Did you install a dielectric union /nipple to prevent galvanic action between the ferrous metal of the H / W heater and the non ferrous supply piping?

If not then here lies your problem

TO: sylvan

Thanks for the reply to my question. I have flushed out the hot and cold water supply to the shower, where I had the problem. It is now working great.

Question: How would I recognise a dielectric union/nipple? If not on the hot water heater, can I purchase one at a local plumbing supply store and install it myself?

Thanks, golfwally@comcast.net

A dielectric fitting nipple or union and is used to prevent electrolytic action between dissimilar metals like ferrous and non ferrous copper as opposed to galvanized steel.

Installing one yourself would depend on how handy you are if soldering is required or if the existing piping is screwed.

Also if you have to solder extra care has to be taken not to solder within 6" of the tanks inlet and outlet as you can destroy the plastic parts inside.

Also the dielectric fittings have insulators to (plastic / rubber) that also must be kept away from excessive heat (torch)

There are to many variables to give you a quick yes you can do it yourself of not.

Many DIY folks fail to take the precautions of shutting off the water supply and gas / electricity and do not think about letting the water cool before working on the tank.

Depending on the age of the tank sometimes you have to figure if it is not broke don't fix it.

If the tank is less then 2 or 3 years old I would consider having the fittings installed again depending on your water quality Ph factor etc.