How to replace this shower valve?

[atgcpaul]

This is the back side of the shower/tub my kids/guests use.  I want to upgrade this to a nicer Delta mixing valve that we already use in our master bath.

It's easy enough to disconnect the supplies, but I'm scratching my head on how to disconnect the lines to the shower head and the tub spout.  As you can see, the original installer used pipe dope to seal the threaded connections to the body.  I've confirmed on the valve I removed from the MBR that with enough force I can loosen the connection, but it wasn't in the wall at the time.  The connection at the top near the shower head is surely screwed to some wood (I'm guessing, but it was in the MBR) so it's not going to spin.

I'm thinking to cut the pipe going down to the tub spout and replacing it after the new valve is in.  I might have to cut some pipe later anyway depending on the new valve.  Any other ideas?  I'm a soldering novice so I'm trying to avoid getting a torch in here if I don't have to.

   

[Phil Thien]

Those are compressing fittings right? Just back the nuts off with a wrench?

Oh wait no. Not compressing. I think you will need to cut those.

[Bob10]

Cut all 4 pipes use these to repair the 2 you are having trouble with 
I have to tell you sweating joints is not rocket science.  Look at youtube and practice some before the main event.  I use some flashing to protect whatever I am worried about near where I am soldering.  The valve can be done on a bench away from the shower stall.




Thought about this some more and you could use a valve like this with threaded connectors with compression fittings

[chips ahoy]

When I installed my new shower,no tub,I screwed in a plug where the tub was to be used.On the two supplies,hot and cold I installed unions and also a union on the shower outlet.To change out the valve, I just shut off the hot and cold water,unscrew the unions,remove the valve,install new valve with the unions screwed back in place,join all three unions and turn the water back on.I made an access hatch behind the shower to have easy access to the back of the valve.Hope this makes sense.

Mel

[Snipe Hunter]

If it makes you feel better, whoever installed that one was a soldering novice too and it's still working.

[Bill Bob]

I vote for PEX connections. 
Bill

[gMike]

Another vote for Pex as the quickest way to get this done.

[Bob10]

Funny I saw the mess of a soldering job and assumed it was soldered in.  Never looked closer but thought it odd that the other 2 were threaded, it was a long day should have paid better attention

I have to ask how do you stabilize a pex connection at a location like the the tub spout or shower head? from what I have seen the connections spin

[efmrrt]

  I'm a soldering novice so I'm trying to avoid getting a torch in here if I don't have to.

This is the best way to learn to use that torch! 

Replace the pvc pipe. PEX is the way to go, its a more expensive route too.  The PEX tubing is cheap - its the fittings that $$$$. Biggest things to know when using PEX is to get all the burs off and seat it well. Use red PEX for hot and blue for cold. After you get all the parts, you'll have it done in < 30 mins.

[Roly]

If you go the pex route do not use pex for the tub filler piping.   The smaller ID of the fittings will force the water up to the shower head when you do not want it.    Roly