I can tell you 100% that mine wouldn't cause a 150 degree difference. Mine can't even blow a candle out.
2022/23 VC Owner thread
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Well if the heat radiating from the base is spinning the fan its really just wasting energy spinning the blades. I would think it just really acts as a radiator, which should certainly do something.
I agree it seems ridiculous. Certainly the biggest part of the 150 degree difference is comparing repeated max temps before the fan with average temps after. However. Since installing the fan I haven’t once intervened for griddle temps. I also got the Auber the same time as the fan. So likely I’m running the stove significantly different.
I think my installation has a significant lack of air motion around the stove. If your stove is in the center of the room with air freely moving around it, you likely wont get the same results.
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I really thought about buying one of those fans but I plan to install a ceiling fan which will be ten feet away from the stove and about eight feet high. My hope is that I will have a nice even distributed heat in that room while also circulating air into the next with a fan pointing from the non stove room into the stove room. Right now from cold start it takes a full day to heat up the next room and if I use a furnace to warm that area first , half a day to maintain that rooms temp as long as I set my furnace to 68 or lower otherwise the furnace will kick on from time to time
Looks pretty good to me. That's what I hope to achieve and wake up to. I can get there or even better but there are times I nutter things up by going a bit lower than I should because my fire seems to strong at bedtime so I assume it's because I have more oak than usual and I'll wake up to 1/2 the glass being heavily fogged because I reduced the air too much.
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I’ll take picture of my glass in the am. Right now we are running warm. It’s 75 in here and I’m going to let it go for the night.
That's about the largest of splits I put in my stove, and yea that makes for a great morning split to put in on a nice bed of coals and just let that run on it's own with maybe two smaller on top to get that stove going nice and hot, then around noon or 1 you can load it up
dont you hate how the ash just pukes out when you open the doors. I have a little vacuum that I have dedicated to this (and because I couldnt find another use for it as it sucks but not in the way it is supposed to)
What a cute baby stove..... what length log you got there? 8".
Sorry I could not resist..... Its a lovely stove.Yea it's why my wife liked Vermont casting. The stoves look decent. I don't see anything glorious about them aside from looking at steel stoves and just knowing I don't like those. We picked the dauntless which is a bit bigger than the one newguy132 has, but not by much. It heats a 650 sq ft area with cathedral ceilings and no fan, fairly well. Heats other areas as well but not as much as I'd like. And during warmer temps I struggled to keep temps down without creating creosote so I have to just burn one or two pieces at a time.What a cute baby stove..... what length log you got there? 8".
I close mine down at night and the glass is black in the AM after a 11-12 hr burn. No big deal open the air and let it burn and the glass cleans up, it's a cycle of that every day. I can't see the fire when I sleep so it doesn't mean much to me about the glass getting black.
Clear and cold this morning and the cat reacts fast to the increased draft even with just a few splits in the box.
Clear and cold this morning and the cat reacts fast to the increased draft even with just a few splits in the box.
That size split was me looking for smaller splits to get the fire going and finding something medium size. One I have a good coal bed I’ll put a 6X6 split on with a couple 3x3’s or so. The bigger they are the longer they burn.That's about the largest of splits I put in my stove, and yea that makes for a great morning split to put in on a nice bed of coals and just let that run on it's own with maybe two smaller on top to get that stove going nice and hot, then around noon or 1 you can load it up
dont you hate how the ash just pukes out when you open the doors. I have a little vacuum that I have dedicated to this (and because I couldnt find another use for it as it sucks but not in the way it is supposed to)
Yea the ask coming out is a giant pain in the ass. My wife has decided that she needs to use the Dyson vac to clean it up and it clogs the filter every time. I have a giant shop vac that it doesn’t phase, but it’s a bit much to haul that out of the garage all the time to suck up some ash.
Haha I know it’s tiny. I would have loved a bigger one(and honestly need a bigger one) but everything else was too tall and I would have had to redo the hearth. I went to the stove store looking for a Dauntless. For how tiny it is it does a good job of heating the first floor. Once this little one craps out I’ll probably end up with some sort of jotul. They make short leg kits so I can fit a bigger stove in the same opening. That’s probably a 12” split. 14 is the recommended size for this little guy.What a cute baby stove..... what length log you got there? 8".
A lot for my pea brain to digest here..... Like all people of limited capacity I am going to break it into chunks....
I agree, a couple thoughts I had
- the draft combined with the area of the EPA holes will set the amount of air delivered. Actually to be more precise... it would be the draft minus pressure drop through the cat /secondary. If the secondary is really hot, pressure drop will go up thus reducing the amount of primary air delivered. (I am assuming constant draft as measure at the stove exhaust)
- You explanation made me question.... what creates fuel for the cat? It is heat, which of course stems from the air flow, but can also be provided by a bed of coals (for some period of time) I see you specified "steady state" so I agree with your statement but I think it might be oversimplifying. Cat fuel can also be provided for some time with zero air via the stored thermal energy in the stove and coals..... but that is transient and outside of what you specified.
I am struggling to understand the theory here.....
- Fuel does not flow through the little holes (I have 8 btw) that is all air.
- Where doe the large increase in secondary air come in? The secondary holes are relatively small and a tiny change in draft is not going to change flow through them much....
- If you add more fuel and air to the cat the flame temp does not necessarily go down, if you add them in the same proportion the flame temp is unchanged. If you change the proportion of fuel / air then temp change depends on which side of stoich we are on.
- Increasing fuel/ smoke to the cat will increase cat temp (I am assuming lean operation here)
- That increases draft which induces an increase in secondary air flow and lowers cat flame temp.
- Increased draft also increases primary air flow (unless the pressure drop through the secondary also increases, then maybe not)
- By plugging the secondary holes I think we are pushing the burn to the rich side of stoich and thus temps are reduced, but all the fuel is not burned because we have limited air. So it reduces temps but at the cost of lower efficiency and higher emissions.
Not sure why you think that. My flue does move, it tracks with cat temp. Maybe point to an example that caused you to think it did not move.
That's correct, the incoming air is preheated by heat from the secondary and primary burns through the cast iron.
On my stove the primary flapper is closed at about 40% travel with stove hot (griddle = 450). Just checked it again....
All the bimetal does is close the air down when the stove is hot, you as the operator can only introduce a bias to the flapper control, as the stove gets hotter the bimetal closes down the air. The lever controls the flapper position but the bimetal has authority. For example with a hot stove (say 450 griddle) the flapper might be closed with the lever at 50% (straight down). If you move the lever forward the flapper will open increasing the temp of the stove, as the stove temp increases above 450 the flapper will begin to close gain, maybe now it is full closed at griddle = 650 (making up numbers here)
I have diligently set it this way, earlier in my career I did not have it set this way. I learned through experience, to set it according to the manual. I do not think the setting is that critical because the bimetal helps correct any small errors in the adjustment. I the stove gets too hot it closes the flapper more.... Certainly there will be some effect on the temp it controls to, but I think pretty small.
Now if the flapper is hanging up that would be a much bigger affect, that would completely remove all bimetal control at lower air settings, or with the stove hot and cruising. In the past I tried adding a rubber band (spring) to the cable to provide some seating force for the flapper to overcome any friction. As I recall it was not effective, but I may need to try again. It certainly biases the temp control to the cold side which I have to compensate for with lever positioning.
One thing you did not mention that I have been thinking about for years..... what id the secondary air does not all go to secondary combustion. What if some of it also supported increased primary combustion. It would give you the same kind of affect, runaway at temps. If you look at the older stove designs they way they bring in secondary air makes it almost impossible for it to increase the primary burn. In our stoves it is pretty easy to envision how the secondary air could support primary combustion.
In conclusion...... Far be it from me to argue with Mr. Spock, the great analytical thinker of our time, but that quote was stolen directly from the great Sherlock Holmes as best I recall...... The trues for of flattery is imitation....
This was a lot of critical thinking for me.... I need a nap.
Glad to hear it’s not your primary air flap. I guess we’ll add that to the list of impossible and keep looking for the next improbable.
User error
Dont you just love hearing that when you've spent more time/effort/scientific reasoning on a wood stove, than if you were in a scientific industry or an engineer and do that work during the day? HA
Lol. “I think you’re under-thinking this” said no one to an engineer. Ever.User error
Dont you just love hearing that when you've spent more time/effort/scientific reasoning on a wood stove, than if you were in a scientific industry or an engineer and do that work during the day? HA
-2 out here with a windchill hovering between -19 and -26 and the Dauntless is barely keeping up with the boiler set at 67. STT at around 500 for the past 7 hours. I have to time my reloads with a lull in the wind. I am getting some blowback smoke with the big gusts. I don't have much hope for it with tonights -19 and -40 windchills. Tough conditions for the Dauntless.
The Dauntless likes to send heat up the pipe, I think their ratings are grossly exaggerated. The top gets hot and stays hot long before the sides can catch up. To be expected to some degree I guess but some of the other stove designs make me think they are better designed.
On my third part load since 6:00 AM. STT > 550 all day. Cranking hard. Cat hit 1650+ this morning but it has been more tame with smaller loads.
Put my rubber band back on the flapper this afternoon. Cats at 1100 right now and hovering, perfect. For now.....
Brought the first floor from 60 to 74 today. Bedrooms still at 60.... maybe the wife will want to snuggle..... Thermostats still off.
Not saying it is definitively not the flapper..... but I have investigated before and come up empty. Maybe it is hanging up on me..... Worth checking again.
Your explanation of flow is much more correct. I was thinking about the firebox as just a box of hot gaseous fuel and air. If anything leaves, it has to be replaced. Certainly a larger volume of hot (less dense) air can leave and be replaced by a smaller volume of cool air. Once the temperatures are the same, it balances out.
The error I made is that I assumed a constant fuel concentration in the air leaving the fire box. Under that (horrendously incorrect) assumption air coming in is a proxy for fuel leaving. This is probably the main factor that drives the equilibrium temperature the catalyst is always driving towards. This is likely something you’ve already understood. Thanks for your (everyone’s) patience. I’m still catching up.
I think we pretty much agree on the feedback mechanism that is responsible for the flat catalyst temps these stoves exhibit (sometimes even at a desired temperature).
I agree that your flue temps move. Maybe what I should have said is this: what if you programmed your watlows to run a blower between the back casting and heat shield? Not changing anything about the air going into the stove but just forcing more heat to be pulled off the stove. If you drop your flue temp, draft decreases, fuel and air to the cat decreases, temps go down. Unfortunately, You can swing 1000 degrees in catalyst temperature and gain 100-200 in flue temp. Increasing heat transferred such that your flue temp only rises 150 degrees instead of 200 isn’t going to stop your runway catalyst train.
FWIW I fully acknowledge that secondary air is contributing to primary combustion.
Appreciate the proper credit for the quote.
Ok so the thought is to extract more heat from the back of the stove to reduce exhaust temps which will reduce draft. I have already achieved this by installing my more restrictive damper, I can drive draft way down and it has slowed the stove down a bit, but it still overfires frequently on a full load. It is shocking how little open area I have with the damper full closed. I get more frequent occurrences of back puffing with the damper closed, (as one would expect) but it does not happen often.
Every year I think about this some more and keep coming back to the primary to secondary air flow ratio is not correct for some reason. Just feels like the primary is making more fuel than the cat can handle. But I also think I may be bouncing between too rich and too lean depending on conditions. When you do not know which side of stoich you are on, it is hard to know what to do,.. I need to get an oxygen sensor in the stack and see how much excess O2 is in there..... I might have an old automotive unit kicking around I could make work, another experiment....
bert670
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THANK YOU!
This is an example of the 'orange glow' that I refer to when I say you should always run your stove to the point that you see flames UNLESS you see this!
This is exactly what Im talking about. So much satisfaction as I keep forgetting to get a picture.
Is there more wood in there above the glow line or is this toward the last 1/3 of the burn time for this load?
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