Oven Temperature Testing
It is fairly common to receive complaints or concerns about the temperature of a built in oven or cooker in respect to the heat in external panels as often people think that they are too hot. The reality is that it is incredibly rare to get an oven, especially a new one, that is running too hot and causing any issue. Do bear in mind that the notes on testing are written from an industry perspective and generally intended as general instructions for appliance engineers that have the proper test equipment, not the general public.
What is all too common is that ovens and cookers are not installed correctly and, increasingly, that kitchen cabinets are not of a sufficient quality to withstand the heat produced by a built in oven especially.
Let's begin with getting some common sense stuff out the way first.
Ovens Get Hot
They are supposed to get hot, they are intended to cook at temperatures way in excess of the ambient and in order to keep the surroundings cool as well requires considerable engineering effort which in turn means that very often cheap ovens that do not have cooling fans, multiple pieces of glazing in the door and so on will get hotter than those that do.
In other words, cheap built in ovens where these features are not present will get hotter than the more expensive models that do. That's it, end of story.
So, if you bought a cheap oven and it's too warm on the outside then the chances are there is nothing wrong with it and, in over twenty years and scores of temperature tests we've yet to come across a single one that exceeded the BSI Standards. For more on the BSI Standards please see this article and a lot of the temperatures that we talk about here are based on these standards as laid out by the British Standards Institute.
Keep Children Away
Young children should not be allowed to be near an oven or cooker that is on, period.
This is simple common sense in respect to safety as, even if it is an oven which runs cool externally it will normally have a vent that will have very hot air blowing out of it driven by a cooling fan. If kids get too close to that they could burn themselves as their skin is more susceptible to burns than most adults as a general rule.
You wouldn't allow your kids to go play in the middle of a road with traffic on it or let them play about in a commercial kitchen and, you shouldn't let them be around appliances either or a kitchen in full flow. Even an oven door springing up can take a chunk out of an adult's hand let alone a child's.
In the industry we often hear comments from users like "but my child could burn their hand on it" and we're all thinking, "what's a kid doing even near the thing when it's on?". It is not the manufacturer or retailer's job to ensure your children stay away from dangerous things.
Parents shoulder the responsibility for their children and have to apply common sense to the situation, in short, keep kids away from appliances, they are not designed to be operated or interfered with by children.
Equipment Required To Temperature Test
Before you embark on temperature testing an oven or indeed a cooker of any type you need to have the correct equipment to do so. n
About the only piece of special equipment that you need is a thermometer to determine the temperature but it is special in that you need to be able to take surface temperatures, accurately. Digging out some old cobbled together bits and bobs in some sort of Heath Robinson affair will not cut it to carry out these tests at all. You need to use a proper thermometer and we would strongly recommend that you use a digital one in one of two flavours, either with a probe or, still better these days, an infra-red digital thermometer.
Using a more modern infra-red thermometer is far, far better as it allows you to take accurate readings from each test area over the course of the testing without any hassle. It's just a lot easier and these days a meter is available at sensible prices that is perfectly suitable to test an oven, you don't need some highly specified one costing many hundreds of pounds.
Without the correct equipment you cannot test the oven temperatures.
Testing External Oven Temperatures
First off, before you even switch the oven on, make sure that it is installed correctly in accordance with the installation instructions from the manufacturer. It is utterly staggering the amount of built in ovens that are seen that have not been installed correctly and in the vast majority of service calls where there is a need ask for a temperature test you will all too often find that the oven hasn't been installed properly negating the need to actually test it!
Check the Installation
Save yourself a lot of time and trouble by checking the installation first.
Also, check that there is adequate ventilation in the cabinet such as vent holes have been cut as they are very often required to ensure a flow of cool air to the oven. Failure to do this can lead to overheating issues, problems with ovens cutting out due to overheating and so on.
A simple visual inspection can often save you a heap of trouble, let's look at the primary problem areas in the diagram below so far as installation is concerned.
One of the most common issues is poor or inadequate spacing between the outer frame or edges of the oven and the adjacent kitchen units. This is indicated on the drawing by the red (sides), orange (bottom) and green (top) arrows pointing away from the oven.
For the sides in red the minimum distance should be 10mm on each side unless the manufacturer installation instructions for that particular model of oven specifically states it should be something else. The reason is that you must have a gap for air to flow and to cool before it hits any kitchen units but we will explain this more below.
The top green spacing should be likewise unless, again, it is specifically stated otherwise for that model of oven or there is a requirement (as shown) for a top vent which must be clear to allow airflow. If you do need the top vent and you block it, there will be overheating for sure. A vent at the top is usually required for conventional ovens that are not fan assisted or have a cooling fan in them as, with that type of oven, natural airflow is relied upon and the oven must draw cooler air and therefore proper ventilation is absolutely essential to correct operation of the oven.
The bottom arrows in orange tend to matter more when the oven is installed in a column stack or there's some sort of door or trim below the oven and, again, 10mm minimum gap between the surface of the oven and the next surface unless it is specifically stated otherwise.
If any of that is wrong, then that's most likely the problem and most likely the reason you are reading this article.
Testing The Temperature
First off the best thing to do is call the customer a bit before you visit and ask them to put the oven on and set it to the temperature you need for testing.
For a built in electric oven this is 200˚C and although not specified we advise that the oven is running for at least 30 minutes before you commence testing, an hour is better but for most built in electric ovens you can start as soon as the oven reaches 200˚C.
For the purposes of this example we will assume a room temperature of 20˚C as the allowed temperature rise is based on the ambient temperature of the room so you will need to do a little arithmetic here to work it out later. But make sure you note the room temperature, accurately, before you test and bear in mind that the room temperature will often rise when people are cooking, especially for extended periods and more so when a hob etc is also in use in the kitchen at the same time. It is good practice to advice the owner that even although you can give a maximum temperature that any element can be allowed to go to that it is not uncommon that in real world use that a kitchen reaches 30˚C or higher which will allow the elements tested to go a few degrees higher than your test may indicate.
So, in order here is a note of the maximum allowed temperatures in each area of the above for the oven itself.
Area A - Top Control Panel
The control panel will vary depending on what it is made from as many elements will in this example:
Metal or painted metal the maximum temperature would be 65˚C
This is calculated by adding the maximum permissible rise of 45˚C to the ambient room temperature. Obviously if the ambient rises to say, 30˚C, then the maximum changes to reflect that and becomes 75˚C.
Area B - Control Knobs
These can be up to and including 80˚C if they are plastic as most are.
It is assumed that metal control knobs should be cooler by around 10˚C but normally an oven with metal control knobs would be a bit better and have a cooling fan fitted so it's rare to get issues with those.
Keep in mind though that if the room temperature changes so doe the allowed maximum temperature and that these components can be and, are allowed under current standards, to be hot enough to burn to the touch if you hold your hand or fingers there for any time.
Area C And E - The Oven Door
This is the one you will hear the most gripes about, especially if there is no cooling fan fitted or the ventilation is hinkey.
The glass door can be a whopping 60˚C above ambient, in our example that means that the surface temperature of the oven door can easily reach 80˚C, again hot enough to burn to the touch and it's still perfectly legal and acceptable under British Standards.
If the door is metal or, as the above shoes, has a metal surround to a central glass then the surrounding metal has to be cooler.
For metal or painted metal the maximum would be 65˚C or if the surround was made from vitreous enamelled then that would increase by 5˚C to be a maximum of 70˚C. Again, quite possibly a high enough temperature to burn if your hand where held against it for any time.
Area D - The Oven Door Handle
The oven door handle can get to 55˚C if metal or 70˚C if it is plastic.
The Reasons For Temperature Testing
Ordinarily there is a reason to do a temperature test on an oven and the two most common reasons are as follows with explanations on why there is the complaint as well as how to address the issues raised by them. It is fair to say however that in 99.9999% of any of the cases where you are asked to test for these reasons, the oven will not prove to have any fault at all. In fact, we reckon you've better odds of winning the lottery three weeks in a row than finding an oven that doesn't comply to BS standards.
The Oven Is Too Hot To Touch
Usually this will be a complaint that the door, the knobs or the control panel of the oven is too hot to touch. And, as we've demonstrated above the answer to that is simply, yes it can be too hot to touch with an open hand for many people but that doesn't in any way make the oven illegal or sub-standard, it just means that the oven runs hot, that's all.
More often than not you will also find this complaint on cheap ovens banged in as a cheap or free option with a new kitchen that are stripped out or reduced specification models with no cooling fan fitted and quite possibly poor ventilation as well.
As much as you may want to, you can't say to the customer that they have been supplied a pile of rubbish and there's not a lot you can do.
The reality is however, there really isn't anything that you can do if the oven performs within the specified tolerances and no fault is found which, by the by, most manufacturers won't pay for you to find out so you are supposed to give the customer the bill for your time as well. Of course if it's a problem with the installation then the customer can take that to the installer or retailer to get paid.
The Oven Is Burning The Kitchen Units
This complaint we have to split into two things really. There is discolouration of the units to the side of the oven or, whatever is next to it as many people (wrongly) put other appliances next to ovens and coatings peeling off the adjacent units.
On both counts, first thing to do is check the air gaps as detailed above are either 10mm or greater or that the oven is installed in accordance with the instructions. If not, there's the problem.
Where the two top red arrows on the side of the door are on the diagram above however is where the discolouration issue is liable to occur as that's where almost all ovens will vent from the top of the oven cavity. What happens is that, even on an oven with a cooling fan, is that the air is either naturally driven or driven by fan there to assist in cooling the oven door and letting out the heat.
The problem here is that in every single instance that in that expelled hot air from the oven will be microscopic particles of fat and grease for the cooking process. This will stain light coloured units especially and still more so if there isn't the clearance needed to let it harmlessly out into the atmosphere, it just hits the units and stains them. Unless the installation is sorted out it will continue to to this and it is not a fault with the oven at all.
The thing is, this is misinterpreted by customers as the oven burning the units when in fact it isn't at all.
For customers that do a lot of roasting, baking and especially open roasting which is a killer for this problem, then the effect will be greater. So, ask what kind of cooking the customer is doing as it's not all about the appliance itself much as it isn't for other appliances as the way that they are used are of equal and, often greater, importance.
We said we'd split this as in recent times this is becoming more and more of a problem.
What will happen is that you will get a complain that the kitchen units next to an oven are peeling, cracking or burning. The images show you typical examples of what you will see on inspection but, these days, it may be better to ask the customer to take a few pictures of it and email them to you as you can usually advise on this without the need to call and inspect.
Our thanks to Careys of Ipswich for the images of typical door and drawer damage.
First thing, check the installation. Make sure that there is a sufficient air gap again between the actual oven and the adjacent drawer or kitchen cupboard unit. If there isn't then that will be the problem, not the oven.
Now, keep in mind here that the kitchen supplier is hardly going to tell the customer that the reason that they have the problem is due to a cheap set of kitchen units or that they didn't install the oven properly allowing enough of a gap. So they will invariably attempt to blame the oven and get the oven manufacturer to pick up the tab for any replacement units, doors or drawer fronts.
But just look at the example above. If the oven was overheating to the extent that it caused this level of damage anything you tried to cook in it would probably look as if it had come out an incinerator, not a domestic oven.
In the example above however, look closely.
Notice that the coating on the drawer isn't burnt, it's just all warped out of shape and has come away from the wood underneath it.
That's because the material that has been used, whatever it is, simply cannot stand up to the heat from the oven installed adjacent to it and it's a fair bet that this didn't take a particularly high temperature to get the coating into that sort of mess. What's very much more likely is that the material used is low cost and not specified to be able to take that sort fo heat.
Funnily enough, this is becoming more of an issue on cheap kitchens. I'm sure you're not especially surprised.
To date we have not come across a single instance where this has been caused by a problem with the oven or even a cooker, it has always proved to be an issue with the kitchen materials that have been used or the installation.
This is why we advise that you take the other temperature when testing not detailed above, F on the diagram, so as you have a record of it just in case but if the burning or marking is the issue then it should always be noted, even if it is not specifically requested.