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Notice for TM5 users - Temperature reading

Posted by Bee & John on March 24, 2015 at 4:35 AM

TM31 owners..... no need to read further :-)

TM5 owners, listen up!

I did a delivery yesterday to another excited couple, luckily (as it turned out) they were SO lovely I'm sure they'll forgive me for doing what I THOUGHT was my job, but actually, I was wrong (DON'T tell John... he knows very well I am NEVER wrong!!  In fact, I'm having cold shivers just thinking about being... you know... that word.

The problem was,  I was doing my normal  heating of water & vinegar.  This is where I familiarise the new owners with the controls and checki that the Thermomix is heating like it is supposed to.

ANYWAY....  THIS time I checked the temperature it was registering at the end and it only heated up to 98. I could NOT get it to heat up higher... I could SEE that the water was BUBBLING higher if the temperature was set to 110oC, but the temperature it was actually reading from the bowl was only 98.  I apologised red-faced and had to pack the machine back up and took it home with me.

Um..... does anyone see the obvious flaw in my assumption that something was wrong?  Water only reaches 98-100oC when boiling.  It might BOIL faster, create more steam, but it actually only REACHES 98oC - 100oC   Yes, in some instances it can boil at 98oC!  WHAT?  Yup... For a start, if it isn't EXACTLY 100oC it will drop into the next lowest temperature... 98oC.  And.... scientifically boiling point is "The normal boiling point (also called the atmospheric boiling point or the atmospheric pressure boiling point) of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level" (Wikipedia) - that all means that it depends on the altitude and the airpressure in the room.

But..... is that true?  Well, it sounded ok but I couldn't get my head around it..... so I got my machine out to test it.  Now I KNOW my TM5 is working right because not only have I used it extensively at all temperatures, but I have also used BOTH the TM31 and the TM5 together making the SAME thing - litres and litres of Plum Sauce - which I cooked at Varoma on both machines - they BOTH gave the same result in the same amount of time.  I never thought to see what temperature the TM5 was actually READING, just trusted it that it would do what I asked it to do when I set the temperature.

So, as I said, I tested MY machine to see if I can get a different reading with water and vinegar.  Nope, it actually only went to 98oC - although it was VERY clearly boiling.  Then I tried Varoma temp.... As you can see by the video on my facebook page (it won't load here) as soon as I take it off "Varoma", it goes back to 98oC.  Now... WHY is it reading 98oC?  Does that mean that your machine is not heating up properly?  

NO - it all comes down to the temperature setting is for the HEATING ELEMENT at the bottom of the Thermomix bowl and the temperature it is READING (that little temp at the top of the circle) is the TEMPERATURE OF THE INGREDIENTS.  So.... if the ingredient's boiling temperature can't get higher than 98oC, then it won't READ any higher.  But the higher setting is used to agitate the liquid faster, crate a browning effect or to create more steam (for steaming or to reduce the liquid - maybe even both).

So, if your temperature reading (at the top of the temperature dial) is less than the temperature you SET, don't panic - the heating element HAS reached the right temperature, but the ingredients can not actually GET to that temperature, that temperature just has an other effect (like the excess steam)

My punishment for my erroneous assumption something was wrong?  I'm driving 100ks tomorrow to take the Thermomix back to the waiting owners.... and 100ks back again.  Just as well it's a lovely drive and I have a great Audio Book to listen to :-(

Any more questions.... contact your consultant.  If your consultant is ME... ring me and I'll have a chat :-)

Categories: For your interest, VERY useful information