Hi Guys

Following issues with air locking, I decided to uncover the motorised valve
for the heating system (S Plan).
This has been boxed in in the corner of the dining room (formerly the
kitchen), with the boiler and pump being moved to the other side of the same
wall into the kitchen extension.

Having had problems with pump over etc, I suspected that the CH valve could
be at fault.
I am now faced with other questions.

1. When I push the lever manually to operate the valve, the lever is slack
for half the travel. The resistance is then felt and the familiar whirring
is heard. Is it usual for there to be a lot of slack before the valve
internals move? If I push hard to make the valve open quickly, a rougher
sound is heard. In normal operation, it sounds smooth and fine although
last year some ominous graunching? sounds appeared to come from this
location. The valve is captive in a long(ish) vertical leg with tees etc.
so I presume the only way to remove this will be to cut it out due to
compressions ends and pipe engagement? Is it possible to replace the
internals in situ (the valve body and motor are flat to the wall and between
pipes!)?

2. I have found what I think is a relief valve - teed off from flow line
about 40mm long screwed, circumferential holes about half way along and a
screwed cap. Broggling in one of the holes I feel/hear what may be a
spring. The thing is that this is on the flow side from the boiler *after*
the heating zone valve. The boiler is GlowWorm Space Saver 50. Assuming
this is a relief valve, does its position make the installation unsafe?
There is an open vent to the header tank as well (hence pump over mentioned
earlier).

3. Is there a recommended (or mandatory) distance from the boiler that
pipework must be run in copper? I am considering increasing the mains size
to 22mm for upstairs rads and might take the plastic option.

TIA

Phil