Why Doesn't My Hot Water Last When I Shower?

Q: I have a problem with hot water in the shower. The hot water comes on quickly, but it seems to shut off after about only three minutes. I have changed the faucets from the pipes without any results. Only the shower seems to be affected. What is the problem?

A: If your hot water only comes on for a short period of time, it sounds like you may have a problem with your bathroom shower valve. The possibility of a stoppage in the copper piping system is remote. Unlike older galvanized steel pipes, copper pipes rarely corrode on the interior of the pipe. Therefore, other than some minor oxidation, the pipes stay free flowing.

When the rubber parts in the shower valve get worn and distorted from old age, they can also swell up causing restrictions in the waterways of the valve. This swelling increases as the temperature of the water traveling through the valve increases.

It's not uncommon for these rubber parts to also break off from the valve components and travel into an orifice or port in the valve.

At this point you or your plumber will have to flush out the valve, remove any debris, lubricate all moving parts and replace all worn components and washers.

A word of caution: The body of the shower valve is hidden in the wall, and not readily accessible, so care should be taken not to cause any damage to the valve body.

Unlike a kitchen or sink faucet, replacement of the shower valve is much more difficult and requires a higher level of skill. It is best to let a professional plumber handle this. Click here if you need plumbing repair.

Vince McDonald, McDonald's Plumbing, Heating & Air Conditioning, Sacramento, CA