zone heating /cooling work station

[Lc_shi]

Hi Sirs

I attatched a photo of one zone heating /cooling work station.
I'm not sure what valve it is between safety valve and pressure tank and what function it plays. who can teach meabout it? thanks in advance!

rgds
lichuan

[Lc_shi]

sorry attach again

[botrous]

I agree with Mark , it should be the service valve for the expension tank , it is used to isolate it from the system in case of maintenance or replacement work.

[Brian_UK]

The main valve is an isolation valve to allow for servicing of the expansion vessel, the second, downward facing valve is a drain valve.

You would need to isolate the expansion vessel to check the cold fill pressure etc.

[Peter_1]

It's correct but don't forget to re-open it afterwards.

[Brian_UK]

It's correct but don't forget to re-open it afterwards.

Yes Dad..

Good point Peter; there goes next weeks call back

[Lc_shi]

thanks for your good idea.
the valve is a integrated one (with both cut off / drain function). I've taken the point.
will invite you to have tea while you come China


rgds
lichuan