How to replace this shower valve?

[blackhat]

Give a shake on the shower arm. If it's mounted securely, ie, screwed to some wood backing, all you have to do is cut the riser to the shower head. A shark bite coupling there as you put the new valve in. The other lines should unscrew from the old valve and into the new one. Easy peasey.

[Robert Adams]

Those cpvc threaded connections aren't compression they are garden hose connections... 


   I would just cut it out and replace. New glue fittings to the cpvc and either shark bite, compression or sweat fittings to the shower and tub spout. Very easy replacement since you are lucky enough to have access which is rare. 

       Usually when i do a replacement its always cutting out tile and then carefully patching and retiling around the fixture.

[Mr_Mike]

All except the shower head are easy. The supplies, I'd just redo in PVC unless I was going all the way back to the supply with PEX (I'll actually be doing this in my retirement home.) The spout, cut the vertical in the middle and use a straight coupler to reconnect the stub you removed and attach to the new valve. You need to take an additional 1/8 inch or so out of the length due to the coupler's internal stops.

For the shower head, I'd cut the vertical about two inches from the valve and use a stopless coupler. Stopless couplers slide over one pipe and then you position the mating pipe and slide the coupler in position. Just make sure its centered.

Fiberglas tub protection: Get a heat resistant cloth used for the purpose. I'd not risk getting the surround hot by using galvanized sheet metal. Normally, I use 1/4" hardiboard, but I have it laying around. If you have nothing, just by the fireproof cloth. Also, use MAP gas. Its hotter, thus reducing the time the torch is on and reducing the likelyhood of damaging the tub surround.