To understand what a convection oven is and how it works, we need to go back to a little bit of basic high-school physics. Before we start it’s also worth noting that these ovens are also sometimes called turbo, fan, boost or turbo-boost ovens.
Manufacturers are always looking to make their product sound new and different!
In school, you were probably taught that heat is transferred by one of three mechanisms:
- Conduction;
- Convection;
- Radiation.
To think about this in cooking terms, when you’re griddling a piece of bacon it’s in direct contact with a very hot surface (the griddle). That’s an example of cooking primarily via conduction – the heat is being directly conducted into the bacon by a hot surface.
Now before the physics gurus jump up and protest, yes, there are also other forces in play that are helping the cooking but we’re keeping this simple!
By contrast, when you’re broiling something, the heat is primarily radiant heat from the hot wires that is moving across a gap to cook your item – in other words cooking by radiation.
If you’re roasting in say a conventional gas or electrically heated oven, there will be a heat source that is heating up some form of surface. This will radiate heat onto the thing being cooked as well as heating all the air in the oven. This hot air will in turn circulate and help cook through natural convection processes.
The principle of convection cooking is simple – anything can be cooked by hot air even if it is not directly facing or touching a visibly hot surface.
Convection ovens have been around a long, long time – including the traditional pizza oven. Oddly, over recent decades the fact that this is so seems to have been forgotten and people have re-defined the term to mean more specifically, modern power-assisted ovens.
Problems With Convection
Well, there aren’t any really apart from the fact that when using a conventional oven and convection cooking, as many previous generations have done, you can get two problems arising. Again, a little bit of physics:
· it’s not always easy to get an even temperature when the hot air is left to its own devices and one can get ‘cold spots’ (relatively speaking) that may lead to uneven cooking;
· the item being cooked has a natural thermal insulation barrier of cooler air around it which means the hot ‘cooking air’ has to be that bit hotter to disperse the cool air layer.
Needless to say, technology has come up with the answer – the modern convection or ‘fan oven’.
Using A Fan
A modern convection oven uses an electrically driven fan to push air around the inside of the oven. This means not only that the temperature is even and cold spots hopefully avoided, but also the cooler insulation layer around the item being cooked is literally ‘blown away’.
That’s good news because it means that typically you can cook faster and at a lower temperature in a fan-assisted oven than in the old conventional models. Different manufacturers claim different things but a temperature difference between the two of around 40-50F is often cited. That means not only should things cook at a lower temperature but also that your energy bills are going to be reduced.
Hybrids
In the modern kitchen, ovens and other cooking devices are increasingly designed and built to support multi-function cooking.
It’s possible to purchase microwaves that also use convection and radiant heating to cook certain foods. Many ovens now have both radiant heat (for crisping the outside) plus fan assisted to drive an even cooking of the whole item.
This can be a huge help if you enjoy cooking because it’s possible to cook and obtain ‘finishes’ now in one form of even where previously 2-3 may have been necessary.
So if you’re lucky enough to have one of these multi-function ovens, make an experiment or two. You may be pleasantly surprised at the results!
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