Insulated door design...

[Aussie Pete]

Re: Insulated door design...

geeezz..i got a little confused then, when chip posted up after my post, i had a look at the pics he put up, and thought...."thats not your door you posted earlier Russel". Then i realised it wasn't your post Russell....d'oh.
I like the idea of the cladding on the front, it seems to finish off the door nicely, i might possibly use something like Merbau (not sure), get that nice dark red colour. I'm trying to think of a way to make the door so theres no heat transfer through at all (as in no bolts through the plate), can be done i'm sure, just have to think of an idea for design.
if i was to use the wood cladding on the front, what glue or silicone sealer would hold it on ok....(liquid nails be any good), after all, hopefully there wont be much heat after the insulation....right?.
I wont be making for a while yet, just trying to get ideas worked out, so i know what to do when i come to it.

[mrchipster]

Re: Insulated door design...

Pete and Russell,

Sorry about creating confusion by jumping in on your post.....

I have an idea for and thermally isolated door.

The concept is quite simple.

The door is made up of 2 layers of ceramic board encapsulated inside of some type of metal sheathing ideally this would be a reasonably light gauge stainless. Each layer of the ceramic board would be attached to the front or back respective plate with bolts with washers large enough not to pull through the expanded metal internal sheet that is between the 2 layers of ceramic board.

This would allow minimal heat transfer due to the expanded metal yet strength because of the bolt ties to the inside and outside.

An additional level of safety from burning of the decorative outside layer could be provided by mounting the decorative layer to the outside sheet by having small risers preventing direct contact with the potentially hot outside sheet. I would make the decorative outer layer (think wood) a little smaller than the sheet that is directly in contact with the oven as I had one door burn up because it was exposed to the hot gasses escaping the oven at the top. Making the decorative door a half inch or so smaller would not take away from the way it looks because most of the time the door will be inserted into the flue opening and deep into the tunnel.

The piece of metal that wraps around the edges of the ceramic board could maintain a small gap between the outside sheet and the wrapper sheet to prevent any thermal connectivity from the interior the oven to the outside. This would also be the location where a glass rope could be placed to better seal the oven.

As you can see from the drawing the bolts are offset from each other and because there are 2 layers of insulation heat transfer would be minimal.

Other materials could be used in place of the expanded metal but I believe this would be strong and still conduct a minimal amount of heat.

The expanded metal would not go out to the edge of the door but be fully encapsulated between 2 layers of ceramic board. The ceramic board could be of any thickness from half-inch all the way up to 2 inch thick depending upon the insulation needs of your door and the 2 layers could be of different thickness. If so desired.

Chip

[Aussie Pete]

Re: Insulated door design...

thanks Chip, think i've got the idea.

[Dino_Pizza]

Re: Insulated door design...

Hi Chip,
I have a similar drawing as you with the same idea. I've yet to make my door but that is what I had planned on.

I have left over FB blanket and it compresses slightly so 2 isolated layers will work and I was thinking that since there is less heat transfer, I can bolt (or even glue) a thin wood "facade" to the outside of the metal door and even replace it every few years if needed.

This is a good thread, thanks Russell and Chip for some fine ideas on door building, possibly the hardest part of the wfo process at least for me

I've been using a temporary door made of 2 pieces of duroc (cement board) with oven mortar inside it and it's HEAVY and of coarse brittle and chipping like crazy so I don't recommend EVER doing it except as a quicky door after you've just finished your oven and you have scraps laying around.

[Laku]

Re: Insulated door design...

Here's my version of the door. Idea being that inside and outside surfaces have very little contact area with each other. Kind of a heat break build into it.

http://www.fornobravo.com/forum/44/c...tml#post138419

What I haven't drawn in the picture is a plywood cover to attach the decorating wood to at the front. Between the plywood and ssteel front there's also glassfiber rope to keep them appart.

[Dino_Pizza]

Re: Insulated door design...

Very nice design, I may implement it instead. The only direct heat transfer would be through the bolts and minor radiation.

It all kind of depends (for me) on how heavy of a gauge sheet metal I can pick up at the local 'big-box' hardware stores that I can still successfully cut with tin-snips. If the sheet metal will be thin, then maybe the rigidity of 3 sheets may work better for me; if it's heavier gauge, I like you design better.

thanks, Dino

[mrchipster]

Re: Insulated door design...

Hi Chip,
I have a similar drawing as you with the same idea. I've yet to make my door but that is what I had planned on.

The only thing I would change on your design is the internal layer could be metal lathe and not a solid piece of sheet metal. Removing extra material on that internal piece would also aid in reducing heat transfer.

Chip

[mrchipster]

Re: Insulated door design...

Very nice design, I may implement it instead. The only direct heat transfer would be through the bolts and minor radiation.

It all kind of depends (for me) on how heavy of a gauge sheet metal I can pick up at the local 'big-box' hardware stores that I can still successfully cut with tin-snips. If the sheet metal will be thin, then maybe the rigidity of 3 sheets may work better for me; if it's heavier gauge, I like you design better.

thanks, Dino

I found a 4 inch angle grinder with a thin curf metal wheel 1/16 inch. Works great for cutting sheet goods.

Chip