Production Woodstock IS

I'm a little lost on what and how you did your math to get your figures TheRambler .
Welcome to FHC btw...
Happy Thanksgiving!

 

I'll throw out my .02 on your temps. First off I think you have one of the older Condar cat probes and with all my experience changing out different probes and comparing with thermocouple I'd have to say your OK and its probably 200-400 degrees less. Condars new cat probes have a different dial face and only goes up to 1700 verses 2000 and I think its a little more accurate but these types of probes are slow to react and are also skewed by radiant heat effecting the coil since it sits so close to the stove top.

I've also contacted Condar about cutting off the probe and they told me it shouldn't effect the readings.

If your really looking for accuracy a thermocouple is the way to go but these Condars are a good tool and close enough once you get your burning habits down.

Another thing you could do is contact Woodstock and ask if they can send you a spred sheet on temps of an IS burn to compare with yours. I've gotten a couple and its pretty interesting.

 

Those look like straight heat- transfer numbers. That would work if the inner surface was at the temp. shown, and the transfer was through nothing but a solid piece of material such as steel or soapstone. But what is happening here is several changes of materials as well as the size of those materials so a simply constant as a multiplier will not apply.

The combustor is not up against a piece of steel but rather several inches away from a piece of steel much larger in area. So the transfer is almost entirely radiant, then through the material (the steel radiator in the case of an I.S.), then radiant again to an even larger area of a couple of pieces of steel (the top and front plates) and finally through those materials directly. Because of the gradients of temperature across all the materials, it would be difficult or impossible to calculate the heat transfer or even heat transfer rate. A better way to go IMO, would to to take a thermal image of the outside of the stove at normal running temp. and calculate how much heat is being given off going by the temperatures of the outside area of the stove.

Another really large variable that we do not know is gas flow (Easy Boys! not THAT kind of gas): how much air is flowing into the stove, and how much flue gas is flowing out of the stove (the incoming air mixed with the volitiles of the wood)? That could be directly measured of course but would take more sophisticated equipment than most of us have lying around.

But all the way back to the object here: if the combustor is really running at, say, 1,300 F (a reasonable guesstimate in my very limited experience with this stove), the steel radiator above will be at a much lesser temperature but be flowing nearly the same amount of heat, which again will be passed onto the surrounding stove steel (mostly the top along with small areas of the front and back of the stove) which will be at a much lower temp. yet than the radiator but still flowing nearly as much heat. In the end, the temp. of the source of the heat is far less important then the temp. of the device actually radiating the heat into the room along with that device's temperature. An example would be baseboard hot water heat: we really do not care if the boiler firebox is running at, what is of interest though is the average temperature of the baseboard and the area of the baseboard as that is what is actually heating the house.

Brian

 

I think we need to narrow down our use for the numbers we are measuring before figuring out which spot is important. For me, I want to get as close to the air pocket the cat will be sitting in when engaged. That will give the best measurement to time the engagement.
I agree that airflow would be fun to look at. An automotive style MAF sensor that reads low enough would work but I doubt they read that low. I think if there is room to squeak out any more efficiency it will be through accelerating the air, either passively or actively.

 

I measure the temp. at four points: inside the firebox, at the upper / left / front corner, just above the combustor, on the stove top just to the left of the flue pipe flange, and just before the smoke pipe enters the thimble (with a probe for actual exhaust temp., not surface temp. of the pipe). My interests are 1) to get the flue temps. down, along with the airflow rate, to get as much of the wood's heat output inside the house where I can use it. 2) to make sure the combustor is lit and 'combusting'. 3) the stovetop is a <reasonably> indicator of the stove's heat output.

I have found that the stove will run without any visible smoke at much lower temps. than I would have thought; I can typically run the firebox between 400F and 500F with the combustor between 750F to, say, 950F, burning all the smoke and yet with stove top temps down below 300F and flue temps. under 325F or so. This allows me to run the stove a long time (18+ hours) on less than a full load of wood, keep my entire house above 73F and have more than stove left that is more than 1/2 full of charcoal.

I also use the temperature differential between the firebox and combustor temps. (or the combustor 'input vs. output' temps.) to know when I can close the bypass and make sure the combustor is 'lit' immediately after closing the bypass (the firebox temp. drops immediately and the combustor temp. climbs w/in one minute or so).

The actual cruising temps. of the stove are not that important to me once it is stabilized at some level set by the draft setting.

I believe if we actually did measure the airflow through the stove, it would merely point out that it can basically be dismissed. Air has very little heat capacity, and once the stove is down below, say, 1/4 draft setting, I just do not think there is much actual heat lost up the chimney. Of course the catch is that we would have to measure to know we did not care about it

Brian

 

I have found the probe thermometer I have 18 inches above the stove is already a good tool to time the cat engagement, and the stovetop thermometer near the collar is a decent indicator of when to start shutting the air down (ie: when the secondaries will light). The probe for the cat thermometer will get me closer to hyper mileing the IS and I think at that point the next step would be to measure actual temps at the top of the firebox- but I doubt I will go that far.

 

Brian, I am looking to airflow as a way to get the cat hotter faster, and for longer.

 

Smoke spillage on reload is proving to be a real pain in the @$$. My chimney is double wall insulated stainless, strong draft and nothing helps. The smoke flap doesn't do blap.

 

That sucks. [knock on wood] I've had some good results with a decent prevailing wind and a 26 flue run.
Do you get any backpuffing?

 

Yeah, I was at a friend's yesterday and asked him if he could open the door on his Jotul all the way without smoke spillage- he said sure and then showed me. Smoke literally billowing out the front door Again, it is not the stove maker or any flaw or fault, it is just a matter of having a huge hole in the front of the stove with the only outlet being a 6" pipe (plus what rolls out of the top of the stove door opening of course.... :-( ).

I tried a draft inducer (fan) and while it worked, it also had enough problems that I removed it. But after tinkering with it, I re-installed it, sealed it and now it works pretty well overall. I can fully open the door of the I.S. without any smoke or flyash coming into the room. Makes re-loading and maintaining the stove (raking the ash around) a breeze. The inducer was $150 delivered from Northern Tool. I can post a photo or two if you are interested.

Brian

 

In my short time running this stove, I am finding the key to getting the cat. up to temp. is to reduce the air supply to the firebox. The dedicated cat. air supply seems to supply more than enough air to burn any amount of fuel the firebox can generated. My highest cat. temps. always occur at 1/4 draft settings or just a tad below that.

Brian

 

I had the tertiary air in mind. I know it flows pretty well already but if there is room to get any more from it, I think that's where it is-- either disrupting the flow, smoothing it out, or accelerating it.

 

Don't know what things you've tried to reduce / stop the smoke spillage, but here's what has helped with our system:
The owners manual page 24. .... additionally:
1. I wait until ALL flame has burned out in the firebox before opening for a reload. This requires open up full the air intake lever AND open the cat sled for awhile (several minutes) to see if more flames occur. Wait 'til flames die off. Even then, there's that fat split way in back whose bottom didn't ignite. With cat open and air full, SLOWLY open the door and use the long rake to roll that unburned split toward the stove front until it's on the hot coal bed. Close the door - that fatty will complete burning.
2. When opening the door, first open the cat (you have to) and the air intake full open for a couple minutes. Then open the door to the door-cracked-open notch a couple minutes. Then open the door VERY slowly. It even helps to pause the door opening every 2 inches, pause, 2 inches, pause, etc. until about half opened.
3. Be positive sure there are no exhaust fans running in the house.
4. To LOWER the NPP (neutral pressure plane) in your house, before opening the IS, crack open a window that is lower in the house than the IS. (I think I got that right).
http://www.gulland.ca/fhs/temperature.htm

These EPA stoves are meant to burn a complete load before a reload, not to be added to in the middle of a cycle. Yes, the stove will cool alot during the coal stage (mostly at the end).
Following the steps above has helped with smoke spills here nicely. If you have done the above stuff and still get spills, then it's beyond my pay grade to grok it out.
Just tryin' to be helpful.

 

Brian,

Thanks for your note. You have the Tjernlund AD1.....it will not work on my setup as I have double wall stove pipe and the AD1 is designed for single wall. Gark, thanks for your input and I'll give your tips a try.

 

After raking the coals forward as well as a lot of the ash in the firebox, I find the amount of ash that's produced is very small. And the ash is very fine and dense. I have burned nearly 1/2 cord so far and just emptied the ash pan and some loose ash in the stove itself, it only amounted to about 3 gallons total.

 

Did you empty the ash and pan with a cold stove or with hot coals still burning? I've been working the rake back & forth above the grate to get ash to drop into the pan, then empty the pan, sometimes with coals burning sometimes cold. I could be doing it wrong, should we just let the ash drop through on its own and only empty every 7-10 days like the manuàl says?

 

This was the first time I emptied this month (Nov). The ash pan was full and I took some from the firebox itself. I had a few hot coals still going when I did this, I pushed them to the side and worked the ash a bit. I filled an old sap bucket full, nearly 3 gallons, with everything collected.
On every reload, when I rake the coals forward, I rake the ash with it and it mounds up by the front door. This works good for me, I usually have a good working surface on the firebox floor in the back of the stove and when I reload I put two splits E/W and then the rest N/S on top of the two bottom splits. The second row will overhang the hot coals in the front and this is where the reload starts, the coals in contact with the second row of splits.

 

Sounds like you boys have been having "loads" of fun (or partial loads; as the case may be) with your wood stoves. All great info - and helps me and everyone reading it.

OK. Here it goes. Those of you who feel you have less than optimal draft through the stove - spare yourself and do NOT read the following:

Inspired by Darrin's report regarding his newly purchased/installed cat probe (easy Brian), I flipped open the top of the old girl to take a look. Yup, Darrin, you are correct, the @#*?&* carriage rod travels toward the cat just a little to far. That is why you (Darrin) cut the 6-1/2"probe shorter so as to allow the carriage rod to pass just beyond and below the end of the probe; cleverly avoiding the situation where the carriage rod would come down on top of the probe and push it into the face of the cat.
Well, here comes the controversial part. I removed the port bolt and shoved a piece of metal dowel in (I can hear who is snickering) 6-1/2" to simulate the probe, and operated the bypass just open enough to barely touch the top of my simulated probe. At that point in the travel of the carriage rod, I looked at the amount of the bypass opening as the sled shifted rearward. It looked about 75% or so open. I then placed a nut (the bolt kind) under the part of the carriage rod that acts as the "stop" (under the finger-like thingy on the left side of the carriage rod that protrudes toward the rear). The nut may be from a 7/16 bolt or larger. All's I know is it measures 3/4" tall and fit under the carriage rod stop with the carriage rod in the newly discovered postition; so the rod came close to but did not touch the dowel I used to simulate the probe. Then I lit the stove and discovered that for my particular set-up, the bypass was opened enough to allow the stove to function perfectly. No problem starting. No smoke on reload. So....I'm gonna order a 6-1/2" probe from Condar unless you guys can talk me off the ledge.....
Oh yes. I know who I'm dealing with. Don't get your corn all-in-the-popper about thinking that the 3/4" nut is gonna move every time I open the bypass. To my surprise (as well as yours) the little thing just sits there. Doesn't move a bit. Yes, I too am surprised.
OK - I'm ready......Let it rip.......

 

I'd like to see some pics if you get a moment to take some.
Looks like you found a way to make it work, very nice I was actually thinking the same thoughts as you when I was going through the motions too but I didn't want to affect the sled function in either direction. Can you agree that WS
may have been a little short on cat therm probe considerations when putting the carriage/sled together? I hope they can at least modify this for future IS models.

 

Be careful what you say on here. You just might be documenting a reason to void your warranty.