Nut on CH check valve?

[kenord]

I have a combi boiler with a check valve on the return side of the filling hose. Can anyone tell me what the nut on the side of the check valve is for? Would it leak if not screwed down tight?

[Andrew Gabriel]

It's a double check valve. The nut gives access to the bit between the check valves. I suspect it's so you can test they are both working. It's probably a regulatory thing, as all double check valves have them.

[Merryterry]

Is it a cap rather than a nut?

All filling loops should now be supplied with a cap on either side. This is so that the hose can be removed and both the check valves capped off.

If it is a nut on one or other of the hose ends it will not leak if loose until you use the filling loop.

[kenord]

It's a but in the middle of the check valve half way between the ends.

[Aidan]

AG's post is right.