cheap excellent material for oven walls

[ublinkd]

All this new info is....wow...just crazy! I can't believe this stuff absorbs that much water. Not saying I don't believe you, not saying that at all. I was under the impression that this stuff was much more "sealed up". This new info puts a big damper in my plans cause I was about to buy this stuff to build my oven. Dang looks like it is time to do more research.

Art

[Scratch]

Me too... I think I'll just be safe and go with tried and true sheet metal.

[Waorani]

Just in case - a bit of clarification - while my oven in its original condition would heat to 200F, I was trying to abandon that given that I wasn't sure if elements/fans/etc could handle the 400+ PC temps. The 5200W I have installed is the only heat source for a 4x2x5=40sq ft oven. I'm also beginning to worry that even if it does dry out - will it again absorb moisture when not in use?

[67shelby]

I too saw a lot of moisture at first. But it has slowed down. I'll bear that in mind as I post my results. I should get my sheet metal for the top and doors tomorrow and I'll do the top and run my tests and then the doors and run my tests and let you all know.

[67shelby]

Preliminary results:

For all tests, insulation is in place entirely around the oven, all tests are from a cold start in a pretty constant heated room (my shop has hydroponic heat in the floor).

6x3x3 oven with 3/4 inches of backer board on the top (1/4 inch piece overlayed by 1/2 inch piece).

20 minutes - 275 degrees.

with just 1/4 inch backer board (1/2 inch backer board removed) in the top.

20 minutes - 285 degrees.

with the 1/4 inch backer board covered by 24 gauge sheet metal offset by a metal 2x4.

20 minutes - 325 degrees.

So, I picked up 40 degrees by covering the top backer board. After opening the doors and jumping up and down in excitement, I let it go another 10 minutes and it read 375 degrees. The highest I had hit previously was almost 400 but after about an hour.

Later this week, I get rid of the backer board on the doors (1/2 inch) and try again, hopefully, I'll pickup another 25 or 30 degrees in 20 minutes. I have just a little more backer board to cover on the sides and that could be next...

I guess you can make your own decisions, but this pretty much made up mine.

[TurboRoadster]

I have a backer board interior, havent fired it up yet, but also, I have ordered 1/2 gallon of high temp silver paint to seal the board and cracks. hope this will help reduce the boards heat absorption and aid in reflection. I'll post up when it gets fired up, 6x3x3 interior

[Banditperformance]

Originally Posted by Waorani

This stuff apparently holds a lot of moisture. At our local Lowes its stored outside and gets rained on frequently. Hopefully it will eventually dry out. Anyway, if you're looking at using it for an interior lining though - you might want to store in dry place for a while before mounting and firing up.

First I have heard of that?? HardiBacker was developed for Bathrooms and WET enviroments. At my hardware store, they have a 6" piece in a plastic case that is filled with water. Been there as long as I remember, and it's still solid. You can rattle it around in the container,

[67shelby]

Originally Posted by 67shelby

Preliminary results:

For all tests, insulation is in place entirely around the oven, all tests are from a cold start in a pretty constant heated room (my shop has hydroponic heat in the floor).

6x3x3 oven with 3/4 inches of backer board on the top (1/4 inch piece overlayed by 1/2 inch piece).

20 minutes - 275 degrees.

with just 1/4 inch backer board (1/2 inch backer board removed) in the top.

20 minutes - 285 degrees.

with the 1/4 inch backer board covered by 24 gauge sheet metal offset by a metal 2x4.

20 minutes - 325 degrees.

So, I picked up 40 degrees by covering the top backer board. After opening the doors and jumping up and down in excitement, I let it go another 10 minutes and it read 375 degrees. The highest I had hit previously was almost 400 but after about an hour.

Later this week, I get rid of the backer board on the doors (1/2 inch) and try again, hopefully, I'll pickup another 25 or 30 degrees in 20 minutes. I have just a little more backer board to cover on the sides and that could be next...

I guess you can make your own decisions, but this pretty much made up mine.

The last test was today, I replaced the backer board on the doors (2 - 1/4 inch pieces). In 20 minutes, the oven reached 375 degrees. I hit 425 degrees at 30 minutes after having opened the door at 20.

[TurboRoadster]

^^ awesome, I just finished the interior painting on mine and am working on the final stages of the door contruction.

[Waorani]

Originally Posted by TurboRoadster

^^ awesome, I just finished the interior painting on mine and am working on the final stages of the door contruction.

Interested in hearing your results before I rip the hardiboard liner out of my oven. I had already bought some aluminum high temp paint but hadn't put it on yet given initial dissapointing results. Did you attempt to dry it out any before painting?