Purpose of Hole in Moka Funnel I recently switched from a Bialetti Moka Express 3-cup stovetop espresso maker to a Cloer 5928 espresso maker. It has an integrated heating unit, just like an electric kettle, so making a coffee is now much more energy-efficient.

The coffee from the Bialetti was flawless (using a medium-fine grind of Starbucks espresso roast beans). Now I have a difficult time producing coffee that is not both overly thin (underextracted) and has an odd taste that I can't even describe (perhaps from overheating the ground coffee?). 

The new espresso maker takes some time to heat up (365 Watts of electric power), and then the coffee is pressed through relatively quickly in short bursts. 

Having a look at the funnel, it has a hole, unlike the funnel of the Bialetti. My questions are:


Can the hole in the funnel have anything to do with the underextracted coffee?
What could be the purpose of the hole anyway?
Just guessing here, but the hole could keep the water from going up until it reaches a certain temperature. The amount of pressure from the steam varies on the temperature of the water, and if there weren't enough pressure, the water would recycle. However, if the pressure were greater, the velocity of the water would prevent it from dripping out of the hole.

This could explain the bursts, since the pressure would rise and fall depending on the amount of water it pushed out. The more water that escapes, the more room there is left behind for pressure to fill.

Also, you mentioned a weird taste. Could it be metallic? If so, you could try letting the base sit in a strong coffee/water mixture for a couple days. The moka pot needs to be seasoned to prevent this taste, so I would recommend not washing it with soap - just rinse. My grandmother has never washed hers.