If you have even a small amount of plumbing experience, it is not necessary to call in an expert for a simple job such as changing out a shower tap. Most shower taps today are designed with three knobs: a hot water knob, a cold water knob and a knob to change the water flow from the tap to the shower. Because these knobs attach directly to connections behind your shower, replacing this hardware is much easier than it was in the past. 

Instructions

1、Turn off all of the main water supply lines to the bathroom where you are replacing the tap.

2、Open the access panel to your shower (usually located in the side of your linen or water heater closet, whichever is closest to the tub/shower). Clamp one adjustable pipe wrench onto the main pipeline and tighten it. Hold this wrench in one hand while you loosen the tap hardware from behind using the second wrench. Carefully pry and lift away the old hardware and dispose of it. A small torch may be required to melt the old putty around the main faucet if it is very old and/or shower taps hard.

3、Use a measuring tape to measure the openings left once you've removed the knobs and main tap. Write these measurements down. Visit a hardware store and pick out a new assembly that is constructed similarly to the old one and has components that match your measurements.


4、Install the knobs from behind by pushing them through the opening. Use one pipe wrench or your hand to hold them firmly in place while you use the second pipe wrench to screw the threaded pieces of the knobs and the threaded pieces of the main pipeline together securely. Wiggle the knobs with your hand to make sure kitchen taps they are attached well.

5、Apply a small amount of plumber's putty around the opening for the main tap. Slide the tap into place through the front and press it into the putty securely. Apply more putty around the tap if needed to seal it completely. Move behind the tap, to the access panel, and use a pipe wrench to tighten any remaining connections.

6、Allow the putty to dry completely (overnight is best) before using your new shower tap.

http://www.plumpinguk.co.uk/blog