on how to do it? it could be very useful for others.