Ovens have a chimney! WhatTF!??

[Logic]

I was asked to have a look at a stove-oven recently and was flabbergasted to discover they have chimneys!
And what seems to be air intakes below the glass window in front.

So; heat the oven at great expense,
then
exhaust all the hot air out into the kitchen.
Then
cool the kitchen at great expense!

I was flabbergasted! I was angry!
I was shoving pot scourers into that scam-ney as fast as I could!

I was happy to hear that my friend's electric bill had dropped even more than the temperature in her hot kitchen!

[redpoint5]

I've wondered if that's just so you know when something is burning.

I convection bake now, which allows the oven to run for a shorter duration.

[Piwoslaw]

I wonder whether one of the reasons for this is to cool the outer casing of the appliance?

This would extend the lifetime of the electrics & electronics between the interior and exterior, and also be a safety feature where you do not have an appliance whose surface temperature is hundreds of degrees.

I wonder if adding internal insulation would help with energy efficiency while not hindering the airflow?

[cRiPpLe_rOoStEr]

Other than wood-fired ovens and stoves, which are still fairly common for home heating in my country and sometimes pointed out to provide a more "authentic" taste for food, the only times I saw a chimney on a gas-fored oven were some pizza ovens. I don't know why.

[Piotrsko]

My 3 year old expensive as heck electric has a mini chimney, and a fan. Gotta keep them electronics cool when you're pulsing the high frequency coils. Throws a hissy when you obstruct the chimney and pouts for a couple hours.

[Piwoslaw]

Originally Posted by Piotrsko

My 3 year old expensive as heck electric has a mini chimney, and a fan. Gotta keep them electronics cool when you're pulsing the high frequency coils. Throws a hissy when you obstruct the chimney and pouts for a couple hours.

So this fan is not for circulating air inside of the oven, but specifically to increase venting through the chimney?

[Logic]

NB this chimney came from inside the oven, out the back and upward a short distance.
Intake seemed to be below the front glass.


The basics for any new to all this:

If the thermostat for air temps is set to at 200C for eg.
Then the metal interior should be at around 200C too.
And stay there.
UNLESS
you let the hottest air convect out the top and replace it with cool air from below.
A 'Click" from the thermostat and the element is on again.

Any airflow over these interior surfaces increases the amount of heat, in Watts, (NOT temperature, in C, F, K) can be transferred though the surface, to the area between skins where you are trying to keep electrical bits cool:

Air is stiller the closer it is to a/the surface. (The 1st layer basically stands still)
And STILL air is a great insulator.
Any airflow in the oven buggers that up some...

So if you want to put a chimney between skins to vent accumulated hotter air there to keeps electrics etc from getting hot; yes.
Especially if you need a bit of airflow over a heatsinked Mosfet or something.
And more especially if there's heat insulation on the interior oven walls' exterior surface.

The only advantage of a chimney I can think of (so far) is that you can smell whats happening in the oven timeously..?

But maybe radiative heat from the element/s to the interior oven surfaces, buggers up all my above er... logic completely!?

[Piotrsko]

Actually it has 2 fans, ONE "circulates" the interior, the other cools the electronics either computer, mosfet or igbt. Apparently the inner one causes a faster cooking process for things that tolerate air flow or items that prefer a dryer process. Evens out the temperature through the oven. Works a treat on baked goods and chicken.

Oddly it only has an inch of fiberglass mat between the oven and control electrics and nothing between the transducers to control board

[redpoint5]

Originally Posted by Piotrsko

Actually it has 2 fans, ONE "circulates" the interior, the other cools the electronics either computer, mosfet or igbt. Apparently the inner one causes a faster cooking process for things that tolerate air flow or items that prefer a dryer process. Evens out the temperature through the oven. Works a treat on baked goods and chicken.

Oddly it only has an inch of fiberglass mat between the oven and control electrics and nothing between the transducers to control board

Convection baking is the same as an air fryer. Reduces baking time and produces crispier results. It's how I achieve a dark bark on pulled pork after cooking it sous vide.

[Piwoslaw]

Originally Posted by Logic

The only advantage of a chimney I can think of (so far) is that you can smell whats happening in the oven timeously..?

And this might be the closest to the purpose of the chimney: To allow air, especially moisture, to escape. Otherwise it might condense somewhere inside, which is not good.

I have seen on occasion a steady flow of steam from the back of our oven when baking something with lots of moisture (pie with fruits, for example).

Additionally you can smell the baking (burning!?!) much sooner than if the oven were sealed pretty well.

[I'll add that the oven cannot be air-tight, as when it starts to cool the cooling air would contract and suck the door shut.]