Expansion tanks, trapped air

CBRob

I think all of these tanks are allowed to be installed vertical. How would the trapped air ever get out?

EBEBRATT-Ed

With a bladder tank there is always air on one side of the bladder and boiler water on the other side. The expansion tank acts as an air cushion to keep the correct pressure in the system.

Wit a bladder tan you need automatic air vents or manual air vents or a air scoop or microbubble eliminator to remove the air from the system.

CBRob

Wouldn't air be trapped under the bladder when the threaded end is down?
I've always installed them threads up.

Intplm.

CBRob said:

Wouldn't air be trapped under the bladder when the threaded end is down?
I've always installed them threads up.

Nah. After some time the water will absorb the air if any is there at all.

hot_rod

thread up is preferred, thread down or horizontal are acceptable, according to Zilmet instructions.