new build in werribee

[oasiscdm]

Re: new build in werribee

Hi guys

I will keep measuring, but the results won't differ. On one test I rested the thermometer on each surface and got the same results, inside hotter than SS hotter than granite. Margins huge. Can't explain it but that is how it was.

[david s]

Re: new build in werribee

I struggle with the idea that different materials in contact with each other can have different temperatures over a sustained period possibly the SS "feels" hotter due to it's better conductivity. The higher conductivity of the SS means that it cannot be a heat break as it will just transfer heat across in an effort to equalise . For a heat break you need high non conduction i.e insulation

The first oven I built had a small rock with"PEACE" etched into it. It was set into the front of the outside of the oven above the outer arch. Being both black and far denser than the surrounding cement/ sand/ lime shell that contained it, it would become much hotter than the outer shell. We used to use it as a test to see if the oven was hot enough for pizza. If you couldn't hold your hand against it, then the oven was ready. Meanwhile the shell that surrounded it was hot, but you could still hold your hand against it. A second example of this is with my mobile oven which is built over a 3" Hebel base. This base sits in a steel cradle which has 40 x 4 mm galv steel bars supporting it underneath. When the oven heats up and the temp climbs the Hebel is just warm, while the steel is noticeably hotter to the touch.

I totally agree that a heat break should be made of an insulating material, but if stainless must be used for purposes of durability then it should be as thin as practicable, preferably only on the exposed surface.

[oasiscdm]

Re: new build in werribee

Hmmmm my IR gun is 50:1. Might pose a small problem.

[Toomulla]

Re: new build in werribee

Yep I can adjust the emisivity on my gun. But to what?

You set the gun to match I.e if you want to read SS set it to 0.1 and if granite 0.9

You also have to match the spot size to the width of the material i.e if the material is 12 mm wide the gun needs tone about 12 times that max away from the material assuming a 12 :1 angle for your gun

[oasiscdm]

Re: new build in werribee

Not seeing it in my results now I know the trap. oven side of hearth was hotter than the stainless which was hotter than the granite. SS is stuffed with calsil, 3mm gap to granite all working as it should. Unless I of course ang that was consistent in over 30 instances of reasons at various times as the oven moved to clearing temps.

Angle the IR gun then that all changes. DRAMATICALLY

Any how I'm a happy chappy.

[Toomulla]

Re: new build in werribee

I struggle with the idea that different materials in contact with each other can have different temperatures over a sustained period possibly the SS "feels" hotter due to it's better conductivity. The higher conductivity of the SS means that it cannot be a heat break as it will just transfer heat across in an effort to equalise . For a heat break you need high non conduction i.e insulation

[david s]

Re: new build in werribee

Yes, I shal retest at some point. But the stainless was still way hotter than the arch on which it was resting because I could still hold my hand against the arch, but no way could I have held my hand on the stainless. I think I could have fried an egg on it. So the principle still stands that the more conductive material attracts heat to itself and can be hotter than the material that surrounds it.

[oasiscdm]

Re: new build in werribee

Yep seems to confirm my son and my tests. Due to the various surfaces during emmisivity of him might prove difficult. I also have thermocouple and a 500c max thermometer. All gave me accurate readings.

Comparable to the it gun held 90deg to the surface.

Lesson learned heat break works. And I do not have to oxy out the SS

Be interested David in your re-test results.

[david s]

Re: new build in werribee

Looks like I may have to repeat my test.

http://www.fornobravo.com/forum/8/my-40-inch-pizza-oven-florida-19083-32.html#post158522

[oasiscdm]

Re: new build in werribee

Yep I can adjust the emisivity on my gun. But to what?

[Toomulla]

Re: new build in werribee

The variance most likely relates to the emissivity of the materials which can vary between 0.1 for polished surfaces to 0.9 for granite good IR thermometers can be adjusted to accommodate the variance

[brissie]

Re: new build in werribee

I can confirm the behaviour. When I check my oven the same happens, IR guns don't like some reflective surfaces or materials.

Weeks ago I did the same testing on my chimney and had the same result. I don't have any granite, but even dull (not shiny) SS reflected infra-red... interesting, that the properties of infra-red light acts different to visible light.

Years ago I did some infra-red photography, using now ancient film technology. Landscapes where surreal with this spectrum. It acts different to visible light that we are used to. It would be interesting if someone had a infra-red camera to check what it looks like from an IR perspective.

Cheers,

Steve.

[UtahBeehiver]

Re: new build in werribee

Interesting observations on the IR gun, will have to try it next time I fire up. Right now I have a 12" of snow on my oven

[oasiscdm]

Re: new build in werribee

Ok am about to give you a lesson. I thought I had made a monumental error with my heat break. SS tube stuffed with Calsil surrounded by calsil with 3mm air break to Granite landing. This morning when I took readings 12 hours after firing I had these readings

heart 120c SS 190c granite landings 230c. this made no sense to me. SO I have been thinking all day how to remove the SS.

My son came over for first pizza night. Cranked it up to 500c and discussed the readings with my son. we mucked around and found that if the IR gun is angled the temps from the SS and Granite read high. If IR gun held at 90deg to surface the readings were. Hearth 120c SS 70c Granite 60c.

it appeared the IR gun and the reflective surfaces [SS and Granite] effect the results. we checked this out at least 30 times while firing the last readings were at clearing temps were

Hearth 420c SS 220c Granite 160c gun held at 90 deg. angled Hearth 420c SS 495C Granite 360C

[oasiscdm]

Re: new build in werribee

Hi Liteceeper

Stuffing recipe

1 tablespoon olive oil
1 small brown onion, finely chopped
2 middle bacon rashers, trimmed, finely chopped
1 garlic clove, crushed
1/3 cup macadamia nuts, chopped
1/3 cup roasted pine nuts
2 tablespoons maple syrup
2 cups fresh multigrain breadcrumbs [or substitute]
1 egg, lightly beaten
2 teaspoons chopped fresh thyme leaves


Make Maple macadamia stuffing: Heat oil in a frying pan over medium-high heat. Add onion. Cook, stirring, for 3 minutes or until softened. Add bacon and garlic. Cook, stirring, for 4 to 5 minutes or until bacon has browned. Add macadamias. Cook, stirring, for 1 minute. Remove from heat. Cool for 10 minutes. Stir in maple syrup, breadcrumbs, roasted pine nuts, egg and thyme. Season with pepper.

And enjoy I rubbed the chicken with smoked paprika under the skin.