We have a coffee maker with an insulated jug. It is a great idea, as it uses less energy to keep the coffee hot, and there's less chance of it burning the coffee.
I filled the jug with cold water, poured the water into the coffee maker, put a filter in, poured coffee into the filter, slotted the jug under it and switched it on.
I returned after 5 minutes to pour myself a lovely cup of coffee, to find a coffee-ground flood all over the worktop.
The jug has a lid with a sprung valve, which needs to be screwed on, or the bottom of the filter holder remains closed.
I repeated the brewing, this time making sure that the lid was screwed-in. I stood by the coffee maker, to make sure that it was working correctly.
It worked! I had a jug of coffee! I tilted the jug, to pour the coffee out, but nothing happened. The lid was closed, so I screwed it to the "open" mark and tried again, Coffee poured into my cup, followed by the lid splashing into it, spilling most of the coffee out! It seems that the sprung loaded lid just needs to be pressed to allow the coffee out.
And people wonder why I prefer instant coffee!