Dome insulation - is this enough?

[applor]

Hey guys,

So I haven't made a thread about my WFO build in Brisbane but plan to post with all the pictures when it's done.

I am currently organising my ceramic fibre blanket and will be buying from Total Refractory Management | Welcome To Our Homepage

This company also sell WFO kits so they have experience in this field.

When ordering I said I needed enough blanket for 75mm (3") of cover on my 40" dome, to which I was told that is way overkill.
Apparently 50mm would be more than enough, in fact they only sell enough blanket for a 25mm cover for their WFO kits!

Now I definitely want more than 25mm but do you think 50mm would be enough blanket? I should accept that they know their product and wouldn't lie (hell they make more money by selling me more blanket) but also once the dome is done there is no going back.

lastly, do you guys insulate your entry and around the smoke stack? I read that it is not in any way required, since after heat leaves the dome it is useless anyways.

[cobblerdave]

Re: Dome insulation - is this enough?

Gudday
I built my oven a number of yrs ago and a box of 25 mm ceramic blanket from TRM covered 50 mm over the dome bar lower 100 mm. My dome is outside the floor so basically the dome is covered. I find it works well but 2 boxes would be more than enough for 75 mm with heaps to play with. You can't over insulate.
Regards dave

[applor]

Re: Dome insulation - is this enough?

Thanks for your response. So you are saying you wished you'd added more than 50mm of insulation?
How big is your WFO? Mine is roughly a 40" and TRM say that a box of 25mm blanket (7200mm x 600mm) is enough for 2 layers.

[cobblerdave]

Re: Dome insulation - is this enough?

G"day
Mines a 42 in oven and has another 4 ins of fiberglass insulation over the 2 in of ceramic insulation. It was only possible to use the fiberglass insulation because of the efficiency of the ceramic.
http://www.fornobravo.com/forum/3/hi...tml#post114790

Regards Dave

[oasiscdm]

Re: Dome insulation - is this enough?

I used 50mm of shiralite and 50mm of ceramic blanket. Next build I will use 75mm of blanket and still stick with the shiralite. I also used high build render which apparently has some insulating properties although not convinced about this but what I have been told.

[boerwarrior]

Re: Dome insulation - is this enough?

applor

I have a 32 inch oven and I went for the overkill approach. I have 2 layers of 1.5 inch ceramic blanket followed by several bags of loose vermiculite (My dome is enclosed).

It didn't cost much relative to the cost of the total oven and I have never laid awake thinking "I have too much insulation." When it is 1,000 degrees inside my oven I can not register a rise above ambient temperature at the top of my dome roof. This does not make me unhappy. 3 days after I fire my oven (and leave the door on) the interior temperature is still around 350 degrees. Again, never been sad about that.

I think insulation is like money, sex and TV-size: It's hard to get too much!

[applor]

Re: Dome insulation - is this enough?

Sounds like I should play it safe and buy a second box then. At $115 it's not cheap but small compared to the total project so I don't have an issue.

4 layers of 25mm or 2 layers of 50mm?

[applor]

Re: Dome insulation - is this enough?

just got back from TMR, went with a box of 25 and a box of 50 so will have more than enough.
Will be short on the calsil board though but I have enough for the dome just not the landing which I read doesn't really need to be insulated.

[Greenman]

Re: Dome insulation - is this enough?

You will not be disappointed with your decision. There is no going back after if you cut it short with the insulation. I put 50mm of CF over the dome and the vermicrete over that. The oven is 36" and I am happy with it. It depends on how you want to use your oven. I use mine to cook pizza then next day to bake and the day after to slow cook casserole and the like.

You can always add some fire for a short burst if temps drift below what is needed.

All the best with your build.

[cobblerdave]

Re: Dome insulation - is this enough?

Gudday
Round dome , square sheets, cut the corners off the dome, use the triangles to fill in the entrance.
Regards dave

[GianniFocaccia]

Re: Dome insulation - is this enough?

Here's how mine ended up. I installed three (12'x24"x1") rolls which covered 4" all around with 2" extra on top on a 39" dome.

[applor]

Re: Dome insulation - is this enough?

Gudday
Round dome , square sheets, cut the corners off the dome, use the triangles to fill in the entrance.
Regards dave

Yeah this is what I plan to do, however there will only be enough for half of the front landing.
I will have to use something else to support the front half.

I am pretty excited now though, given I have most of the materials and no stopping me from completing it.
The support bricks arrive today so bricklaying is the next step. They are sandstone imitation besser blocks so no render required.
I am also picking up the pre-cut reo bar for the floating slab tomorrow.

[applor]

Re: Dome insulation - is this enough?

Here's how mine ended up. I installed three (12'x24"x1") rolls which covered 4" all around with 2" extra on top on a 39" dome.

Looks good!
How'd you find cutting the blanket?

I got a whole lot of warnings about the fibres and mess created with cutting the calsil and the fibre blanket so not looking forward to that part:S

[cobblerdave]

Re: Dome insulation - is this enough?

Looks good!
How'd you find cutting the blanket?

I got a whole lot of warnings about the fibres and mess created with cutting the calsil and the fibre blanket so not looking forward to that part:S

Gudday
Yep cutting the blanket you can see the fibre being released. I would recommend use a proper respirator not one of those paper masks. You can get a full disposable protection suit. As it was a one off job and I knew how hot those things can get My Personal Preference was to not to use one.
I decontaminated in the downstairs laundry shower.
The respirator is a good to have through the job too, a lung full of brick dust is not the healthiest thing ether
Regards dave

[oasiscdm]

Re: Dome insulation - is this enough?

I resemble those remarks.

I also put an extra layer on the top half. John's 4 " layer With extra on top is how I would go next time. On mine I acquired 100mm strips. so easy to install came out really neat.

I also used 50mm shiralite and would do that again even simply to lock the dome in place. Before the blanket goes on. I am also getting really even saturation. But have nothing to compare it to. Inside outside top to bottom of the brick is all the same temperature to about 2 deg. Virtually no variation. So would do this next time as well.