But not our new one. No glug, no hiss.
Before returning it, let's see it it's easily fixable.
The lack of glug is the key clue - the valve isn't letting water into the heating chamber.
Here's the valve. It's inside the tank-fill-cap.
|Valve doesn't work||Correct|
Looks like it was assembled improperly - the stem fills the rubber hole, not allowing water through...but looks are deceiving. I suspect the rubber seal isn't supposed to be inside the hole at all, but a sealing cap on top of the hole.
Use the stem to gently poke the rubber seal out of the hole, and suddenly the seal's size and shape make more
sense. And it even seats on the stem properly.
Best of all, now it even works.