: Ok thanks. So the potential air pressure in the line is ok?
: : The best way is to put a cap on the water outlet and then make sure the faucet is turned on. That way you also test the joints up to the shower arm connection, including the plug for the unused tub connection if your valve had one. If you have a leak the air will come out on its own through the leak.

: : : We are remodeling our second floor bathroom and I just installed the shower mixing valve. I wanted to test all my joints before I put the walls up. I do not have the trim/handle for the valve yet(on order) so I would need to open the valve (gently) with a pair of pliers to let the air escape - then close the valve after the air leaves the line? Is that the correct way to test? Am I correct to assume that I cannot just turn the water on (the line is currently shutoff in the basement)? Thanks for the advice.