Woodstock Fireview Flue Temps

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Todd

Todd

Minister of Fire
Nov 19, 2005
10,342
NW Wisconsin
Calling all Fireview owners. Seems there is some variations on flue temps out there. Was wondering if everyone could chime in and give their temps whether external, internal and where abouts the readings are taken from. With a full load of hardwood my internal temps (condar flue probe) at about 20" above the exhaust collar runs anywhere from 500-700. With an external magnetic thermometer it reads 200-400. Where are use guys and gals at?
 
Todd said:
Calling all Fireview owners. Seems there is some variations on flue temps out there. Was wondering if everyone could chime in and give their temps whether external, internal and where abouts the readings are taken from. With a full load of hardwood my internal temps (condar flue probe) at about 20" above the exhaust collar runs anywhere from 500-700. With an external magnetic thermometer it reads 200-400. Where are use guys and gals at?
Click to expand...


Todd- I think I'm one who has reported lower flue temps than you're seeing. My original install is still runs about the same~300F.
Over the summer I installed a second fireview and new chimney set up. This one runs the flue straight out the back of the stove about 2 1/2 - 3' to a tee and then up 21'. Supervent set up. A tel-tru probe thermometer 200-1000F is installed in the horizontal dbl walled connector pipe about 20" from the back of the stove. I've have not burned this one much*, but so far it has run higher flue temps (~450F) than the original stove/install. Perhaps I need to replace the thermometer on the lower reading setup.

*only hit 600F stove top temp once so far, perhaps only one full load of hardwood - just not cold enough to fully load it.
 
I have single wall pipe (purchased from Woodstock). 90* bend up about 2' then 90* bend to take it to ClassA through wall to T and up outside the house.

Checking temps on the surface of the single wall during burn 18-20" up from the top of the bend I get temps around 200* when surface temp is 300-400* I measure both with magnetic and check with the IR. I've not yet built a table of flue vs surface temps but plan to as it seems there should be a relationship. I have yet to get my stove surface temp over 400 for a significant period of time more than once - simply don't need that heat yet! I've been burning it long and slow just about every day though.

Once the burn is past the prime and surface temp is down to 250 (where it sometimes sits for hours on end) the flue may go down to between 100 and 150 which I actually sometimes wonder if it is actually too low - I wonder about my draft and actual temps at the top of my stack (condensation of water etc).

More data when I have it :) I too am very curious about this topic.
 
I would be a little worried if the flue temp within 2 feet of the stove was much lower than the stove temp. I would suspect a bum meter in that case.
 
From what I've read, it is common for both the Blaze king and Fireview cat stoves to have lower flue surface temps than stove surface temps. It does seem weird, but somehow it works out. I rather like the idea - seems to imply that more heat stays in the room to me.
 
Condar probe, 22" above flue collar, average is 400 with stove top at 425 at 0.75. As many have said, little need to push it yet as I'm mostly just burning a load at night.

Also, I am amazed at how long the top stays at 250 once the vast majority of the load is burned.
 
Highbeam said:
I would be a little worried if the flue temp within 2 feet of the stove was much lower than the stove temp. I would suspect a bum meter in that case.
Click to expand...

Au contraire, you forget the magic of the cat!
 
Did I? You said you were at 425 stove and 400 flue. That's pretty close.

Please remember that using the surface temp of the pipe to measure the temp of the flue gas is like checking for cooked chicken by eating the skin.
 
Condar internal flue probe 18" from top of stove on double-wall stove pipe.

During startup, I like to have it between 500-700 degrees F. Once cat is engaged, I like to have it set from 350-400 degrees F. When burn is at end it has dropped a lot lower.

The Woodstock Fireview manual states that the temp should be between 300-350 degrees I believe.

Mike
 
MacPB said:
Condar internal flue probe 18" from top of stove on double-wall stove pipe.

During startup, I like to have it between 500-700 degrees F. Once cat is engaged, I like to have it set from 350-400 degrees F. When burn is at end it has dropped a lot lower.

The Woodstock Fireview manual states that the temp should be between 300-350 degrees I believe.

Mike
Click to expand...

Question - when you have your internal flue temps at 350-400f and cat engaged, what are your surface temps running?
 
Highbeam said:
Did I? You said you were at 425 stove and 400 flue. That's pretty close.
Click to expand...

That is an average during the first hour or so of the burn. Currently, the top is at 425 and the flue is at 300.
 
I just got a note from Ron at Woodstock who said not to let the flue get above 500 internal before engaging the cat. I had been letting it get up to 700-900 so I will need to start shutting it down much earlier.
 
Now that is quite interesting. I wonder if that is just a matter of wasting wood/energy or what? I always thought it was "at least 500f" for the flue gases to get cat ignition. Did he elaborate on this?
 
Can the cat "cool" the air? Seems that the cat might be 1000 degrees, and the fire might be making smoke at 300 which will pass through the fine honeycomb where I would expect it to heat up some.

Maybe the fire is making smoke that is only 150 degrees, which is raised to 300 through the 1000 degree cat, and the cat heats the stove to 400.
 
wendell said:
I just got a note from Ron at Woodstock who said not to let the flue get above 500 internal before engaging the cat. I had been letting it get up to 700-900 so I will need to start shutting it down much earlier.
Click to expand...


Wendell, I'd get back to Ron on that one. I believe what he meant was if you have just a stick on thermometer on the pipe to not let that get above 500 degrees.



Highbeam, why try to get so technical? Just sit back and enjoy the heat. Relax.
 
Todd said:
Calling all Fireview owners. Seems there is some variations on flue temps out there. Was wondering if everyone could chime in and give their temps whether external, internal and where abouts the readings are taken from. With a full load of hardwood my internal temps (condar flue probe) at about 20" above the exhaust collar runs anywhere from 500-700. With an external magnetic thermometer it reads 200-400. Where are use guys and gals at?
Click to expand...

Todd, if my memory is right, our external thermometer always reads 200-300 or maybe just a tad higher; maybe 350.

Ours runs horizontally about 3' to a tee and SS up the exterior of the house. No chase. No problems. Lots of heat.
 
Highbeam said:
Can the cat "cool" the air? Seems that the cat might be 1000 degrees, and the fire might be making smoke at 300 which will pass through the fine honeycomb where I would expect it to heat up some.

Maybe the fire is making smoke that is only 150 degrees, which is raised to 300 through the 1000 degree cat, and the cat heats the stove to 400.
Click to expand...

I don't know the answer either. However my best guess is that at the point of combustion the energy is released as radiant energy that is being absorbed by the stove and then conducted out to the room. Design of the burn chamber would have a lot to do with how this is being channeled - keep in mind that it is not a direct path from the cat to the flue. Now, the exhaust of perfect combustion would be water and carbondioxide - the water would of course be steam which has a decent specific heat, however I don't think the C02 has a very high value. Perhaps these gases overall simply don't carry the heat away as well as less combusted fuels.

The other factor here is the flow rate - I believe (but am not certain) that the rate the exhaust is traveling through the flue is slower with these stoves than with other stoves. This would allow more time for transfer of energy out of the stream.

So, the exhaust may well give up it's energy pretty easily to the stove on the way out as well as to the first bit of stove pipe it encounters - keep in mind we are measuring the temperatures almost 2' away from the exhaust port.

Just some speculation - whatever the case, it does seem to work. Sure wish an actual stove engineer would jump in here and explain :)
 
Dennis, I did double check with him and he was clear it was around 500 internal. I had been letting it get up to 900 and he said that is way too high.

He is a member here so I asked him to pop in to clarify.
 
Dennis, I did double check with him and he was clear it was around 500 internal.
Click to expand...

I think this makes sense, because that internal flue temp reflects (roughly) the internal stove temp. 500 degrees F is when the cat should be engaged (250 on top).

Mike
 
Yes, but does it hurt anything to go past 500? Maybe the shock of sending that 900 degree air into the cat is hard on it.
 
Question - when you have your internal flue temps at 350-400f and cat engaged, what are your surface temps running?
Click to expand...

Slow1,

The flue temp is relative to the internal stove temps, but when I had it the highest it's been at (570 degress F) since I had the stove, the flue temp was around 425-450, with a setting of .75-1, I think. This was when Dennis helped me out with feedback. I opened it up a little and the flue temps went up while the internal temp dropped.

Mike
 
wendell said:
Dennis, I did double check with him and he was clear it was around 500 internal. I had been letting it get up to 900 and he said that is way too high.

He is a member here so I asked him to pop in to clarify.
Click to expand...

Well then Woodstock better get together on this because they told me it was no problem engaging at much higher temps when I asked about this last year trying to figure out why my combustor was getting hairline cracks. When I fire up a new load with the bypass open it is very easy to reach temps over 1000. I engage over 500 every single time and it's more like 600-900 and it isn't like there's a raging inferno in there when I flip the lever. In fact if I waited til it dropped below 500 I'd be smoking out the neigborhood. If I see internal temps over 500 at 20" above the collar I know the cat has to be active and it is usually glowing at that temp or above. I would say 600 is an average flue temp for me with a full load of Oak. It also seems like the flue temps are close to my stove top temps like Highbeam was talking about. Seems my internal temps are higher than most and I have tried a damper in the past but the temps didn't drop that much. This is also my second Condar probe and the first one read the same temps. I wonder what gives here, I still get long 12+ hour burns, plenty of heat and can shut it down to where there is just a smoulder, so it doesn't seem to be overdrafting. Maybe I need to take Dennis's advice and just sit back and enjoy the heat?
 
MacPB said:
The Woodstock Fireview manual states that the temp should be between 300-350 degrees I believe.

Mike
Click to expand...

Only thing I could find in manual is stove top temps over 250 to engage the cat, which should equal about 500 internal. Most people aren't as anal about their temps like some of us here so Woodstock makes it easier for most by instructing people to just monitor the stove top temps. There is a hole in back of the stove to stick a cat probe into so you can monitor the cat temps, but it's hard to read being in the back. I had one in there when I first had the stove, but it failed in a few months so I never bought another.
 
Only thing I could find in manual is stove top temps over 250 to engage the cat, which should equal about 500 internal.
Click to expand...

I'll look for it. On page 29 in the troubleshooting section, in "Stove Not Burning Hot Enough" subsection, it states that stovepipe should register 200-300 while combustor is engaged. I'm assuming that's single-wall stovepipe and the internal is a little higher.

I'll try to find the other reference to stovepipe temp.

Mike
 
Todd, is that 600 flue temp after the cat is engaged?
 
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