How do I replace a shower/tub faucet?
First of all, if you can possibly replace your cartridge, and be satisfied with your existing Moen valve, your problem is going to be 1% the size of re-fitting a new valve. You can get common Moen cartridges like the 1225 B, which is used in many Moen shower sets like the 2205 for under $20, and even the special little white plastic tool you need for changing them is included (as sailormouth mentioned – the chrome tool sailormouth linked is generally for maintenance people or plumbers who change a lot of Moen cartridges, and don’t want to fool with the little plastic thing). You can be in and out of this repair in under an hour. The Moen site also has a great valve model identifier page, and you can order parts direct from Moen, if your local plumbing distrib
