We will sometimes get comments from people about ovens running too hot or too cool all too often with people thinking that there’s some sort of issue with the oven causing this.
If this is how you stumbled across this article then before you go to all the hassle and possible expense of replacing thermostats, heating element or fans then please consider some of the points here as, they could save you a lot of hassle and money.
Our experience is that people that have issues with time and temperature tend to be cooking either from packet instructions or from a recipe that calls for specific time and temperatures. Often the assumption being that perfect results should be accomplished by following the instructions to the letter.
But, cooking is a subjective thing to a degree and just like the ingredients, method and so forth, the appliances also have variances and quirks. Each cook has to work those out and adjust to compensate where required.
We have explained how traditional oven thermostats and newer electronic sensor types work in a few articles over the years but probably failed to mention that in general terms, these either work or do not work. They are an “all or nothing” type component as they offer a simple on or off electrically, no more.
With most you’ll either get full on heat and everything in your oven will be burnt to a crisp or, it won’t heat up at all.
When electronic sensors go faulty more often than not you’l get an error code and not a lot else will happen.
Some traditional analogue thermostats can be calibrated or adjusted but, they come preset and should never need to be. In fact, messing about with the adjustment on them can prove disastrous and field technicians will hardly ever do this. Out advice is, don’t touch it.
For most people on most issues we see around this topic, that rules out the thermostat as the cause of any problems.
How Accurate Is An Oven Thermostat
In domestic cookers and built in ovens the short answer is, not very. They really don't need to be ultra-accurate.
Most will operate with a 10-15% deviation from the set temperature. So, if you set your oven to say 200˚C it will most probably “cycle” the heating element on at about 180˚C and off around 220˚C giving a mean or average temperature of about the set 200˚C.
However it has to be stressed that mileage may vary here as these numbers can vary, in some cases quite dramatically as on cheaper cookers the thermostats tend to be lower quality and, less accurate.
For a domestic oven thermostats don’t really need to be more accurate than this for most everyday cooking purposes. Okay, some of the really poor quality ones are really bad, especially gas oven ones but that’s a symptom of the cost implications more than anything else.
You can get more accurate but for most people it’s probably not worth the far higher cost.
Heating Elements Rating
If the elements in your oven are really good and the oven heats up really quickly or, cycles more accurately or even faster then you can find stuff cooks faster in your particular oven than set out on the instructions that you are following.
Equally, the reverse is true. If the elements are not that great and the thermostat not that accurate it may cook “cool” and your cooking will take a little longer.
An old rule of thumb when fan ovens first started to get popular was to experiment with them to a degree by not allowing for preheating and to reduce the temperature by 10%. The latter still holds true as a fan oven will heat more evenly and cook faster than a traditional static oven although many recipes do benefit from preheating.
However, that’s something that the user has to work out based on experience with that particular oven.
Door & Sealing
The door seal and how well the door shuts and seals is critical.
If the hinges on your oven are a bit dodgy or the seal a bit iffy then the oven will loose heat and that will affect the cooking. So, over time, you can expect the performance of your oven to alter just based on this alone.
These are two things that, if you spot a problem, you should put right as if you don’t all you’re doing is bleeding heat into the kitchen and wasting energy as well as not doing your cooking any favours.
Oven Shelves & How You Use Them
For people that cook they know full well that, if you use a static or convection oven (not fan assisted) and you put stuff at the top of the oven it will cook faster or burn on the top.
The reason is simple really, heat rises so the oven will be warmer at the top than it is at the bottom.
But, if your oven has a lower or base heating element and you put something on a very low shelf setting then you can end up with a burnt base and barely cooked top.
The “sweet spot” is in the centre of the oven where the temperature is most even. This isn’t a failing of the oven at all, it’s just physics in action. All the cook has to do is adjust where he or she places stuff in the oven depending on the desired results.
Fan assisted ovens do away with this by giving a far more even heat through the oven cavity but you will still get some variation depending on the oven and the design.
Additionally though, if you use a number of solid shelves or baking trays in the oven then this will hamper airflow and will lead to warmer and cooler points in the oven. Same result if you wrap the wires shelves in tin foil as some people do. This can also affect static oven cooking as well.
The cooking process is reliant in many ways on airflow, whether it is fan assisted or not and anything you do to alter or even prohibit that airflow will have an effect. Sometimes that can be desired and a good thing but only if you know what you’re doing usually in terms of cooking or, you’re experimenting with your cooking.
For baking this is a good thing to know as it will affect the results.
If you’re cooking a casserole or something that’s sealed then it’s usually not just as critical although can still have consequences.
The time we hear about it is often when people have a burnt pizza base with an almost uncooked top. It’s almost guaranteed that the airflow is restricted or the pizza cooked on the lowest position in a static oven.
The pertinent point being, where you place food in your oven, the mode you choose to cook with and the shelf or accessories in the oven can and often will have an effect on your results.
Ovens Are All Different
You may by now have gotten the point that we’re making here, all ovens are different each has it’s own unique characteristics that will shape how you cook in it. And, over time how it performs can and probably will alter.
You can mix and match almost all of the above on many ovens and what you end up with is almost infinite variations on performance.
Cooking at 180˚C in one oven will almost certainly be different to cooking in another are the same temperature. Sure, it will be very similar and neither is wrong, it’s just slightly different.
Once you build up a bit of experience with the oven of cooker though these variations are rarely an issue.