A master plumber shows the fittings and techniques used to make leak-free connections between copper, PEX, CPVC, galvanized steel and more.
By the DIY experts of The Family Handyman Magazine:July/August 2013
Les Zell has been a plumber for 30 years. Many of his customers
have several different types of pipes in their homes,
and the number of different kinds of fittings he carries in
his van has tripled. Knowing how to join dissimilar pipes
has been essential.
When you go to add or replace
plumbing lines in a house that's
more than 10 years old, chances
are you won't find new pipes that
are the same kind as the old
ones. That's no big deal—hardware
stores and home centers
carry hundreds of different kinds
of transitional fittings to help you
make the connections. What is a
big deal is that those hundreds of
different kinds of fittings don't all
install the same way.
Some fittings need to be soldered;
others take just a wrench
or pliers. Several require specific
crimping tools, and there are
newer styles that simply push
together. We asked a master
plumber how he deals with the
ones he encounters the most, but
don't run all over town trying to
find the exact fittings we show
here. There are usually several
suitable solutions using parts
available at a local hardware
store or home center.
Installing a brass compression tee body
is a good way to provide water to your
refrigerator's icemaker. Although the
brass ferrule seals the copper pipes to
the tee, Les still uses a little pipe dope on
the ferrule to assist in even compression.
Many municipalities don't allow 1/4-in.
icemaker lines to be covered by finished
walls, floors or ceilings, so you may have
to run a 1/2-in. line to the fridge instead.
This angle stop adapter
valve is a great solution
if you want to install an
water filter. It fits
between the shutoff
valve and the braided
line that runs to your
faucet. No pipe dope or
pipe thread tape is necessary
washers seal the
If you want to connect PEX to
copper by soldering on a
transitional copper fitting, make
sure you wait for the fitting to
cool before attaching the PEX.
The downside of PEX is that
many of the connectors are
proprietary, and it's extremely
important that you use
Use this link for more information on connecting pex to copper.
Les likes to work
with the brands of PEX that can
be connected with cinch
clamps. Just slide the cinch
clamp over the PEX tubing, and
then tighten the clamp with a
cinch clamp tool. Cinch clamp
tools are sold at home
It doesn't get much
easier than this. Glue
the CPVC end (there
is a band of CPVC in
the female end of
this copper fitting),
and secure the PEX
with a cinch clamp.
Let the glue fully cure
before turning the
water back on (some
CPVC cements require several hours to cure).
Use this link for more information on connecting pex to cpvc.
The inside of galvanized pipes gets thinner over the years. And the male ends, where
the threads were cut into, can become so thin that they leak when you try to screw
on a new female fitting over the end of them. So try to make the transition at an
existing female fitting.
When working with galvanized pipes, Les wraps pipe thread
tape on the threads and dabs on a little pipe dope as added insurance against leaks.
connecting ABS to
PVC drainpipes is
to use male and
Apply pipe thread
together, and then
glue the pipes into
the fittings using
the proper cement.
Arrange the fittings
so the water flows
past the threads
on the male fitting,
not into them.
This helps solid
materials flow by
Use this link for more information on connecting abs to pvc.
Plastic and metal expand and contract at different rates. This can be a
problem when joining CPVC to copper, especially when using threaded
connections. One option is to use union adapters. The rubber washer
should flex enough to keep the connection sealed.
Use this link for more information on connecting copper to cpvc.
If you choose to solder the copper side, make sure you do that first or you’ll melt the plastic side.
Save yourself repeated trips to the home center or
hardware store by taking a small chunk of each pipe
you plan on using to the store.
want you to
show them that
materials. If you have to
choose between two similar
products, buy the one that is
clearly labeled as being approved
by nationally recognized organizations.
ANSI and ASTM are
examples of widely accepted
product certification organizations.
And save your labels until
after the inspection is completed.
For more information on what
these markings mean, check out
These couplings are
often referred to as
and they work great
to connect dissimilar
drain lines: galvanized
steel to plastic,
cast iron to plastic,
ABS to PVC.
sure you use a fully
because the couplings
with just the
two individual hose
clamps may not be
allowed in some
Connecting two dissimilar metals can
cause galvanic corrosion, which deteriorates
metal over time. A dielectric
union is a fitting designed to isolate
the two metals from each other. There
is some controversy as to the effectiveness
of dielectric unions, but the
bottom line is that if you connect a
copper pipe to a galvanized one, some
plumbing inspectors are going to
require one. Certain municipalities
consider a brass fitting a suitable dialectic
union, but others do not. Your
best bet is to ask your local inspector.
Use this link for more information on connecting copper to galvanized.
Push fittings haven't been around
all that long, but they are without a
doubt the easiest way to join two
pipes. Even though push fittings are
easy, you still have to do your homework.
Read the instructions on the
type of fitting you're using to see
how far the pipe needs to be
inserted, and make a mark on the
pipe at that length to ensure that it's
pressed in all the way. And be certain
that the outside portion of the
pipe that will slide into the fitting is
free of burrs and scratches.
When Les joins dissimilar
pipes, he likes to install a
control valve whenever
possible so the water in
the rest of the house can
be turned back on while
he's making his repairs.
Some control valves are
designed to be transitional
fittings, but most
can be converted by
adding various fittings at
Just because a fitting is the right size or configuration
doesn't mean it can be used in any situation. Some can be
used above ground but not below. Others work perfectly
fine in the open but can't be buried behind drywall. When in
doubt, ask your inspector. Here are a few examples of connectors
that may seem like the perfect solution but could
be rejected by your inspector, or worse, fail to work and
cause thousands of dollars in water damage:
Dresser couplings: These will pull apart on pipes that
aren't completely immobile.
Quick elbows: Drain snakes can poke right through them.
Saddle valves: These valves are not always allowed. They
clog easily and don't always shut off reliably.
No-hub mission couplings: These couplings are for cast
iron to cast iron connections only.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
You'll also need a cinch clamp tool.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.
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