Hot water tank pipe functions

[bc962358]

Attached is an image of the gledhill combi tank in my newly purchased flat.

I can't work out what the second pipe going into the top of the tank does, and cant find any info on the internet.

Please can someone advise?

I think its a Gledhill economy 7 direct combi tank.

Many Thanks,
Joe

 

[chris watkins]

The one right at the top next to the 15mm mains water supply with the stopcock is a 3/4" Overflow run in 22mm copper. The one lower down (Mid way) is the hot water out also in 22mm.
I like the drain off at the bottom Joe.
BTW welcome to the forum.