Insulation

[benny8]

Question regarding pouring loose vermiculite into enclosure. I can get a bag of vermiculite that is 4 cubic foot. If my enclosure is 4 feet wide by 4 feet long and 4 feet high, I should only need one bag, is this correct? What are the recomendations for using loose vermiculite in an enclosure? I can not get the ceramic blanket locally and do not wish to pay the high price of shipping. Your guidance is appreciated.

[Les]

Re: Insulation

Question regarding pouring loose vermiculite into enclosure. I can get a bag of vermiculite that is 4 cubic foot. If my enclosure is 4 feet wide by 4 feet long and 4 feet high, I should only need one bag, is this correct? What are the recomendations for using loose vermiculite in an enclosure? I can not get the ceramic blanket locally and do not wish to pay the high price of shipping. Your guidance is appreciated.

4x4x4 is 64 cubic ft. You need 16 bags...

[UtahBeehiver]

Re: Insulation

Les is correct on a pure volume of a cube, if you factor out the space of your oven it will be less volume than a pure cube. The volume of a 1/2 sphere is 2 times pi times radius squared. So if you use the cube volume and subtract the 1/2 of a sphere volume and add a fudge amount there you go.

[Les]

Re: Insulation

Les is correct on a pure volume of a cube, if you factor out the space of your oven it will be less volume than a pure cube. The volume of a 1/2 sphere is 2 times pi times radius squared. So if you use the cube volume and subtract the 1/2 of a sphere volume and add a fudge amount there you go.

You are correct Russell - my mind was multi-plexing between another task and spaced that out... Oh yea, I screwed the other task up as well - not a good Monday morning start...

[UtahBeehiver]

Re: Insulation

Les,

Every day is like that for me not just Mondays................

[benny8]

Re: Insulation

4x4x4 is 64 cubic ft. You need 16 bags...

Oh my god-I just read what I wrote earlier today. DUH!!!!!!! It has definitely been a MONDAY. Wow, do I feel stupid. Ok, I'm good now. If I want to insulate with loose vermiculite, will this be sufficient if I fill the enclosure? Thanks for the replies guys.

[UtahBeehiver]

Re: Insulation

That's okay, we all get brain cramps once in a while.

BTW R value for loose fill vermiculite is about 2.0 per inch thickness vs CF super wool being about 7.0 so take it for what it is worth. So if your oven dome gets near your enclosure you may want to look at these areas closely.

[Les]

Re: Insulation

Oh my god-I just read what I wrote earlier today. DUH!!!!!!! It has definitely been a MONDAY. Wow, do I feel stupid. Ok, I'm good now. If I want to insulate with loose vermiculite, will this be sufficient if I fill the enclosure? Thanks for the replies guys.

Benny - how big is your oven? I went with the blanket but I would think you want at least 4 inches of loose vermiculite on the sides. You should be very well insulated on the top.

[benny8]

Re: Insulation

Benny - how big is your oven? I went with the blanket but I would think you want at least 4 inches of loose vermiculite on the sides. You should be very well insulated on the top.

My oven will be 30" inside diameter. It will be a cast oven with 2" walls. How many rolls of the CF blanket would I need to achieve the 4" recommended? I see it 50sf rolls-2'x25'x1"-would 1 roll do 4 layers for a total of 4"?Thanks again for the replies.

[Les]

Re: Insulation

That's going to give you 7 inches of insulation on the sides - no need for the blanket. The vermiculite will be less expensive and a whole lot easier to work with.

[rsandler]

Re: Insulation

Les is correct on a pure volume of a cube, if you factor out the space of your oven it will be less volume than a pure cube. The volume of a 1/2 sphere is 2 times pi times radius squared. So if you use the cube volume and subtract the 1/2 of a sphere volume and add a fudge amount there you go.

Actually, 2 pi times the radius squared is surface area of a half sphere (another useful quantity for ovens), not volume. Volume is 2/3 pi times radius cubed, or in your case 17x17x17x0.66xpi = ~10300 cubic inches, about 6 cubic feet. Even if your enclosure goes up 48 inches, filling the whole box would be overkill--getting up to a height of 24" would give you a 7" layer. So you want 4x4x2 - 6 = 26 cubic feet, or 7 bags.

If you do the surface area calculation, it appears that your dome will be roughly 12.5 square feet, and in principle one roll of blanket will stretch to a 4" layer.

[benny8]

Re: Insulation

Thanks guys-really appreciate the info. Looks like I will be going with the loose vermiculite due to availability, price, shipping, and not having to monkey screw with blanket. Hoping to have my project completed before Memorial Day weekend.

[UtahBeehiver]

Re: Insulation

I did make an error, you are right, this was the formula I was using to determine the square inch surface area of my dome for calculating the amount of blanket coverage. So we all get a brain cramp once in while......

[david s]

Re: Insulation

Sphere volume is 4/3 phi rxrxr. Halve that for a hemisphere and deduct it from the enclosure volume (length x height x depth)

You can fill the corners with something cheaper like free fibreglass off cuts because you don't need the insulation so thick in the corners anyway.