Tee
A plumber should also be willing to peer
through the vent thimble with a flashlight and
mirror to check the chimney’s interior. All man-
Mission T-150
Tub-shoe gasket
trap adapter
ner of debris can accumulate in the bottom of a
Tub shoe (waste ell)
chimney—from soot to nests—and that debris
can block a chimney, hamper flue draft, and pos-
Chrome tailpiece
sibly force carbon monoxide into living areas.
Trap arm
The National Fire Protection Association sug-
P-trap
gests annual chimney and flue inspections and
whenever a new type of burning appliance is
vented into the flue, but inspection is really not a
If the tub drain is not accessible, plumbing codes require that joints be
plumber’s job. The Chimney Safety Institute of
glued together to prevent leaks. To join the tub tailpiece to the trap
America offers a state-by-state listing of chimney
assembly, use a Mission T-150 trap (11/2-in. tubular to 11/2-in. pipe).
P R O T I P
Don’t accept water heaters
whose boxes are bashed or torn.
water-heater elements are sensi-
tive. If the box has been handled
roughly or dropped, anode rods,
liners, or valves may have been
damaged.
a shower wall at rough-in. a pressure-balancing antiscald Finishing touches. To avoid marring the surface of a
valve (which mixes hot and cold water) is at the bottom of chrome shower arm, insert a sliding-jaw pliers handle into the assembly. The smaller valve above it controls water
the pipe and turn it into final position. When the
volume. Note the nail plates to protect the pipes.
bathroom is painted and all brightware is installed,
remove the protective plastic from the shower walls.
plumbing
351
Turn off the gas first—the stopcock
will be perpendicular to the gas line—
before removing an old gas-fired water
heater. use an adjustable wrench to
disconnect the gas coupling.
once the gas line is disconnected,
attach a hose to the drain at the
bottom of the water heater and drain
the tank.
a new gas-fired water heater in mid-installation. The red
lever-handled shutoff valve on the cold-water pipe is
required by code. after installing the TPR safety valve,
plumbers will reattach the vent pipe.
services with certified staff (check out its website
To vent
zzzzzz gas-Fired water heater
at www.csia.org).
Above all, installers should follow the water-
Hot-water outlet
heater manufacturer’s installation instructions
3/4-in. flexible copper or
closely to ensure a safe installation and to safe-
stainless-steel lines
guard the unit’s warranty should the water heater
fail to function properly.
Draft hood
draining the old water heater. The specifics of
Shutoff valve
disconnecting power or fuel to the old unit will
Cold-water
vary, depending on whether the water heater is
inlet
TPR valve
gas fired, fuel-oil fired, or electric. Once the
installer has disconnected the fuel or power
Brass nipples
source, the water should be shut off and the tank
drained. Typically, a hose will be attached to the
drain valve at the bottom of the tank. Using a
pair of pipe wrenches, unions (if any) on the hot-
Alternative
side outlet for
and cold-water pipes will be taken apart; if there
3/4-in.
TPR valve
are no unions, pipes will be cut 6 in. to 12 in.
discharge pipe
above the top of the heater—or a couple inches
discharges
above the cold-water shutoff valve—by means of
outside.
hacksaw or a wheeled cutter. Caution: Recipro-
cating saws aren’t used because the vibration
may weaken nearby pipe joints and cause leaks.
installing the new heater. If the unit is gas or
oil fired, the installer will disconnect the draft
hood and vent pipe and either wire them up out
Gas-supply
of the way or set them to one side. As noted earlier,
shutoff
the plumber should inspect the vent pipes. If the
hood or pipes are rusty or corroded, they should
Strap water heater
be replaced. When the old tank is empty, it can be
Flex connector
for gas
Thermostat
in earthquake regions.
walked out of the way. Be mindful of sharp edges
352 Chapter 12
on the newly cut pipes and the area around the
P R O T I P
old tank. Note: If codes require strapping the
unit, steel straps should be bolted to the wall
when replacing a water
behind before putting the new unit in place.
heater, put unions and lever-
Finally, if the pad beneath the old tank is in poor
handle ball valves on both the
condition or badly tilted, consider installing a
hot- and the cold-water pipes.
new prefab concrete pad. Then the new water
Code requires a shutoff valve only
heater can be walked into position.
on the cold-water pipe, but hav-
Making connections. What the installer does
ing them on both can make peri-
next depends on the size and condition of the
odic drainage and repairs easier.
pipes, what fittings are present, and, of course,
what type of water heater it is. There’s no single
right way to assemble pipes, but the photos on
the facing page show a typical installation in
progress for a gas-fired unit. There are 3⁄4-in.
Tankless water heaters are more
brass nipples screwed in the tank inlet holes,
expensive and more complicated to
flexible stainless-steel lines, sweat-to-threaded
install than tank-style heaters
because tankless models require
male adapters, valves, and (at the top) 3⁄4-in.
expertise in plumbing, electrical
rigid-copper trunk lines exiting to the upper
wiring, and gas fitting. The yellow
floors. Flexible stainless-steel or flexible copper
tubing entering at right is a CSST
supply lines are highly recommended for top-of-
gas line.
tank connections: Female nuts on both ends
make them easy to disconnect for future repairs.
installing a TPr valve. Many new water heaters
have preinstalled TPR valves. If there is none, the
plumber will install a TPR valve into the threaded
outlet atop the unit or in a side outlet a few inches Instal ing a Tankless
down from the top of the tank, lightly coat the
Water Heater
TPR valve’s threads with pipe compound, and
Tankless water heaters, also known as on-
then use
a pipe wrench to install the valve. Next,
demand, instant, or flash water heaters, don’t
the plumber will install a discharge pipe into the
have storage tanks for heated water. When some-
TPR valve’s threaded outlet. The pipe may be gal-
one opens a hot-water faucet and water begins to
vanized or rigid copper—but not plastic—and
flow through a tankless heater, a flow sensor
must slope downward. The discharge pipe should
P R O T I P
ignites the unit’s burner, and a heat exchanger
be terminated about 6 in. above the floor, at a
honeycombed with coiled water pipes heats up
safe location where hot water won’t scald anyone almost instantaneously. When the faucet or
In areas that lose power peri-
if it discharges.
shower valve shuts off and the water stops flow-
odically, a tank of hot water is a
Note: Threaded pipe fittings should be coated
ing, the sensor shuts off the burner.
nice thing to have on hand. If
with pipe compound or wrapped with Teflon tape
you live in an area where the
Tankless water heaters are generally more
to ensure a positive seal.
power goes out regularly, think
complicated and more expensive to install than a
twice about going tankless.
Final steps. The plumber will check the water
traditional tank heater but, on the whole, are less
heater for level, shim the base as needed, and
expensive to operate because there’s no energy
tighten the earthquake straps, if any. When all fit-
wasted keeping a tankful of water hot around
tings are connected, turn on the cold water to fill
the clock. In other words, tankless water heaters
the tank. Open the hot-water faucets to expel air.
consume energy only when hot water is needed.
When the tank is full, water will gush from the
About the size of a suitcase, tankless units are a
faucets. At that point, shut the faucets, and
great favorite when space is tight, too.
reconnect the fuel or power source as specified in
Their other great draw is that properly sized
the manufacturer’s instructions. Note: If the
tankless units never run out of hot water.
installer disconnected the bonding jumper wires
(Endless hot water is not free, of course: Linger
from the hot- and cold-supply pipes, those wires
too long in the shower and you’ll squander those
should be reclamped now to ensure proper
operating efficiencies.) As a rule of thumb, a
grounding for the house’s electrical system.
tankless unit with 140,000-Btu input will suffice
for a one-bath home with one or two users; a
190,000-Btu input should do for a two-bath home
with two to four people. (These figures assume a
unit with an energy factor of 0.82 or greater.) If
plumbing
353
your home has three baths and up, a pair of tank-
less water heaters located close to points of use
Tankless? gO WiTH a PrO may be a better call. Qualified installers can help
Installing tankless water heaters is best left to
calculate an optimal size for your home.
licensed professionals. as most units are gas
loCaTIng The unIT
fired, installations require gas, plumbing, and
electrical expertise. Because of safety issues—
If you locate a tankless water heater as close as
especially the correct installation of TPR
possible to the fixtures that use the most hot
valves—most local codes require permits for
water, you will lose less heat in transmission. In
replacing or installing water heaters. moreover,
new construction, that’s often easy to do. In reno-
almost all manufacturers make their warranties
vation, however, new tankless units are frequently
contingent on a professional installation.
installed near the site of the old tank-style heater
that’s being replaced—primarily because pipe
(Tankless water heaters average $1,000 unin-
hookups are already there.
stalled, so they are an investment worth protect-
Before deciding, however, consider what
ing.) Lastly, because tankless units are wall
connections your new water heater needs. Most
hung, clearances and venting details are particu-
tankless units require 3⁄4-in. water pipes, so if
larly exacting.
your old heater has only 1⁄2-in. water lines, that’s
one less reason to use that location. If your tank-
less heater is gas fired (as opposed to electric),
it will require a 3⁄4-in. gas line. Tankless units
have greater Btu input requirements than tank-
style water heaters. Electricity is rarely a problem
be-cause cables are easily routed and gas-fired
units need only 110v to run fans, sensors, and
the like.
Venting can be problematic, though, if you
hope to use an existing exhaust vent. Whereas
some tankless heaters have separate intake and
exhaust pipes, many others have a single concen-
tric direct-vent pipe—a pipe within a pipe—to
supply fresh air and exhaust combustion gas.
That pipe will have an optimal pitch to carry off
combustion condensation; see installation
instructions. Lastly, tankless models vary accord-
ing to whether they can be installed inside or out
and how close vents may be installed to operable
windows, eave vents, and so on.
ouT wITh The olD,
In wITh The new
If there’s an old tank-style water heater, turn off
electrical power and shut off the water supply to
the tank. Use a voltage tester to be sure the power
is off. Drain the tank, disconnect electrical con-
nections, and cut the hot- and cold-water pipes to
remove the old tank. If the old heater had a draft
hood and exhaust vent, remove them, too: Most
tankless models use concentric vent pipes.
Whether you are replacing an old water heat-
er or installing a new one from scratch, you need
five things: (1) a route for a vent pipe and an
opening to the exterior, if you are installing the
tankless unit indoors, (2) tie-ins to 3⁄4-in. water
pipes, (3) an electrical outlet for the unit’s power
Plumb and mount the water heater. Just visible to the right of the unit are
cord, (4) a gas line if the unit is gas fired, and
existing copper water pipes—a convenient place to tie the tankless unit into
house lines.
354 Chapter 12
Connecting to the underside of a tankless water heater is
Sweating copper leads to valve assemblies is also easier
easiest before it is mounted. Here, threaded stubs get an
beforehand. In the foreground, the (red) hot-water
application of pipe dope and Teflon tape; the stub at right assembly is being soldered. When soldering, heat the
(a hot-water outlet) has a union coupling attached.
fitting, not the pipe. V
alve assemblies (valve kits) save
time by combining fittings, including unions, shutoff
valves, and drains.
(5) a sturdy place to wall-mount the unit—
the water heater. Because PEX will melt when
whether 2x lumber or, say, a 5⁄8-in. plywood panel. exposed to open flame, it must not be directly
Review the installation instructions. If space
connected to gas- or oil-fired water heaters and
is tight, do as much work as you can before
must be kept away from some types of flue pipe.
mounting the tankless unit. For example, install
After connecting water pipes, flush the lines to
tees on existing supply pipes—so you can tie in
dislodge any debris that may have collected dur-
This takeoff atop a tankless unit gives
the tankless unit’s cold-water intake and hot-
ing the installation.
a good cross section of a concentric
water outtake pipes—and make a cutout for the
Gas connections performed by a licensed gas
direct–vent pipe. air for combustion
unit’s vent pipe, if needed. Using flexible corru-
fitter/installer are similar to water-pipe connec-
is pulled in through the outer pipe;
gated stainless-steel tubing (CSST) for gas pipe
tions. A 3⁄
exhaust gases are expelled through
4-in. union fitting joins the gas line to a
and flexible PEX for water-supply pipe will be
threaded stub on the underside of the heater.
the inner one.
easier to route in a renovation—if they are
Galvanized and black steel gas piping need a dirt
allowed by your local building codes.
leg (sediment trap), a short leg of vertical pipe
just upstream from unit connections, to act as a
sTurDy mounTIng,
cleanout. The gas line should also have a shutoff
solID ConneCTIons
valve. Check all gas-line connections for leaks by
Test-hang the tankless heater to make sure there
are adequate clearance distances and room to
make connections. Before mounting the unit,
pros often preassemble hot- and cold-water shut-
New gas
leg
off valve assemblies. Apply pipe dope and Teflon
tape to the threaded stubs on the underside of
the unit’s housing, and screw on a pair of union
couplings. If you are working with rigid copper,
this is also a good time to sweat (solder) pipe
leads to valve assemblies, as shown in the photo
at top right. Then attach a TPR valve to the out-
take (hot-water) valve assembly.
Renovation 4th Edition Page 82
