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"Driving off moisture" before engaging Cat

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Slow1, Dec 8, 2009.

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  1. Slow1

    Slow1 Minister of Fire

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    What moisture are we talking about here anyway? Clearly 10-15 minutes of burning won't lower moisture content of the wood to 0% or anything like that so it seems this must be referencing surface moisture, right? So does the time required to do this vary depending on how dry the surface is (i.e. if it was stored inside for a while vs sitting outside and rained/snowed on in the last day or two)?

    Besides waiting the time period, can one look at the fire and tell that it is ok to go ahead and safely engage the cat?

    The reason I ask is that much of my wood is VERY dry and since I have quite a bit of indoor storage - been burning less per day than last year so I have almost a week's worth in my rack next to the stove, the wood is surface dry as well as running about 15-20%mc. When I feed on top of a good bed of coals in a hot stove (surface temp in active cat range), I can have a raging inferno in the stove within 3-5 minutes with all surfaces of the wood engaged in the fire. Waiting for 10-15 minutes seems like a waste of time and fuel - by that time smaller splits near coals may already be coaling. I've reduced air to less than 2 but going down too far will reduce the inferno but result in smoke unless I engage the cat.

    I have gone ahead and engaged the cat after 5 minutes and it seems quite happy to glow along and burn, but am I risking steam damage here?

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  2. weatherguy

    weatherguy Minister of Fire

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    I hope not I do the same as you, I have some very seasoned dry wood that I stored in my garage so there is no surface moisture either, then again Im new to the whole woodstove thing.
  3. Lanningjw

    Lanningjw Feeling the Heat

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    I never wait if the cat is in the engaged zone on a reload before putting the by-pass down. I dont think the BK instruction say anything about doing that but your Woodstock may be a differnt procedure.
  4. Slow1

    Slow1 Minister of Fire

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    Could have something to do with BK using the stainless cat eh?
  5. Backwoods Savage

    Backwoods Savage Minister of Fire

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    I say there is no big deal in waiting at least 10 minutes before engaging the cat. Slow, do you think your wood might be drier than mine? We're burning some 6-7 year old maple, elm, ash and cherry. It is stacked outdoors but under cover of some galvanized roofing. Then we move some wood from the outdoor stack into the carport at the porch so it does not get any rain or snow on it all winter.
  6. learnin to burn

    learnin to burn Feeling the Heat

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    With the metal cat if you have a high moister content in the wood >20% (at least with the BK) you run the risk of warping the cat if you don't have enough flames to burn it off before hitting the cat. I would say if your wood is lighting off within a few seconds of going into the box then you should be fine to engage the cat right away.
  7. Slow1

    Slow1 Minister of Fire

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    Dennis - I seriously doubt my wood can be anywhere near as dry as yours. However it may well be split in smaller pieces which I wonder if that contributes to having such a quick burn.

    I hate seeing the bottom splits turn to coals before I get the cat engaged. I'm also wondering about overheating the inside of the box etc - that inferno has to be seriously hot. My flue temp as measured on surface of the single wall 22" up from the stove goes from under 200f to over 400 in 10 minutes and I KNOW there is lag time in the heat getting through that pipe and the thermometer registering it as with the IR check the temps are even higher, thus I know I'm throwing a lot of flame/heat up the chimney during this time. It all seems like a major waste and I wonder if it could get damaging.

    If the reason for waiting 10 minutes is to drive off moisture it seems clear that the moisture has been driven off well before the 10 minutes, doesn't it?
  8. Wet1

    Wet1 Minister of Fire

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    So are you saying what you are doing is the only way to safely engage the cat?

    FWIW, I don't wait any more than a minute or two before engaging mine (assuming the temp is up). I just wait for some good flames and kick it in.
  9. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Wet, I have no idea where you got that idea and it sounded to me like a slam. I am sorry you felt that way. You can (or anyone can) do what they want to with their stove because it is their stove. If you don't want to bypass the cat at all, that is fine with me. I'll still be waiting the 10-15 minutes before engaging.


    Slow, sometimes we even leave the cat bypassed longer! For example, just a bit ago I came in from cutting wood and the stovetop was below 250. When it got to 250 the flue temperature was still only 300 and I waited probably another 15 minutes before engaging the cat. I had put only 3 small splits in the stove and by the time I engaged the cat the bottom split was almost gone. All went well.
  10. fire_man

    fire_man Minister of Fire

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    I get bummed, too when I see those bottom logs disintegrate before I even get the cat engaged. This year I am burning much dryer wood and I don't wait for 250 on the stovetop to engage anymore. Today I engaged at 200 after running on #2 draft for 10 minutes and the cat lit off really fast. I could tell because the stovetop temp rose quickly.
  11. SolarAndWood

    SolarAndWood Minister of Fire

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    While burning unstackables this fall, I have had a few sizzlers that showed themselves right away because they were in a stove full of dry wood. I don't think it took ten minutes to clear the excess moisture out of them, but I gave it some time with the bypass open to make sure.
  12. Todd

    Todd Minister of Fire

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    During the refueling stage, if the stove’s firebox has an internal temperature below 500 o F., it is best to fire the stove up for 10 to 15 minutes.
    This will provide increased temperature and proper amounts of volatile gases for the catalyst to operate efficiently.

    However, when refueling a hot stove that has an internal temperature above 500 o F., no re-firing is necessary.

    Got this quote from Applied Ceramics. I would only do this if you know your firewood is dry and you have a probe thermometer reading your cat temps. I still wait 10 minutes in bypass mode before engaging even though my wood is 15-20%. I also think if your right at 500 and you reload, the cat will cool down some from opening the door and smothering the fire with more fresh wood. I have cheated a few times and engaged sooner when I have a huge coal bed and stove top of 300 or so.
  13. Rockey

    Rockey Minister of Fire

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    I never wait when I throw dry wood in. I dont see any reason to let the heat go right up the flue instead of heating my home. No negative effects on the cat so far, been burning this way for 4 years now.
  14. rickw

    rickw New Member

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    Well, I don't wait very long if the stove is hot - maybe a few minutes. I'm sure this will affect the useful life of the cat but there is no sign of crumbling/cracking/degradation yet (on the 2nd season).
  15. Lanningjw

    Lanningjw Feeling the Heat

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    I get bummed, too when I see those bottom logs disintegrate before I even get the cat engaged. This year I am burning much dryer wood and I don’t wait for 250 on the stovetop to engage anymore. Today I engaged at 200 after running on #2 draft for 10 minutes and the cat lit off really fast. I could tell because the stovetop temp rose quickly.

    Where is a #2 draft setting on your temp control? Is it a medium setting or lower?
  16. Slow1

    Slow1 Minister of Fire

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    Fireview has a slider air control that is marked from 0-4 with about 3/4" between each marking. The difference in amount of air is pretty dramatic with even a slight adjustment so that 1/4 difference between .5 and .75 does change things. Opening to 4 looks about like running my old VC with the ash drawer open a bit. I have not had to open my door to fan the flames and in fact I generally only open the draft to about 3 on reloads as more than that and the ash if flying about in the box quite a bit.
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