On Sun, 17 Feb 2008 08:30:34 -0700, "Donna Ohl, Grady Volunteer
Coordinator" wrote:

On Sun, 17 Feb 2008 07:26:23 -0600, Vic Smith wrote:
If your pipes are galvanized you don't need di-electric fittings.

Hi Vic Smith,
THIS IS MY BIGGEST CONFUSION!
I see only *some* of the hot water heater replacement guides saying to use
the di-electric fittings while others ignore it totally. Our existing
plumbing has galvanized connected to flex tubing connected to nipple on the
hot water heater.

Di-electrics are used when collecting copper to steel. Newer homes
usually have all copper. Di-electrics usually come into play when
replacing the main service (the bigger supply lines) from galvanized
to copper, but leaving the plumbing wall galvanized pipes in place.
You would use a di-electirc union between the copper and galvanized.
I've never used flex on a hot water heater, but suppose that flex
connectors have the di-electric insulator built in. Should be some
specs attached to that type of connector.

You may find some of the old pipes/fittings scaled up and need
replacing. Same with stop valves. This is the time to replace old
questionable stuff.

We agree. Strangely, the cold-water pipes are all full of crusty white
baking-soda like crud while the hot-water side seems relatively free of
scale. We're still replacing everything, including the old round green
twist gate valve, with newer better plumbing like the red lever ball valve.

The hot and cold pipes could be different ages, or the mineral content
could precipitate differently that what has been my experience, which
is the hot water scaling up much more.
I wouldn't use a ball valve as a stop valve. For long term use I
believe a typical globe or gate valve will prove more reliable.

--Vic