Poll: How hot is the outside of your igloo?

[kebwi]

For those who have built igloos (I assume enclosures are completely different in this regard but if not, contribute...but explain your enclosure briefly) how hot does the outside of your oven get? Can you estimate it numerically (or have you pointed your thermometer at it)? If not, just characterize it using "warm/hot to the touch" descriptions.

Additionally, to make this information useful, please include a description of your insulation. Blanket? How thick? Loose vermiculite/perlite? How thick? Vermicrete/perlcrete? How thick?

I know I have seen individual reports of this kind of thing throughout FB mixed into threads on other topics and I don't mean to be redundant...but this thread could represent a repository on this specific issue, easily discovered by thread topic in the future...if it accumulates enough data points.

Cheers!

[scottz]

Re: Poll: How hot is the outside of your igloo?

Hi,
I have an igloo style WFO. Mine is built of Pre-cast Refactory Cement. I find that my oven is fairly cool for up to 2 hours after getting to 'pizza hot'. At this stage I get a bit of heat coming through the top central part of the oven while the sides and around the bottom remain coolish. In terms of how hot...I would say I can easily put my hand on the top and not burn it, but there is a bit of heat there...dont think it is anywhere around the 100C mark. The insulation that I used was a fiber ceramic Fire blanket that i guess was a good 2 to 3 inches thick. It was then covered to 2 coats of render. I was a little concerned with the heat loss to start with, but since then I have done a fair bit of slow cooking and the oven retains heat enough to do roasts and other things for 8 hours and more, so I guess its ok for the type and length of cooking we do. I know I can have a good cook in the evening and first thing in the morning I can put my hand in the oven and it is still warmish. I hope this helps.

Scott

[texassourdough]

Re: Poll: How hot is the outside of your igloo?

My oven is also pre-cast refractory cement finished to FB standards and my oven is never more than warm to the touch - even after three or four hours EXCEPT near the chimney connection where it gets pretty warm over time. And yes, my chimney can get HOT!
Jay

[kebwi]

Re: Poll: How hot is the outside of your igloo?

@Jay: Would you mind giving more detail about your instulation? There are multiple prescriptions in the Pompeii directions. You can use a blanket or not, instructions for both are given? Did you use a blanket? How thick? What sort of vermiculite layer did you add?

[texassourdough]

Re: Poll: How hot is the outside of your igloo?

Hi Kebwi!

As indicated, my oven starts with a precast dome from FB. I added about an inch of additional refractory cement to give it a bit more mass. Then the refractory insulation blanket which I recall being about an inch thick, maybe an inch and a half. Then foil. Then chicken wire and about two inches of cement and vermiculite. Then stucco. At least that is how I remember it from five years ago.

[heliman]

Re: Poll: How hot is the outside of your igloo?

Mine is barely warm (the cats sit on it as proof of its mild termperature).

I would guess that it its tempertature is no different to a brick that has been left in the sun for a while.

Rossco

[kebwi]

Re: Poll: How hot is the outside of your igloo?

@heliman: That's great. Let us know how you insulated it.

[martywatts]

Re: Poll: How hot is the outside of your igloo?

I have not put a finished veneer on yet, but after the several full firings we have done, the outside of the dome is barely above room temperature. That varies only slightly as you get closer to the entry of the dome where the insulation is not as thick as the rest of the dome. I insulated with 1 to 2 inches of mineral wool then covered everything with 5 inches, more in places of perlite concrete mixed 12 to 1. The dome is as per forno bravo plans using fire brick.

[Wiley]

Re: Poll: How hot is the outside of your igloo?

Even after firing for some an extended time there is very little to no detectable difference between the exterior temp of my dome and the exterior temperature of the support base. This is not true near the very top where the chimney exits.

The exterior dome of my WFO is a shell and not supported by the interior mass of the oven but rather is a separate free standing structure. Over the thermal mass of the WFO I have 3 inches of kaowool insulation on the lower side areas and as one moves up the dome toward the top that thickness increases to 4 inches with five or so at the very top. Between the outer surface of that kaowool insulation and the inner surface of my dome shell there is infill of loose vermiculite. This infill varies from about one inch to perhaps as much as three inches.

Hope this helps,
Wiley

[3G_]

Re: Poll: How hot is the outside of your igloo?

I used 3 layers of insulation (25mm thick) My dome gets alot hotter in the sun during the day than during a nights cooking. I would say no hotter than 40degrees C. I was amazed at how good 3 layers of insulation is.

[DimTex]

Re: Poll: How hot is the outside of your igloo?

I bought 3 boxes of the insulfrax insulation for my 36 inch oven. It gave me enough material to clad my dome in four layers and still have a little left over (anyone want it?). Then about an inch or so of 3 layer stucco. The exterior of my igloo have never gotten hot, it has always remained just about the temperature of the ambient air, even after a few hours of 850 degree plus heat inside the dome. As someone mentioned in an earlier post the connection between the dome and the double wall chimney does get warmer as does the chimney itself, but you would have to reach up to burn yourself (if you're into that kind of thing).

[kebwi]

Re: Poll: How hot is the outside of your igloo?

This is all great news. Everyone keep piping in. This thread will be of invaluable assistance to future builders...including myself given that this stage of my project is in my future (on the order of days though!).

Cheers!

[heliman]

Re: Poll: How hot is the outside of your igloo?

Sorry but I cheated and had a WFO company build mine for me.

I recall that they used some very thick insulation and I will see if I can find out the details as they are coming back to fix a problem.

Rossco

@heliman: That's great. Let us know how you insulated it.

[scottz]

Re: Poll: How hot is the outside of your igloo?

Sorry but I cheated and had a WFO company build mine for me.

Rossco

Was the company the mob in Freo by any chance?? And if so have you been to any of their Demo days??

[heliman]

Re: Poll: How hot is the outside of your igloo?

There are a couple in Freo these days - yes, it was one of those. Have had the oven about 7 years now and went to a few of the sessions in the early days.

Had one of the guys come around to show me how to bake bread too - from memory we made about 14 loaves which was a problem with only 2 of us in the house!!!

BTW I work in Osborne Park and there is a place nearby called Kitchen Warehouse and they have a woodfired oven inside the shop. They have lots of pizza related gadgets too and often do classes on cooking/pizza making which I believe is quite well supported. I got my tomato sauce attachment from there yesterday. Worth popping in if you are in the area.

Rossco