Thermos Flask Stopped Working

Redlander

I bought a fairly pricy Thermos flask (I am using Thermos to denote the actual brand, not as a generic term) a little over a year ago and it has suddenly stopped working. The outside now becomes warm to the touch as soon as it is filled, and on opening it a couple of hours later the drink is luke-warm. However there is no perceptible damage nor any leakage.

What kind of fault might have occurred. Do vacuum flasks usually have such a limited working life?

On checking the instructions I saw that bleach and chlorine-containing substances must not be used, and I have been in the habit of cleansing it with Boots sterilising fluid. Could that have been what caused the damage?

MysteryMe

Might be covered by this? https://thermos.co.uk/warranty-returns-policy#optionc

I'd contact Thermos customer service, the email is on their website

fatbelly

I have a flask that went the same way. I think the vacuum gets lost - nothing to do with sterilizing. 

I still use it alongside one that still works. So if we go out for the day, the defective one is good for a hot drink mid-morning and the functioning one is too hot to drink until lunch/afternoon!

Eldi_Dos

If your flask is a stainless steel version and the cleaning solution contains Chlorine that is most likely the cause.
A reaction happens which breaches the vacuum, check on underside of flask for any warning that may be on it.

twopenny

I have one that's over 50yrs old and still working - unless they made them better in the old days

Something to look at is the bottom of the actual thermos if it's glass in a shell. There used to be a point where the glass had been 'finished' and it rested in a nest at the bottom. You used to be able to unscrew the base and check it was intact. If it's been damaged it's possible for the outer layer to be pierced but not the inner so breaching the air gap.

You could also get a replacement inner vaccum

The very modern steel and such are made to be streamlined and rather than replacable parts and imo don't do so well at keeping things hot or cold.

chrisw

twopenny said:

I have one that's over 50yrs old and still working - unless they made them better in the old days ;

Until you took it out of your bag and it sounded like a cocktail shaker full of crushed ice.