Plumbing Tips
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This page was last revised on August 19, 2001.
- When deciding what to use for water supply plumbing, your choices are few. The oldest
homes were plumbed with lead pipe, which is a BAD idea. Then threaded galvanized steel pipes
were used, which are still available. Then copper became the standard. Next, CPVC plastic
became available. PVC can be used for cold-water supply. Lately, mobile homes have been
plumbed with "Qest" plastic. My recommendation? Without a doubt, it's copper. Here are the
characteristics of some of these:
- Copper: This has the advantage of being rigid, and resistant to being damaged. It's
fairly easy to repair, and doesn't adversely affect the water it contains. Older copper piping was
soldered together with lead solder, which could leach into the water in the pipe. Now, it's illegal to
use lead solder for these pipes, and there is no dangerous leachate into the water. However, don't
worry too much if you have older copper plumbing. After the first few years, the amount of lead
leached into the water drops substantially. If you're concerned about lead, then simply run the
water for a minute or so before using any for drinking or cooking purposes to flush the pipes first.
Copper also provides an easy way to ground anything in the house and to ground the whole house
itself.
- PVC (polyvinyl chloride): PVC pipe is usually white, and for pressure may be
schedule 40 or schedule 80. However, PVC cannot be used for hot-water piping because it will
warp or even burst. It is also not particularly rigid in small sizes, and can be easily damaged by
pounding nails into the wall or drilling. There is also evidence that it leaches into the water.
- CPVC (chlorinated polyvinyl chloride): CPVC is a sort of ecru, or light tan, color. It
may be used for hot-water plumbing as long as the water is no hotter than 120 degrees or so. It is
not very rigid, however, and is as prone to damage as PVC. Again, it may be leaching into the
water supply.
- Galvanized Steel: Galvanized steel actually is excellent for water-supply plumbing
when it's fairly new. Because of its threaded nature, it's a lot of work and difficult to assemble.
However, when it eventually starts rusting internally, it becomes clogged and must be replaced,
which is a monumental job.
- Qest: Quest is the least rigid of all these types, and has all the disadvantages of the
other plastics. In addition, it is difficult to work with and to keep properly sealed against pressure.
It can't just be glued like the other plastics but relies on pressure-type fittings. I detest the stuff.
- NEVER mix steel and copper plumbing directly; you'll get something called galvanic or
electrolytic action that will corrode both metals rapidly, quickly clogging the pipes. Also, do NOT
use black steel piping; this is intended for natural gas use only. If you need to patch together
copper and steel, then use what's called a dielectric nipple or use a plastic adaptor fitting in
between to avoid the galvanic corrosion.
- When soldering copper pipe, carefully follow these steps:
- Before preparing to solder pipes and fittings, cut the pipe to size and assemble everything to
make sure that it will fit properly. Use a good pipe cutter to cut the pipe, and make sure that it has
a sharp, well-fitting cutting wheel in it. Lightly clamp the cutter onto the pipe, and twirl it around
the pipe in a circular motion. Make sure that you push it straight around the pipe, and make sure
after one revolution, that it meets the first part of the score. If it doesn't, then try turning the cutter
the opposite direction. If you just can't get it to go straight, then you probably have a really cheap
cutter, or it's damaged, or it's got a bad wheel. For cutting existing pipe that's already installed,
use a mini-cutter. Quality in a cutter is actually quite important.
- Use a wire brush, made for the purpose, to clean the insides of the fittings. Turn it in a
circular motion, and make sure that the entire contact surface inside the fitting is brushed and
clean/shiny.
- Use a different type of wire brush, again made for the purpose (combination wire brushes that
have both types in one tool are also available), to clean the outside of the pipe where it will fit into
the fitting, or use plumber's emery cloth. This is a type of sandpaper that comes in coiled strips,
and you just tear some off to use. Wrap it around the end of the pipe and turn it to clean it.
Again, the entire end of the pipe that will be going into the fitting, plus a little beyond that, should
be clean/shiny when you're done. If cleaning old pipe, the emery cloth will work much better than
the wire brush.
- Use a small flux brush (or a corner or a rag, or even a CLEAN finger) to coat both the inside
of the fitting and outside of the pipe in the cleaned area with flux. The flux must be a high-
temperature flux intended for lead-free solder. It only takes a very small amount of flux, but it
should be applied evenly and completely.
- Fit the pipe together. Never prepare more joints than you can solder quickly, but always
solder all joints in a single fitting at the same time. In other words, if soldering a tee, then make
sure that all three pipes going into the tee are being soldered at the same time.
- Using your propane torch, heat the fitting evenly. Play the flame over the fitting, trying to
reach all parts of it. The very tips of the blue cones of the flame should be at the metal. Always
heat the fitting, not the pipe: thus, the fitting is hotter than the pipe, and has expanded more than
the pipe during heating, so that as it cools with the solder, you have a good compression joint as
well as a solder-type metal weld.
- When the solder melts spontaneously on the surface of the copper, without putting the flame
to it, then solder the joint. Touch the tip of the solder to the crack of the joint, playing it around as
far as convenient until you can see that the solder has flowed all the way around the joint. This is
done without the flame.
- Then solder the other outlets of the fitting.
- Immediately take a reasonably clean rag and wipe around the joint to smooth out excess solder
and remove excess flux. Let the joint cool.
- When repairing copper pipe that has already been carrying water, it's important to drain it out
thoroughly first or you'll never get the pipe hot enough to get a good solder seal. Open the
highest-level taps in the house for the water line, as well as the lowest ones, to drain out as much
water as possible. Then make your cuts in the pipe to prepare for the repair. Next, plug the pipe
to stop water drips after you've drained out as much water as possible. A quick and easy way to
do this is to take a slice of store-bought white ("balloon") bread, wad it up, and shove it back into
the pipe firmly. When the water is turned back on, the water will easily dissolve and flush out the
bread. Gelatin plug kits are also available at hardware and building supply stores.
- Each plumbing fixture and appliance in the house has a trap. It's part of the body of the toilet,
but for most fixtures and appliances, it's part of the plumbing beyond. The trap is a sump, or dip
in the plumbing, that always holds water so that it makes an air seal between the inside of the
house and the sewer system (or septic system). This prevents sewer gases from coming into the
house. Sewer gases can actually be very dangerous as well as obnoxiously smelly; they can
asphyxiate people or even explode. The traps also helps keep the heat in the house in the winter
and to keep vermin out all year-round. It's important that all traps have water in them at all times.
However, if there is a sink, floor drain, washing machine outlet, toilet, or other item that is not
being used, the water in the trap may dry up. It's a good idea to pour water through any unused
traps at least twice per year. It also may be a good idea to add a capfull or two (CAPfull, NOT
cupfull) of bleach to the trap for disinfection.
- There are actually four type of plumbing in the average house. The water supply plumbing is
only one of the four. The other three are: waste, drain, and vent. You will see some plumbing
fittings designated "DWV," which means "drain/waste/vent," and means that the fitting is
approved for all three uses. These three types of piping usually all connect together. The pipes
that carry away waste water from fixtures such as toilets and sinks are the waste pipes (the actual
waste from a toilet is called "soil"). Drain pipes are only those that directly serve to carry away
stormwater or water from floor drains. Vent pipes connect to waste pipes, and sometimes drain
pipes, to provide a source of air and a place for gases to go. Each waste pipe from each fixture in
the house is supposed to have an individual vent pipe attached beyond the trap. These vent pipes
attach together when they are at least six inches above the "flood rim level" of each fixtures, to
make sure that they never become waste pipes. The vent pipes provide a source of air flow so that
flowing waste water don't suck traps dry, and also provide a place for sewer gases to go so that
they don't push their way into the house through the traps. Vent pipes that pass through the roof
should always be at least three inches in diameter to prevent icing-up problems.
- In the past, DWV systems were made of cast-iron "soil pipe." However, the soil pipe does
eventually corrode away, and it's very heavy and hard to work with. Today, DWV plumbing
systems are usually made of PVC (polyvinyl chloride). Schedule 40 DWV is required for waste
systems. Lighter weights (Schedules 20 and 30) are strictly for vent and drain systems, not waste.
The heavy schedule 40 is very strong and rigid and does not clog or corrode. Also used sometimes
is ABS (aluminum borosilicate), but it is not as common or reliable.
- To properly glue together PVC, the ends of the pipes should be first cut square. Many people
find this difficult. Usually, a hacksaw is used. However, a circular saw or chop saw may also be
used, and many people find it much easier to properly cut the PVC with one of these tools. Then,
a cleaning solvent should be used that's made for the purpose. Both the surface of the inside of
the fittings and the corresponding surface of the outside of the pipe should be thoroughly cleaned
with the cleaner. This both cleans the surfaces so that the glue will hold better, but also softens the
plastic itself so that the glue will properly weld it together. Then, the glue should be applied to
completely coat both surfaces, and the pieces should be fitted together with a twisting motion until
completely seated.
- When installing a water heater, use heat-trapping nipples in the top. These are usually sold in
pairs, and feature internal ball valves that automatically open to allow water to flow, but close
when no water is flowing. These reduce heat loss from the water heater. Also used unions so that
the water heater may be easily connected to and disconnected from the system.
Glossary
- adaptor: a fitting that either provides a way to change the size of the pipe (reducing coupling),
or that provides a way to change the type of pipe
- appliance: in plumbing, a device that uses water and attaches to the plumbing and uses an
external source of power, such as a dishwasher, washing machine, or water heater. Also see
fixture.
- bend: see ell
- bibb: see hose bibb
- boiler drain: a stop valve similar to a hose bibb, but with a male thread (outside, or exposed,
thread)
- cap: a fitting with only one hole, that fits over the end of a pipe to close it off. Also see plug.
- cleanout: a fitting that attaches to a pipe that has a threaded plug (or cap) that can be removed
for cleaning purposes
- coupling: a fitting with two holes that permanently joins together two pipes.
- ell: also called elbow, a fitting with two openings and a bend between, for changing direction
in pipes. A right-angle ell is called a 90-ell, and a 45-degree ell is called a 45-ell. In DWV
plumbing, 90-ell is also called a quarter bend, and a 45-degree ell is similary called an eighth-bend.
There are also a 60-degree fitting called a sixth-bend and a 22.5-degree fitting called a sixteenth-
bend.
- fixture: any plumbing device that uses water for a specific purpose but has no powered parts,
such as a toilet, lavatory, tub, shower, or sink. Also see appliance
- flange: a fitting that features a flat part so that it can be fastened down with screws or nails
- flood rim level: the level at which a fixture, when filled with water, will overflow
- flux: a paste or thick liquid that is applied to metal before soldering, and which etches the
surface of the metal and helps the solder to flow and adhere to the metal
- frostproof valve: a hose bibb that features a long stem, so that the valve is inside the house
while the handle is outside the house, and so that any water remaining on the outside of the valve
automatically drains out whenever the valve is shut
- gate valve: a valve that opens and closes by moving a solid piece of metal that fits tightly
against machined surfaces
- hose bibb: a stop valve with a female thread (inside thread), and with a flange for mounting
with screws
- lavatory: a bathroom sink. Also sometimes used for the bathroom itself. It is NOT the toilet.
- leader: downspout from guttering
- nipple: a short piece of threaded pipe
- plug: a fitting that fits inside the end of a pipe to close it off
- soil: the waste from a toilet
- solder: a mixture of soft metals that melts at a low-enough temperature that it can be used to
provide a seal by adhering to harder metals
- stop: a type of valve that closes off by means of a rubber washer that provides a seal under
compression
- supply: a tube that carries a fresh water supply from a stop valve to a faucet or other plumbing
fixture
- tee: a plumbing fitting with three openings, so that three pipes may be fitted together
- trap: a compound bend in a pipe that provides a low point where water stays to provide an air
seal
- union: a fitting that joins together the ends of two pipes, which features two parts that fit
together with a threaded collar to clamp the ends together. The union enables the pipes to be
tightly joined but also makes it easy to take them apart when necessary.
- vent: a pipe for connecting waste/drain plumbing systems with the outside air
- waste: drainage from plumbing fixtures
- water closet: toilet
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