FB insulating blanket alternatives?

[james]

Re: FB insulating blanket alternatives?

The cost of blanket insulation in the US has come down in price to where it is very close to the cost of vermiculite. And it is so much easier to use and it is so much more efficient.

FB will be going 100% solid state (board and blanket) insulation in the near future.
James

[kebwi]

Re: FB insulating blanket alternatives?

Hmmm, just to be specific about it, adhering strictly to the Pompeii directions for a 36" oven, page 59, dome insulation options are...

Either:
1 blanket = $75 + $30 shipping = $100
+ 3 bags verm/perl ($15 apc, obtained locally) = $45
+ small amount of Portland (dome, not enclosure) = negligable
= $145
or:
6 bags verm/perl = $90
+ some Portland (negiglable?!!)
= $90
or:
2 blankets = $150 + $30 = $180

Okay, it's within a factor of two cost, only 1.5 times if you combine the methods. However, it is worth noting that other folks in this thread are considering going beyond the Pompeii directions, such as three blankets, no verm/perl. Once you start lobbing on additional blankets, the difference in cost between the two methods starts growing rapidly.

Just saying...

[redmen4]

Re: FB insulating blanket alternatives?

I agree on the cost. Unfortunately my space is very limited and will have to go the three blanket route and the extra cost. Also, everyone says do not skimp on the insulation.

JQ

[lwood]

Re: FB insulating blanket alternatives?

I'm interested in the perlite/cement vs. blanket question as well. I'm going to have a tough time getting the fiber blanket here in the Philippines. How much more perlcrete should I add to replace the fiber blanket? Or are there other alternatives?

[david s]

Re: FB insulating blanket alternatives?

There is a comparison somewhere on the forum, but I think you need to go 50% thicker for the same insulation value, but remember that the more cement you add to the vermiculite/perlite insulation the more you reduce its insulating capacity.

[RTflorida]

Re: FB insulating blanket alternatives?

The blanket is at least twice as efficient as perlcrete or vermicrete. I used both, as many do. 1 layer of 1" blanket and 3 inches of perlcrete is sufficient. If using perlcrete alone, as LEAST 4", preferably 5-6".
Personally, I had already purchased 3 bags of vermiculite and 3 bags of perlite and intended to skip the blanket.....then I found a fantastic deal on ebay for a 25 sq. ft roll of 2" #8 Insulfrax blanket, so I proceeded with 1 layer of the 2" blanket and 2 1/2" of perlcrete. I've been totally happy with heat ups as well as retained heating.

RT

[kebwi]

Re: FB insulating blanket alternatives?

So, ceramic fiber blanket seems to be pretty standardized. One parameter is the density in pounds for cubic foot, which is usually four, six, or eight. I believe FB's is eight. What are the performance differences between the three? Why would you want four, six, or eight for a particular application? As far as I can tell, they all have the same max temperature tolerance. Do the different densities offer varying thermal insulation for the same overall blanket thickness? If so, are the less dense or more dense blankets more insulative, i.e., better for brick ovens?

[david s]

Re: FB insulating blanket alternatives?

QUOTE=Yahoo-Archive;267]The rule of thumb is 1" blanket and 4" vermiculite. I had an insulation engineer run a test, and conclude that the blanket replaces 2" of loose vermiculite. We had them run a simulation where they added 1" of insulfrax, and reduced 1" of vermiculite. 1":4", 2":3", etc. over a 24 hour 1000F exposure. The outer face tested consistently dropped by adding 1" more insulfrax and 1" less vermiculite.



1" Insulfrax Blanket 6#, 4" Vermiculite 1000F** 172F

2" Insulfrax Blanket 6#, 3" Vermiculite 1000F** 161F

3" Insulfrax Blanket 6#, 2" Vermiculite 1000F** 151F

4" Insulfrax Blanket 6#, 1" Vermiculite 1000F** 142F

5" Insulfrax Blanket 6# ******* 1000F** 135F


Test shows loose vermiculite 50% the efficiency of blanket. Cement added to vermiculite, not shown in test, will further reduce the efficiency so use as little as possible.

[shuboyje]

Re: FB insulating blanket alternatives?

Just to add a bit of info I didn't see in this thread(sorry if I missed it).

I recently finished my oven and have now fired it twice post curing. I used 6 inches of loose fill insulation around the entire oven and have yet to measure a temperature above ambient on the outside even with the oven at 1000F. The obvious downside of this method is the foot of space it takes around the oven.

[philiph4@ameritech.net]

Re: FB insulating blanket alternatives?

I have 1" kao wool blanket. It should be enough foe a 2 inch layer. Is this enough insulation?