Multimeter thermometer probe and electric oven

[David]

I've finally got round to using the thermometer probe on my multimeter to check the temperature in the oven.

The difference between the probe and the oven thermostat is so great that I'm wondering how accurate the probe is.

Umm...updating as we get ready to cook....the probe was hanging down near the door and reading low. I moved it to be more central (draped over the rack) and now it is reading higher, but I'm not sure if it is reading the overall temperature or the air flow from the fan.

So where in the oven should the probe be?

Confused as usual.

Cheers

Dave R

[Cursitor Doom]

IIWY I'd check the spec on that probe and make sure it's capable of withstanding oven temperatures, let alone reading them!

[Chris Hogg]

Do some simple calibration checks - a glass of water full of ice blocks, and allowed to stand for ten minutes or so to equilibrate, should read very close to 0°C, and later, stuck down the spout of a kettle that's allowed to boil for a minute or two, but not actually in the water, should read very close to 100°C. That'll at least tell you if the t/C is anything like reliable. In the oven, the fan should keep the temperature fairly evenly distributed. The fan oven I owned several decades ago, drew air in through a central aperture in the back of the oven and blew it out radially over a finned heating element. If you can see and access the existing oven t/c, try and put your probe as close to it as you can.

[David]

Well, yes, up to 250C continuously or 350C for short periods.

Known as RTFM.

Which I did.

[ARW]

In the food.

[Roger Hayter]

That is if you want to tell if the food is cooked; it doesn't measure the temperature of the oven.

[alan_m]

Also if the battery within the Multimeter is failing it could give a very erroneous reading. If the multimeter doesn't have battery cover you will have to split the casing. The battery is often a pp3, 9V battery.

[Brian Reay]

Indeed.

A probe placed, say, in a Turkey, should indicate 82C when it is cooked. However, the oven could well be at 180C or more. If the interior of the Turkey was at 180C it would be over cooked, to put it mildly.

[newshound]

+1. with that range it could well be a thermocouple, IME they are normally accurate to a degree or two, much better than an oven thermostat. I have put a standard K type thermocouple probe into each oven of my range, going to a 2 channel digital display. It is surprising how much oven temperature cycles even though it is a fan oven, and temperatures drop rapidly when the door is opened. I base any serious cooking on the thermocouple readings. (They poke just into the oven space, towards the top on the sides).

[newshound]

I have a cheap ebay thermometer with thermocouple probe for that, very useful. Also I keep the IR thermometer in the kitchen and use that to check things like frying pan temperatures before putting food in.

[harry]

The easy way to check is to put a glass bowl of water in the oven and see if it boils at 100degC setting. Also check your probe the same way (in boiling water) Oven thermostats are notoriously inaccurate, As they age the oven runs hotter than the set temperature

[harry]

It makes no difference. The water and steam are at the same temperature.

[Chris Hogg]

In principle, yes, but it avoids the possibility of the T/C coming into contact with the heating element or heated kettle bottom and reading high.

[Fredxx]

No, salts even in tap water can raise the boiling temperature by a degree or 2. There is also the phenomenon of superheated water.

Steam is going to be much closer to 100C.

[Dave Plowman (News)]

I'd not guarantee that an oven which reads OK at 100C is going to be correct at 180C.

[Chris Hogg]

Well, no, but boiling water is the nearest reasonably accurate and achievable reference point available to the average householder. If it doesn't read 100°C it suggests something wrong with the probe T/C or the multimeter calibration.

[harry]

There is negligible temperature difference regardless of dissolved solids. There is more heat energy in the steam than the water (Latent heat)

[Cursitor Doom]

Lead is easy to get hold of and melts at 327'C which sorts out the top-end calibration nicely.