Turning an oven into a convection oven

[Rakehellion]

I wan to turn my gas oven into a convection oven for browning roasts. Some people suggest cutting a large hole in the back of your oven to accommodate the new fan, or stick a fan in the bottom of your oven with the cord hanging out the door. These are all, of course, absurd.

Is there a place I can buy a large wind-up fan? Or is there somewhere I can have one custom made?

 

[Capt Caveman]

I wan to turn my gas oven into a convection oven for browning roasts. Some people suggest cutting a large hole in the back of your oven to accommodate the new fan, or stick a fan in the bottom of your oven with the cord hanging out the door. These are all, of course, absurd.

Is there a place I can buy a large wind-up fan? Or is there somewhere I can have one custom made?

Hmm...

 

[IronWing]

Place a live duck in the oven. As the oven heats the duck will jump around flapping its wings thereby creating convection.

 

[MagnusTheBrewer]

You're scaring me. What gave you the inspiration for this 'novel ' approach?

 

[Rakehellion]

Hmm...

:awe:

 

[Rakehellion]

Place a live duck in the oven. As the oven heats the duck will jump around flapping its wings thereby creating convection.

But then I'll need another duck to create convection for the duck I just roasted and another duck for that duck, creating an endless cycle of duck roasting. That won't work at all!

 

[NetWareHead]

A wind-up fan? I think your suggestion is not a good idea. A gas oven is carefully engineered so that air enters from the bottom of the oven and combusts with fuel which rises into the oven chamber before exhausting out the top, usually near one of the burners. The entire operation of the oven is designed around the buoyant effect of heated gases rising.

Keeping this in mind, anything which interrupts the natural draft of this airflow (like a fan) throughout the oven could be dangerous at worst or won't heat the oven at best.

This is also the reason why electric ovens were the first to go convection, They can blow a fan in any which direction and there is no draft to potentially interrupt. They have convention gas ovens now but these have been expressly designed for this purpose.

 

[IronWing]

But then I'll need another duck to create convection for the duck I just roasted and another duck for that duck, creating an endless cycle of duck roasting. That won't work at all!

To break the cycle, use a goose.

 

[destrekor]

But then I'll need another duck to create convection for the duck I just roasted and another duck for that duck, creating an endless cycle of duck roasting. That won't work at all!

I'm sure there's a market out there.

Might have to be careful about raising too much attention though - sounds like something PETA would love to hear about.

 

[destrekor]

To break the cycle, use a goose.

:awe:

 

[Rakehellion]

You're scaring me. What gave you the inspiration for this 'novel ' approach?

Probably the fact that I'm a genius.

It would be a vertically-facing fan sitting on the bottom rack using large blades and a slow rotational velocity to conserve energy.

I'm not expert on 18-century engineering, but I'd imagine this could spin for an hour before it needs a re-winding.

 

[MagnusTheBrewer]

Convection ovens are old school. A roll of duct tape to seal the seams, 25 gallons of water and, you've got your very own large capacity sous vide cooker.

 

[mmntech]

IIRC, gas overs already work a bit like a convection oven anyway. It's a moister heat than electric. So what the OP is wanting to do is pretty pointless.

 

[Rakehellion]

A wind-up fan? I think your suggestion is not a good idea. A gas oven is carefully engineered so that air enters from the bottom of the oven and combusts with fuel which rises into the oven chamber before exhausting out the top, usually near one of the burners. The entire operation of the oven is designed around the buoyant effect of heated gases rising.

Well, there's only one way to find out! The fan is intended to create a gentle breeze, not a hurricane gale.

 

[arkcom]

Keeping this in mind, anything which interrupts the natural draft of this airflow (like a fan) throughout the oven could be dangerous at worst or won't heat the oven at best.

Like, say, a large pan with food in it?

 

[NetWareHead]

Well, there's only one way to find out! The fan is intended to create a gentle breeze, not a hurricane gale.

Then my one suggestion is that you try this with a carbon monoxide detector close to the oven. I'm serious. And good luck

Like, say, a large pan with food in it?

if the pan blocks the airflow, sure that can be dangerous

 

[destrekor]

Like, say, a large pan with food in it?

That's an object in the draft's upward progress, not something inherently destroying the natural convective forces.

Unless said pan blocks the entire air gap in the oven, so that no air can rise from below, it's merely a passive rock in the stream, which will flow around it and, naturally, saturate every part of said rock over time.

The fan will be creating an artificial current on top of the natural thermodynamics. I can't say whether it will help, hurt, or what... but it should be clear that, naturally, that hot air will rise up, encounter something, and the pressure differentials will naturally try to balance out by spreading out and ultimately finding an escape.


It's much like water flowing: you may have a very gentle stream, and you're measuring sediment patterns or something down-river. At the head of the river, or at least up-river, you install an accelerator/pump/turbine system of some sort (perhaps power-generation?)... whatever you were measuring before, will likely be impacted by this artificial addition to the natural forces.


Convection ovens are designed from the ground up, so internally, the rules play much like nature enhanced itself, as the system is predictable. Altering a predictable system to try and match an entirely different system can have unintended consequences.

It might work fine, might work even better - or it could be terrible in every way.

 

[Rakehellion]

Then my one suggestion is that you try this with a carbon monoxide detector close to the oven. I'm serious. And good luck

Gas stoves don't produce carbon monoxide, you silly goose. That's wood burning stoves.

if the pan blocks the airflow, sure that can be dangerous

I'm thinking this would increase airflow.

 

[NetWareHead]

Gas stoves don't produce carbon monoxide, you silly goose. That's wood burning stoves.

Improper combustion of any fuel produces carbon monoxide. By altering the air flow, you run the risk of disturbing that very air flow a gas oven depends on for proper operational safety.

Like I said, good luck.

 

[Rakehellion]

Improper combustion of any fuel produces carbon monoxide. By altering the air flow, you run the risk of disturbing that very air flow a gas oven depends on for proper operational safety.

Like I said, good luck.

How do you improperly combust something? I'd imagine it combusts or it doesn't.

 

[destrekor]

How do you improperly combust something? I'd imagine it combusts or it doesn't.

fuel-air mixtures can and do change when other environmental variables change.

have you seriously never heard of partial combustion?
Thermodynamics and combustion are not binary systems - this is nature, which loves to fuck with us at every turn when we forget.

 

[NetWareHead]

How do you improperly combust something? I'd imagine it combusts or it doesn't.

Natural gas is primarily methane which is CH4. CH4 + 2 O2 = CO2 + 2 H2O The exhaust products are 1 part carbon dioxide and 2 parts water vapor. This is considered optimal combustion with ample oxygen.

Keep in mind that air needs to enter the bottom of the oven via a draft, there is no fan to help push it in, it relies on natural drafting caused by buoyant effect of hot air rising. if you disturb this natural flow of air with a fan, you may create a situation where not enough oxygen enters the oven and not enough to properly combust.

When you retard the supply of oxygen, instead of CO2, you get CO which is carbon monoxide (note the missing oxygen atom). A gas oven exhausts into your kitchen breathing space. This is how hundreds of people die each winter due to improperly tuned stoves/boilers/furnaces etc... Not just wood stoves.

You may not achieve a condition that I am describing, but knowing what I know about gas and combustion, I would not try this if I were you. Thats why I said to have a carbon monoxide detector around if you do this.

 

[DrPizza]

I agree completely with netwarehead. This is a risky experiment. Look at the burners on a natural gas stove. If the flames are blue, no CO. Red, yellow, or orange flames indicate incomplete combustion. Possibly recirculating the water vapor and CO2 into the flame will result in the production of CO.

My suggestion: Build a second "bottom of the oven" - that is, create a 1" space between the existing bottom, and another completely layer of metal, with only a slight increase in the total area of holes in it (for combustion gasses from the oven) to rise through. Then, the fan idea might work; in fact, would probably be fairly simple to do. ABSOLUTELY have working carbon monoxide detectors if you do this. Also, if there's any way you can monitor the flame color, that would help indicate to you if you have an obvious problem.

 

[gorcorps]

Probably the fact that I'm a genius.

It would be a vertically-facing fan sitting on the bottom rack using large blades and a slow rotational velocity to conserve energy.

I'm not expert on 18-century engineering, but I'd imagine this could spin for an hour before it needs a re-winding.

What were you going to make your spring out of? Because any spring steel will have so much thermal expansion that you won't have a spring anymore at oven temps. It'll only rotate when the oven is off

 

[LTC8K6]

Crack the door open a bit. That should create air flow, and warm up the kitchen.