Plumbing – Replacing galvanized

Copper pipe should be self supporting for the height of a room as long as you clip it as close to the floor/ceiling as possible, but if you've got particularly high rooms or high pressure you still might get some banging.

There are various types of pipe clip you can get, some screw into the wall others nail, you just need a suitable anchor point.

1/2" (15mm) pipe should be adequate for most purposes, but I'd go with the size closest to the current pipes. Bath taps (in the UK at least) usually have larger diameter (3/4") to basin taps (1/2"), so you might want to use 3/4" (22mm) pipe if you've got a large bath.

The short answer: you should replace the relief valve.

The long answer: In general, you should not attempt to repair any pressure relief valve. This valve is the only over-pressure safety in the system. This should only open if there is a blockage in the system (causing a pressure buildup), or if filling the system with a faulty pressure reducing valve.

Normally these valves fail due to calcium build up on the interior, which is hard to avoid without having a water softening system installed.

I would recommend changing out both the pressure relief valve, and the pressure reducing valve, as it appears to have quite a bit of calcium build up as well (and may have a small leak). To have both replaced would generally cost in the range of $200 to $500, depending if you replaced them yourself or not. If there are no other leaks or issues with the system, changing both of these valves will solve your zero-pressure issue.