Grandpa Baffle Question

[Johnny iuzzini]

Can't be any simpler! It will be interesting to see if that plate stays flat for you or not.

pen

Hi Pen

I have a grandpa bicentennial 76 and was trying to see your pics from the baffle you made in old posts but the links no longer works? Any ideas how to retrieve it. Also trying to get a hold of a copy of the original owners manual. Would be cool to have.

thanks in advance

Johnny

 

[coaly]

Hi Pen
I have a grandpa bicentennial 76 and was trying to see your pics from the baffle you made in old posts but the links no longer works? Any ideas how to retrieve it. Also trying to get a hold of a copy of the original owners manual. Would be cool to have.
thanks in advance
Johnny

Owners manuals are in the sticky section at top. You would use this one, it is printable;
Fisher_Manual.pdf

 

[pen]

Hi Pen

I have a grandpa bicentennial 76 and was trying to see your pics from the baffle you made in old posts but the links no longer works? Any ideas how to retrieve it. Also trying to get a hold of a copy of the original owners manual. Would be cool to have.

thanks in advance

Johnny

I'm guessing those pictures were on photobucket and are lost. I essentially made a table out of angle iron, and set firebrick into the angle iron as the "table top" or top of the baffle. I let the legs sit right on the top of the firebrick on the sides. If I recall, I made the opening left in front of the baffle, just a few sq inches more than the sq inches of an 8 in pipe, 55sq inches comes to mind.

pen

 

[Johnny iuzzini]

I'm guessing those pictures were on photobucket and are lost. I essentially made a table out of angle iron, and set firebrick into the angle iron as the "table top" or top of the baffle. I let the legs sit right on the top of the firebrick on the sides. If I recall, I made the opening left in front of the baffle, just a few sq inches more than the sq inches of an 8 in pipe, 55sq inches comes to mind.

pen

thanks for the info.

 

[Johnny iuzzini]

Owners manuals are in the sticky section at top. You would use this one, it is printable;
Fisher_Manual.pdf

Many thanks- still figuring out the site

 

[Johnny iuzzini]

I'm guessing those pictures were on photobucket and are lost. I essentially made a table out of angle iron, and set firebrick into the angle iron as the "table top" or top of the baffle. I let the legs sit right on the top of the firebrick on the sides. If I recall, I made the opening left in front of the baffle, just a few sq inches more than the sq inches of an 8 in pipe, 55sq inches comes to mind.

pen

 

[Johnny iuzzini]

Owners manuals are in the sticky section at top. You would use this one, it is printable;
Fisher_Manual.pdf

I just read through some of your older posts as I’m trying to figure out the best way to make the baffle for my grandpa- some of the posts say to pitch it at 45 degrees but when I look at your pics it looks level? What am I not understanding here?

 

[coaly]

The camera is pointing upwards at about a 45* angle. The baffle is not horizontal .
Cut a piece of cardboard to sit on the rear brick retainers, angle upward at front toward lower bend in top. Make opening no smaller than square inch opening of chimney flue. This gives you baffle plate size.

 

[Johnny iuzzini]

The camera is pointing upwards at about a 45* angle. The baffle is not horizontal .
Cut a piece of cardboard to sit on the rear brick retainers, angle upward at front toward lower bend in top. Make opening no smaller than square inch opening of chimney flue. This gives you baffle plate size.

Oh I see now, did you weld that angle bar into place in the stove?
When you say "make opening no smaller than square inch of chimney flue",
If I have an 8" diameter flue

PI/4 * Diameter^2
(3.1416/4) * 8 * 8 = 0.7854 * 64 = 50.27 square inches

So leave 50.25" of space between the end of the baffle and the stove wall?

is there a reason you brought your sides in on each side? Better circulation?

I saw other posts at some point where people were saying to bend lips into the metal? For what purpose?

 

[coaly]

That is a factory baffle in a Goldilocks, same width as Grandma.
They cut 3 X 3 inch square notches in the front of factory baffle for circulation and prevent stagnation of movement in the corners.
8 inch round flue; radius (half the diameter) squared (times itself) X pi or 3.14.
4 X 4 = 16 X 3.14 = 50.24
That is the square inch area of 8 inch square opening.
That is the minimum opening the smoke needs to go through. So length X width of opening (smoke space) must be that minimum size.

Bending a lip will strengthen the plate from warping. That factory plate is 5/16 thick and as straight as the day it was installed.
I gave you your own thread to continue with any questions here.

 

[Johnny iuzzini]

That is a factory baffle in a Goldilocks, same width as Grandma.
They cut 3 X 3 inch square notches in the front of factory baffle for circulation and prevent stagnation of movement in the corners.
8 inch round flue; radius (half the diameter) squared (times itself) X pi or 3.14.
4 X 4 = 16 X 3.14 = 50.24
That is the square inch area of 8 inch square opening.
That is the minimum opening the smoke needs to go through. So length X width of opening (smoke space) must be that minimum size.

Bending a lip will strengthen the plate from warping. That factory plate is 5/16 thick and as straight as the day it was installed.
I gave you your own thread to continue with any questions here.

Thanks for the info and for kicking me out of the other thread!

 

[coaly]

Yeah, this way you're question is searchable pertaining to your model stove.

Fisher welded the angle iron supports in place. I prefer to set the baffle on bricks on their sides so they can be cut or shimmed to the proper height to adjust the opening and angle. They had to be very conservative with baffle size not knowing how well each chimney would draft, or the diameter of existing chimneys that would be used. Connecting your own, you can set it to the minimum, and if you have any smoke roll in when opening doors, drop the plate in he front, opening the space to allow more heat up until you get it just right. The Baffle thread was written for smaller baffles in the single door stoves, so it will be more costly for a wide double door stove. Fisher installed factory baffles in the double door Fireplace Series only, after 1980. They were much smaller since many were connected to fireplace chimneys much larger in diameter, requiring more heat.

 

[Johnny iuzzini]

Yeah, this way you're question is searchable pertaining to your model stove.

Fisher welded the angle iron supports in place. I prefer to set the baffle on bricks on their sides so they can be cut or shimmed to the proper height to adjust the opening and angle. They had to be very conservative with baffle size not knowing how well each chimney would draft, or the diameter of existing chimneys that would be used. Connecting your own, you can set it to the minimum, and if you have any smoke roll in when opening doors, drop the plate in he front, opening the space to allow more heat up until you get it just right. The Baffle thread was written for smaller baffles in the single door stoves, so it will be more costly for a wide double door stove. Fisher installed factory baffles in the double door Fireplace Series only, after 1980. They were much smaller since many were connected to fireplace chimneys much larger in diameter, requiring more heat.

Hi Coaly,
So I am back at my cabin this weekend and want to get this all sorted out.
you had said "Cut a piece of cardboard to sit on the rear brick retainers, angle upward at front toward lower bend in top. Make opening no smaller than square inch opening of chimney flue. This gives you baffle plate size."

I assume you meant on top of the new additional bricks on each side first right before doing the cardboard? What holds the additional bricks in place, the weight of the baffle?

So here it is mocked up- I cut the wood 9.5" (same size as the bricks i'll buy). i cut 2 pieces of cardboard to measure down 2" from the top of the stove for airflow based on the 8" pipe/52" sq inch. The cardboard ended up being 26.5" wide (27" stove width) x 12". Im left with about about inch between the edge of the baffle and the top part of the curved front. Should i cut this down to 11" or less to be sure I have the same 2" airflow space in that area as well?

BTW i got a copy of the woodburners encyclopedia and am realizing so much of what i was taught as a kid is completely wrong.

 

[coaly]

It can set right on the existing brick retainers at rear. No other bricks across back necessary.
Point the baffle at the lower bend, keeping the open area the same as your outlet and flue square inch area so the area the exhaust travels is no smaller than the venting square inch area. That assures no restriction. Raising it a touch will increase the open area if needed and the steeper angle increases velocity of rising gasses. It doesn't take much to make a big difference.

I sat my first baffle on side bricks like you pictured when trying and adjusting it. It sat on them ok, but I was afraid I would sooner or later knock one down, letting baffle crash, so I later welded angle iron to the baffle plate to keep the bricks against the sides from falling. You can bolt angle iron to the plate instead to keep bricks against sidewalls. I used 1 1/2 inch angle iron just like the brick retainers.

Upside-down baffle plate with angle iron.

Yes, that Encyclopedia has a LOT of information. Things we were taught weren't always wrong, but the reasoning behind why things were done the way they were wasn't always correct.

 

[Johnny iuzzini]

It can set right on the existing brick retainers at rear. No other bricks across back necessary.
Point the baffle at the lower bend, keeping the open area the same as your outlet and flue square inch area so the area the exhaust travels is no smaller than the venting square inch area. That assures no restriction. Raising it a touch will increase the open area if needed and the steeper angle increases velocity of rising gasses. It doesn't take much to make a big difference.

I sat my first baffle on side bricks like you pictured when trying and adjusting it. It sat on them ok, but I was afraid I would sooner or later knock one down, letting baffle crash, so I later welded angle iron to the baffle plate to keep the bricks against the sides from falling. You can bolt angle iron to the plate instead to keep bricks against sidewalls. I used 1 1/2 inch angle iron just like the brick retainers.

View attachment 255496 Upside-down baffle plate with angle iron.

Yes, that Encyclopedia has a LOT of information. Things we were taught weren't always wrong, but the reasoning behind why things were done the way they were wasn't always correct.

Ahh i see what you mean and I did place it on the back originally but felt it cut into the actual fire area too much. A close friend has a metal shop so he will cut/weld me whatever I need. I like the idea of using the angle iron. Did you use 1.5" flush to the edge? I may do the notched corners as well like your setup direct from fisher.

It's 8 degrees outside right now so I have the stove jammin. Ill make a new template when I let it die out in a few days.

Also- I bought this condar 15 years ago and have loved it but now that I have been reading through the book I'm not sure I have been using it 100% correctly. I was always told to open the pipe flue damper everytime you open the door to load and then keep it just opened slightly to slow the wood burning down and only used the candar to adjust temp. No I am wondering if I should be closing it some in the beginning to build up the fire when lighting.

 

[coaly]

You will get so much more heat out of it you won't need to load as heavy. It doesn't affect how much you load since you don't load against the outlet anyway. (or shouldn't be)

I put the angle iron to the edge of plate. If you wedge a piece of long wood that only fits diagonally in the stove between the bricks to hold them in place against the sides, you can set the plate on top of them, push the plate to the rear and let it drop in place. Remove the wood. The only way baffle is coming out is by sliding it forward and tilting level to remove.

Open damper when opening doors. Keep it open with air inlets open until flaming good.
The only time I partially close flue damper when starting is if a lot of kindling or cardboard burns fast enough to roar up the stack. I close it slowly until the roar stops. You don't want all the heat rushing up the stack without heating the larger pieces in the firebox. But you don't want to close it enough to slow the flow, depriving it of the needed oxygen to get it going. The flue damper is a chimney control that reduces an over drafting chimney by slowing velocity. (slowing velocity decreases net draft, slowing the incoming air. So it controls the chimney, which affects the stove) When up to temp, you may be able to keep flue damper open and control flow with intake dampers. Only if it takes off as intake dampers are opened slightly more than about 1 turn would you need to slow the chimney.

You'll find adding the baffle makes it much more controllable. The high heat swings and high exhaust temps become much more steady with less control changes needed.

 

[Johnny iuzzini]

You will get so much more heat out of it you won't need to load as heavy. It doesn't affect how much you load since you don't load against the outlet anyway. (or shouldn't be)

I put the angle iron to the edge of plate. If you wedge a piece of long wood that only fits diagonally in the stove between the bricks to hold them in place against the sides, you can set the plate on top of them, push the plate to the rear and let it drop in place. Remove the wood. The only way baffle is coming out is by sliding it forward and tilting level to remove.

Open damper when opening doors. Keep it open with air inlets open until flaming good.
The only time I partially close flue damper when starting is if a lot of kindling or cardboard burns fast enough to roar up the stack. I close it slowly until the roar stops. You don't want all the heat rushing up the stack without heating the larger pieces in the firebox. But you don't want to close it enough to slow the flow, depriving it of the needed oxygen to get it going. The flue damper is a chimney control that reduces an over drafting chimney by slowing velocity. (slowing velocity decreases net draft, slowing the incoming air. So it controls the chimney, which affects the stove) When up to temp, you may be able to keep flue damper open and control flow with intake dampers. Only if it takes off as intake dampers are opened slightly more than about 1 turn would you need to slow the chimney.

You'll find adding the baffle makes it much more controllable. The high heat swings and high exhaust temps become much more steady with less control changes needed.

ok so I removed the rear brick and using wood as dummies for firebricks I cut a new cardboard to the largest that I Could fit in without bending etc. as I let it slide down to the back the top is actually leaning against the overhead pipe. I can’t raise it in the back without trimming the bricks. So wondering if I should make it smaller or just trim the bricks. Size of damper is currently 26.5 x 14.
I could also notch the corners like yours. 2”x 2”

 

[Todd67]

Those tall boards you are using on the sides? Turn them horizontal and it will correct your baffle plate angle. I just put a baffle plate in my neighbor's Grandpa Bear and it works great.

You might have to cut the firebrick in half to lay it sideways.

 

[Johnny iuzzini]

Those tall boards you are using on the sides? Turn them horizontal and it will correct your baffle plate angle. I just put a baffle plate in my neighbor's Grandpa Bear and it works great.

You might have to cut the firebrick in half to lay it sideways.

What size baffle did you put in?

 

[coaly]

I like to angle the brick corner so the plate sits on the angled edge. They cut as easy as the board.
If you don't have a masonry blade, cut one brick in half with chisel by scoring like you would a cement block or brick. The rough cut doesn't matter when used on its side.

 

[Todd67]

What size baffle did you put in?

26" x 13"