Thrush valve maintenance?

nicholas bonham-carter

About to do the yearly draining of the compression tank.
Is there anything needed on the Thrush valve?—NBC

WMno57

This Thrush valve?

https://heatinghelp.com/assets/documents/221.pdf

My system has an additional isolation valve between the Thrush valve and the compression tank. I'm not sure the isolation valve is needed.

Reason I say that is I recently had my compression tank replaced (pinhole leak) with a like compression tank. This was done with a full wet system, and the thrush valve held back the water.

JUGHNE

WM, did you have a isolation valve on the return line at the pump?
It seems you would have to stop the water from draining out that way.

WMno57

This is on the return, but the flippers are stuck, so it hasn't changed in years.


No isolation valves by the pump either.


Maybe a partial vacuum in a second floor radiator held the water back?

mattmia2

So it is just a flow check with an air scoop on top of it?

Big Ed_4

Thrush made the best valves , as you can see they last forever ... I never had to clean one ...

WMno57

mattmia2 said:

So it is just a flow check with an air scoop on top of it?

I guess so. It works great. I went two entire heating seasons without draining the compression tank. No Airtrol on the tank either.

Big Ed_4

Not exactly an air scoop but the tap for the expansion tank is just below the check flap . Any air that migrates down and collects as a bubble would rise back up into the tank ..