Hi there, I have had a Neff Circotherm oven since I had my new kitchen at the back end of last year; I absolutely hate it! It doesnt go above 200 degrees, this is apparently because the fan action means that it doesnt need to. Apart from the fact that this quite clearly isnt the case ( starting off roasts by blasting them etc) I simply dont seem to be able to get temperatures right with it - I tried Jamie Oliver's slow roasted shoulder of lamb the other day and turned it down but cooked it for the same length of time and it wasnt cooked enough and yet it cremated a piece of beef rib that i cooked last week when I used the same suggested temperatures...The instruction booklet is worse than useless and I am at a loss! Does anyone else have one of these cookers? I am really looking for some help on converting conventional cooking temps to ones that work on the neff....thanks in anticipation

Hi

If you look back far enough on this part of the board you will find a post saying exactly the same things as you are.

These ovens reach the temperature setting more quickly because they blow hot air and create an air-stream which saves on pre-heat time and, to some extent, the temperature drop that takes place when you put something in the oven.

Have you got an oven thermometer? They are quite cheap to buy - Robert Dyas sell them for under a fiver. It might help you to work out what is happening to the temperature levels - also, it might be faulty anyway.

AEG make good ovens - if it's faulty or not operating as per their instruction manual, you might want to consider getting your money back and starting again?

The standard practical test is a basic sponge cake - if that won't bake satisfactorily having followed the hand-book, then I would suggest calling out the engineer, then if they confirm it's faulty, you might want to consider your options - I know what I would do.

Hi Sarah, One of my ovens is Neff Circotherm and it sounds as though you may have a problem with understanding your conversion tables.

200c Circotherm is equivalent to 250c conventional.
190 = 230
180 = 220
170 = 200
160 = 185
150 = 160
140 = 150
130 = 140
120 = 130
110 and below is the same temp in both modes.

I suggest you buy an oven thermometer, they are not expensive and check you temp ranges. Beyond that I would talk to the manufacturer.

As to use, I have had mine for several years and it works very well.

Hope that helps and good luck in the future.

David

Thank you very much for your replies. I bought a thermometer and it is sat on the oven floor currently - it reads the same temp as i have the oven set on; e.g. 180 circotherm, it says 180 on the thermometer.

I will have a go with the conversion table that Chef de Maison kindly supplied (there is no such thing in my instruction booklet).
Thanks again

Hi Sarah, try putting the thermometer on the middle shelf position, the air flow across the base of the oven may give a false reading.

Regards

David

sarah

I80c is 180c - the lower temperature is achieved by "greater efficiency" because the hot air-flow is almost immediate, and unlike a conventional oven where when you open the door and put the cold food in the temperature drops right off, the temperature in the circotherm recovers more quickly.

The temperatures given for cooking food in a domestic oven are based on the shape of a thermal curve - the setting you make, i.e. 180c, is the point where the input of heat will be cut off, i.e. at the top of the curve.

A steeper curve in a more efficient oven means you can drop the level of heat that the oven has to reach - hope that makes sense.

The two straightforward variables are the temperature setting, and the time setting, the more complicated issue is the thermal curve, which has to be considered when cooking foods of different densities and with different moisture content.

But if those temperatures work for David then they should for you – if not, I would get an engineer to call and have a sponge cake mix ready and waiting to show him the problems you are experiencing

Thank you both. I have just moved the thermometer up to the middle shelf and set the oven to 200 - the thermometer just about reached 200 so I dont think it was making any difference it being on the floor of the oven. I will try the cake experiment and also have a go with David's conversion table.

Thanks again

hi i have a Neff cirotherm oven for 3 half years now and find it very controlable, you have to think 180 normal oven is 160 on the circotherm , and adjust the number to the temp required for convetional ovens, so, 190 is 170 and 200 is 180 and etc, i cook every thing on 160 except roast tatties then i need on circotherm oven a temp of about 180,for 200 and 200 for about 220 for yorkshires.

Hi again sarah

I found this graph which I posted for Lisa in June 2007, as she was also having problems with the circotherm - I notice that you also posted on that thread, but at the time you were waiting for your oven to be fitted.

It's only the "oven simulation results graph” that I am referring to, as it may help to explain the point I was making above more clearly.

The graph illustrates the way the temperature rises in different foods, i.e. with meat, the rise is gradual and plots a fairly straight and progressively rising flat line (the pink and yellow lines on the graph).

Whereas with bread, the rise in temperature happens more quickly and the heat curve is much steeper (the brown and purple lines).

If the curves become steeper because the oven provides heat more efficiently and quickly, consequently the cooking process becomes more advanced, and the temperature can be lowered.

In a conventional oven, the chamber has to be heated to the desired temperature, which involves raising the heat levels in the various metal structures of the oven, and then there is a heat loss when the door is opened and the cold food is introduced. So an oven that was at 180c may then fall back to say 120c, it then has to increase the heat input in order to aim for the heat setting governed by the thermostat, i.e. the temperature set on the cooker dial. With bread it will achieve the set temperature relatively quickly, whereas with a large joint of beef, the heat penetration will take much longer and the thermal curve will be much flatter.

[link]

The problem with the conventional method of cooking meat in an oven (circotherm or otherwise) is that by the time the middle is cooked, the outer section is very overcooked because the outer 50% of the joint has been at a high temperature for much longer than the inner portion.

Hence Heston Blumenthal's ideas of cooking a joint of beef at low temperature for around 20 hours - the time scale and low temperature setting allows the heat to cook the beef in the middle without subjecting the outer 50% to high levels of heat for long periods. Such a process also allows the collagen within the joint to be broken down without drying the meat up.

A strong selling point for the circotherm is that it is saving energy by bringing down temperature settings, but I really wonder just how much energy is saved, when all factors are taken into account – for example, raising and maintaining the hot air-stream is bound to use up a considerable amount of energy. To my way of thinking its rather like accelerating hard in a car whenever the road is clear in order to bring down the average time and top speeds when making a journey from A to B. The Ferrari driver may be able to claim that s/he never went above 50 mph, but the lower top speed was achieved by the use of more fuel due to the power required for rapid acceleration whenever possible.

The ultimate test would be to cook two identical dishes and clock the energy consumed by the circotherm and a conventional electric oven.

But anyway, I hope it works out OK for you sarah – all the best.

Hi Again Gastrosurf

Ah, yes I remember posting on that thread now and giving the lady some advice on how to deal with the people who (mis?) sold her the oven...

Thanks so much for taking your time to investigate this subject to this degree - your explanation, along with the graphs make perfect sense...Sesley also gives the same advice as David re equivalent temperatures so I will give that a go tonight when I am cooking my partner's birthday meal

thanks again Gastrosurf and all the best to you too.