Need advise on final arch build arch board and grate details

[DoubleBrookMaple]

My 2X4 is nearly complete. Need doors fabricated and installed, and blower installed.

In the pictures you will see I have arch board and brick installed nearly to top of the firebox.

1. Top of Fire box.

Options:

A. Leave as is with 1 inch board only at top couple inches
B. Cut back angle iron approx 3/4" for more pan exposure.
C. Install second layer of 1/2 of arch board as shown in picture to flush with 2" angle

I tend to like option B

2. Grate height

Options:

A. Recess the grate 2-4 inches below fire box floor
B. Make grate flush with floor

I tend to like option A.

Thanks in advance for any and all input from all, and thanks for being here. The hours and hours of reading the forum is paying off.

Eric862286238624

[lpakiz]

Issue #1. I vote B. Trim angle iron back to even with first layer of arch board, for exactly the reason you said.
Issue #2. I vote B. Only if your door is at maximum dimensions already. I doubt a door is ever to big on a 2 foot wide rig.
Looks good! Be sure there is no metal exposed to flame, except bottom of sap-filled pan. The flames will devour any exposed metal. Either arch board, ceramic blanket, brick or castable or poured refractory cement. Bricks only necessary in firebox area, to protect insulation from damage by wood.

[DoubleBrookMaple]

Be sure there is no metal exposed to flame, except bottom of sap-filled pan. The flames will devour any exposed metal. Either arch board, ceramic blanket, brick or castable or poured refractory cement.

So, I should build my door so that ceramic blanket will go into the opening and somewhat cover the metal you see in this picture?
I planned on a 2" deep 2" oversize door with ceramic blanket close flush (compressed), and seal with outside of door frame.

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[lpakiz]

That is a nice looking door frame! On mine, I insulated just the sides of the firebox area. The door frame is hollow, with forced air circulating thru it. I used thin fire bricks, standing on end, to line the inside side-walls of the door frame. I installed the main-side bricks to reinforce and butt against the door frame bricks, because that is where most of the abuse from loading wood will occur. I'm afraid this process will make your door even smaller. I doubt that just blanket will survive very long loading wood thru it.

Top and bottom, I built forms out of light plywood and mixed up refractory cement (like Quikcrete) and poured the upper and lower sills. I welded some short 5/16 bolts inside the door frame, nose first, to give the refractory more to grab onto. Refractory is probably 2 inches thick, but I had to protect air nozzles there also. Whatever metal of the air nozzles that extended past the refractory is now burned away. So far, (one year) the refractory and bricks look perfect. I see what you have built so far and I'm pretty sure you are capable of this. I'm concerned that the doorway will end up too small, but you must protect that steel. Perhaps consider scrapping the door fram and liner and start over, making the door frame max size possible.
Your door idea itself is great-the ceramic blanket will compress against the door liner ledges things and seal really nice.

[MN Jake]

When I rebuilt my 2x4 into a 2x10 I welded in a continuous 10' 2x2 3/16 for each top rail and found out it was bowing up in the middle during boiling. Would it be a safe bet that the top (pan contacting surface) of the angle iron be trimmed back like described in this thread?

[lpakiz]

Jake,
Do you have that iron insulated with arch board or blanket, or at least protected with brick? My top bricks are 1 1/4 thick "splits" that end about an inch under the angle iron. I tuck-pointed refractory (or high temp mortar)? into the remaining void, so the 2 X 3 X 3/16 angle iron never sees the fire. Well, maybe the 3/16 thickness of the iron, but that's all. Farther back, out of the firebox area, I have 2 layers of 1 inch blanket on the ramp and on the ramp sides, all the way to the back. No bricks there.

[DoubleBrookMaple]

I'll shield the door frame as best I can for this season, and do something permanent in the off season. I am going to leave the top rails alone, at least for now, and need to decide on the grate height still. I mounted my blower motor today.
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[MN Jake]

Jake,
Do you have that iron insulated with arch board or blanket, or at least protected with brick? My top bricks are 1 1/4 thick "splits" that end about an inch under the angle iron. I tuck-pointed refractory (or high temp mortar)? into the remaining void, so the 2 X 3 X 3/16 angle iron never sees the fire. Well, maybe the 3/16 thickness of the iron, but that's all. Farther back, out of the firebox area, I have 2 layers of 1 inch blanket on the ramp and on the ramp sides, all the way to the back. No bricks there.
I do have the 1" gap from firebrick to steel with 3/4 ceramic board all the way up. So I do have about 1 1/4" of steel showing to about 5' back, then 3" mineral wool on bottom and sides from there and back tucked tight to the steels edge.

[lpakiz]

Jake,
Could you mud that in with firebrick mortar? Taper it from the top edge of the brick to the front edge of the angle iron. Or could you tuck it full of blanket or strips of arch board? Near the top there, you will never damage the insulation with wood.
Does the top rail return to straight when it cools off?
Do you think if you get that rail protected, it won't bow from the heat?
If you remodel the door frame in the off-season, then whatever damage the flames do this season won't matter.

[MN Jake]

Ipakiz, I'm not so worried about flames destroying the steel as I am about the pans tilting slightly. The rear of the front pan and the front of the rear pan get pushed up when it's going strong. I may be running 1" in the very front and back but where they meet in the middle it's roughly 1/2" deep. When I read the post about shaving the angle iron I thought that might help. I can weld and tinker but haven't dealt with steel in a heat situation.
However, it may be nice to protect as much steel as possible to not have to add new steel as it wears.

[MN Jake]

And also open the interior space for flame to pan. Last year I could not open and put wood in without a welding glove, and sure as heck couldn't look at the firebox.

[lpakiz]

Last year I could not open and put wood in without a welding glove, and sure as heck couldn't look at the firebox.[/QUOTE]
Yeah, welcome to the club. Sometimes we even used a face mask, the heat is so intense. We made a "staging rack" for wood. It separated the wood into 3 double handful bundles. We learned to use the bundle of wood as a heat shield to hide behind as we loaded the next charge. Definitely gotta get the wood in fast and get the door shut.

[DoubleBrookMaple]

Thanks for your replies....

I finished today!

I decided to keep the top rail intact for now. Did not want to cut.
I decided on sacrificial archboard for the door.
Installed door handle switch to shut off blower when lever turned.
OMG... My door should be cool... 2 inches of blanket, 2 inches of archboard!

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[DoubleBrookMaple]

Thanks for your replies....



I decided to keep the top rail intact for now. Did not want to cut.



Well... Test boil with water, and a large area all around the perimeter of the pan does not boil!

I am going out right now, and cut the rail back. I will mark it with my yellow ink marker, and leave 1/2" +or- a bit.

[DoubleBrookMaple]

Here is the area covered by the 2 inch angle iron rail and arch board, my cut with arch board removed from top, and a view after the pan put on again. I gained close to 120 square inches. Three hours work, but will save me much more than that over the course of the season.

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