Temperature control - feels colder that states

[trustyrusty]

Hi I am using fermenting fridge for first time, and is set at 18. But if I put my hand on fv which is SS feels really colder than 18. I have thermometer in fridge to check and is 18 too. So I think everything working fine and is bubbling away. Just feels much colder, is it just me. Today is about 20 deg. So not hot and big range from outside to inside fridge. Do other of you feel the same. It real feels like 4 or 5 deg but maybe because it is stainless steel fv? Cheers

 

[Grott]

I’d say it’s because it’s stainless and your hand being warm would sense a vast temp difference bigger than actual. If fermenting away I’d say all ok.

 

[trustyrusty]

Yep thanks, probably that's it...

 

[warra48]

Your blood pumps through your body at 37 degrees C. No wonder stainless at 18 degrees feels cooler than ambient! All good, no problems.

 

[Feldon]

Try putting your hand on the plastic wall of the fridge (away from chilled refrigerant coils buried inside the wall if you can). I bet the wall doesn't feel as cold as the stainless fermenter. This is because the nerves in your hand don't sense temperature. They are not thermometers. What your nerves sense is the rate of heat transfer from your warm hand into the colder stainless. The faster the heat is transferred out of your hand the colder it will feel compared to touching a surface that has a lower rate of heat transfer. Stainless is a better conductor of heat than plastic so the fermenter will 'feel' colder than the plastic wall.

You'll experience the same thing if you put two bottles of beer in the fridge, one glass the other PET plastic, and leave them a long time so both reach the same cold temp. Grab hold of them and the plastic bottle will 'feel' warmer than the glass bottle - but its not. Both are the same temp.

 

[Lyrebird_Cycles]

Thermoreceptors respond to local temperature at the skin, which has a component that is due to rate of heat loss / gain vs homeostasis* .This means that if you place your hand on a piece of a material which is a good conductor of heat (like most metals**) and is significantly above or below body temperature your thermoception will overestimate the heat difference: we didn't evolve in the presence of such good conductors so our senses weren't tuned to them.


* The temperature at the receptor will be influenced by the balance between rates of cooling and warming. If one is provided by contact with a good conductor it can overbalance the other being provided by the body's regulation mechanism (homeostasis).

** Stainless is actually a relatively poor conductor of heat by metal standards but it is still way better than, say, wood.