Draining expansion tank?

[theflyingpig]

If I want to drain the water out of an expansion tank do I hold down the valve on top to let air in?
I've got a preassure guage so can recharge the tank I guess?

Thanks!

 

[flameport]

Leave the water connection open (or the system it's attached to open) and then pump air into the valve.
Keep pumping air in until the pressure reaches whatever is required.

 

[theflyingpig]

Leave the water connection open (or the system it's attached to open) and then pump air into the valve.
Keep pumping air in until the pressure reaches whatever is required.

Ah ah, thank you!

 

[theflyingpig]

Couple of buckets full came out, but then it doesn't seem to hold any pressure.... Knackered?

 

[DP]

Couple of buckets full came out, but then it doesn't seem to hold any pressure.... Knackered?

On the expansion vessel, when you pressed in the pin on the valve, did water squirt out of the valve?
Pressuring the vessel, ensure the water side pressure is zero at all times by looking at the pressure gauge while air side is being pumped up to setting pressure.
If you hear bubbling noise, the bladder or diaphragm is ruptured
Caution.. heating and hot water cylinder expansion vessels are not interchangeable

 

[theflyingpig]

I didn't press pin on valve - just coinected bike pump and pumped water out. I then assumed I'd be able to repressurise it.... But it doesn't hold any pressure at all.