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?

In article . com,
writes:
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?

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.

--
Andrew Gabriel

wrote:
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?

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.

Merryterry wrote:
wrote:
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?

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.

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

On Jan 7, 1:15 pm, wrote:

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

AG's post is right.