Additional insulation for modular ovens

[GreenBldr]

I've noticed where a number of users swear by the practice of adding vermiculite above the refractory blanket in their ovens, but the instruction set on my Casa 2G90 oven indicates there must be air directly above the 2-3" of dome insulation.

I have a terrible desire to add mineral wool (Roxul) as additional insulation over the factory-supplied blanket.

In my case, the (indoors) oven sits inside a chimney chase with insulated studwalls and lined with cement board.

Has anyone increased the oven insulation with mineral wool batts and what would the downside be?

[SCChris]

Re: Additional insulation for modular ovens

I don't see why additional insulation would be a problem, have you asked / called Forno Bravo to ask?

Chris

[GreenBldr]

Re: Additional insulation for modular ovens

I think it messes with the UL listing or something. There is a data plate with the oven that says the same thing.

[Tscarborough]

Re: Additional insulation for modular ovens

I think you may be misunderstanding what it is saying. You must have 2" airspace to flammable materials, but the distance is the important thing, and the insulation is not flammable (I would hope).

[GreenBldr]

Re: Additional insulation for modular ovens

Well, misunderstanding is always a possibility, but the data plate says to not add insulation, and it even shows a diagram of the oven with a 1" air gap to anything. I'm firing it for the first time with the refractory blanket installed. I've got the temperature at the outside top of the dome up to 400 degrees (remote temperature probe) and there is NO detectable heat coming through the blanket layers.

[Tscarborough]

Re: Additional insulation for modular ovens

Code says 2" to combustible, but I would call Forno and confirm what they suggest.

[GreenBldr]

Re: Additional insulation for modular ovens

Code is one thing, but product parameters and certification are generally the bailiwick of the manufacturer. Let me quote the manufacturer's data plate for this particular oven.

"Maintain 1" clearance (airspace) on all sides and 14" on top..."
"Do not fill required air space with insulation or other materials"

The question has nothing to do with combustibles, but whether or not it is prudent to put more insulation on top of the factory-supplied ceramic blanket.

In pursuit of more data, I fired my oven for the second time with the ceramic insulation installed. After 10 hours of fire, the interior was 950F and the sensor placed outside the top of the dome, but under the ceramic blanket read 770F. Plenty hot. Temperature readings outside the blanket only ran about 110-120F. That's not gonna even faze the mineral wool which goes over 2000F. I'd really like to get this oven better insulated so as to hold the heat longer, or even to reduce the amount of wood needed to fire it.

[WJW]

Re: Additional insulation for modular ovens

Without regard to what it says...that doesn't make sense to me. Have you called FB as suggested?

Bill

[Tscarborough]

Re: Additional insulation for modular ovens

Actually, Green, you are wrong about that in this instance, no matter what the manufacturer recommends, code will take precedence.

[GreenBldr]

Re: Additional insulation for modular ovens

There is nothing to be wrong about. I did not claim that either code or UL listing or manufacturer's recommendations took any kind of precedence over any other. This is a question about what is prudent.

[GreenBldr]

Re: Additional insulation for modular ovens

..that doesn't make sense to me

I think that's why I have a question about it.

I'm sorry. I was under the impression that the FB rep cruises the forum. I will call and ask.....

FOLLOWUP: The answer from FB was that while additional insulation is not "necessary", it is okay to add insulation, much like people do with the vermiculite in the outdoor enclosures. The assumption, of course, is that the added insulation is not "combustible". I think mineral wool qualifies as non-combustible.

Their concern was that for indoor installation, we used the proper multi-wall venting pipe, which we have. I have now fired the oven as hot as I dare (outside dome temps of 950F) and the temps outside of the factory-supplied insulation don't really get above 120F. I feel pretty good about adding insulation in the hope it will hold the heat in even more.

[Tscarborough]

Re: Additional insulation for modular ovens

It is always prudent to check both code and manufacturers recommendations for non standard installation, we agree on that.