Kitchen & Bath
Adding a Second Water Heater
One of the first things done by the average homeowner who is
running out of hot water is to turn up the thermostat on the
storage tank. This actually makes some sense because less hot
water is required to achieve the same mixed temperature ratio.
Raising the storage temperature from 120°F to 140°F
will increase energy costs for a standard water heater just $12
per year on average. However, if the problem is really one of
insufficient volume, the only practical solution is to install
a bigger water heater.
Adding a new bedroom, or a jetted tub, or a multihead "spa"
shower are all good reasons to increase a home's existing
hot-water supply. One solution is to install a separate,
dedicated water heater to handle the new outlet. But depending
on the extent of the re-routed distribution lines, installation
of a separate stand-alone water heater can cost at least $900.
Swapping out the too-small heater for a larger unit is another
alternative, but the drawback is that the cost of the tank and
its installation can easily exceed $1,500. Provided that the
existing water heater is relatively new and functions properly,
we often recommend adding a second heater and coupling the two
to double the supply capacity. This solution averages $700, a
substantial savings over the cost of a stand-alone
Once it's determined that adding a second tank makes sense,
there are two basic piping methods that work well:
reverse-return and series. Each offers independent operation if
one water heater fails or needs servicing. Other incorrect
piping methods commonly but erroneously used to add a tank not
only perform poorly but may also cause stagnation and ensuing
water-quality problems (see Figure 1).
Figure 1. This common
but incorrect method of adding a second water heater results in
unbalanced flow and stagnation in tank 2.
Reverse-return. Reverse-return piping ensures equal draw from
two tanks of equal size and capacity (Figure 2). Balanced flow
is assured by virtue of the fact that the incoming water's
shortest path is the first tank, while the hot water's shortest
path is from the second tank, which results in both tanks
seeing an equal flow.
Figure 2. Reverse-return
piping ensures balanced flow in two tanks of the same
Series piping is a must if the tanks aren't the same size
(Figure 3). In most cases, the new tank will be the larger of
the two because a 50-gallon tank costs a bit less than 40- and
30-gallon models. However, series piping can have a couple of
drawbacks. First, there's a loss of pressure during full flow
because of the longer pathway, since all of the hot water must
pass through both tanks and their related piping. Second, the
first tank in line will always handle the lion's share of the
heating, resulting in earlier burnout than the downstream
Figure 3. Series piping
is called for when the new tank is a different size (usually
bigger) than the existing tank.
Water heater life expectancy averages 10 to 15 years. While
standard efficiencies hover around 80%, a few gas-fired models
offer up to 99% efficiency. The built-in redundancy of a second
tank offers the added luxury of never being without hot water,
even if one tank fails. And as energy costs rise, the
relatively higher price of an ultra-high-efficiency water
heater can represent an excellent return on investment.
But remember, a fossil-fuel water heater requires adequate
flue-pipe sizing to effectively vent the carbon monoxide
produced. If both the new and existing water heaters must share
a flue, the flue size must be increased at the junction by at
least one pipe diameter. (Refer to manufacturer's venting
requirements and local codes for full compliance.) Generally
speaking, the chimney cross-sectional area should be a minimum
of 20% larger than the combined cross-sectional area of all
appliance flue outlets being served. In an older unlined
masonry chimney, a flexible insulated or uninsulated
stainless-steel liner (for oil- or gas-fired appliances) or
aluminum liner (gas-fired appliances only) should be installed.
Flue piping must pitch up from the appliance to the chimney at
1/4 inch per foot and every joint should be securely fastened
with a minimum of three stainless-steel self-tapping
Relief Valve Safety
A relief valve that drips whenever the burner runs indicates
that the system is subjected to higher-than-normal pressures.
Never plug a dripping relief valve. Water under pressure can be
superheated well above the boiling point of 212°F. A
powerful explosion can result as that superheated water turns
to steam and expands some 1,700 times in volume. The T&P
(temperature and pressure) relief valve on each tank should be
piped full size (typically 3/4 inch) to within 6 inches of the
floor and the piping should not be plastic. Plastic piping is
not suitable for use with 210°F water because a sudden
discharge of 210°F water can cause it to separate or be
dislodged, creating a scalding hazard for anyone nearby.
T&P valves will discharge under two conditions: if tank
pressure reaches 150 psi, or if water temperature reaches
Thermal expansion tanks must be taken into consideration
whenever you're installing a hot-water storage tank. Normal
water service includes a backflow prevention device or a
pressure-reducing valve, which effectively traps water upon
entry in the home's piping system. But as water is heated, its
volume increases. A 40-gallon water heater supplied by incoming
38°F water can produce a gallon of thermal expansion, so
an adequately sized thermal expansion tank is essential to
protect the home's plumbing from potential damage.
Twinned heaters can be served by a common expansion tank large
enough to handle their combined volumes, or each heater can
have its own properly sized expansion tank. These must be rated
for potable water and a minimum pressure of 150 psi. Note that
standard heating system expansion tanks are rated for a maximum
of only 30 psi. Be aware also that thermal expansion tank
manufacturers may base their sizing requirements on warmer
incoming water temperatures and lower finished water
temperatures than may be the case, either of which can lead to
undersized thermal expansion tanks, a stressed heater, and a
dripping relief valve.
A good rule of thumb for sizing thermal expansion tanks is to
apply a 1-to-4 ratio in order to minimize pressure spikes. So,
if a 40-gallon water heater produces a gallon of thermal
expansion, the tank volume should be at least 4 gallons. The
majority of potable water thermal expansion tanks are available
in a 4.5-gallon volume tank with a factory air-charge of 40
psi. Following installation, that air pressure should be
increased to within a few pounds of your incoming municipal or
private cold-water pressure.
Dave Yates owns and
operates F.W. Behler, a heating and plumbing contracting
company in York, Pa.
Hard as Rock.
sink line provides a "natural" accompaniment to a stone or
solid-surface countertop. Moen claims its MoenStone Granite
sinks match the natural stone's hard-wearing characteristics
with scratch-, chip-, and stain-resistant performance. The
single- and double-basin sinks may be drop-in or
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white, ivory, black, blue, and metallic. Prices range from $336
to $624, depending on style and color.
Moen, 800/289-6636; www.moen.com.
stand-alone stainless-steel module plays into the
mixed-materials countertop trend, eliminates several
installation steps, and looks great in a wide variety of style
settings. The AquaCentre 1050 features a single bowl and
integral drainboard, two removable tilt trays, and two nicely
detailed pull-out storage compartments with integrated sorting
baskets. Decorative panels are not included but may be
installed to match the surrounding cabinetry. High-end alert:
The unit retails for $7,000.
Here's a great idea that's really
practical with solid-surfacing materials. Swanstone Classics
combines its US-2021 large-bowl and US-1711 small-bowl sinks to
make a custom double-basin sink. Add other bowls, and the
design prospects are virtually unlimited. The bowls shown
retail for about $193 to $574, depending on size and
Swan Corporation, 800/325-7008,
So stated the
banner in a store window display in an old cartoon I read as a
kid. A character reading the banner asked, "Who don't know
that?" Anyway, whether used as an anchor or a kitchen basin,
the Forrester Cast Iron Kitchen Sink features "super-smooth ion
barrier Sana-Gloss glazing," said to be harder than porcelain
enamel and to reduce cleaning maintenance. The sink is
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optional rack insert ($85) and cutting board ($80). The sink
retails for $420 in white and $486 in colors.
Toto USA, 888/295-8134,
texture combines with photographically rendered wood grain to
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but are around $2 to $5 per square foot, plus cushion pad and
Witex Flooring, 800/948-3987,
Formed Like Stone.
three-dimensional surface texture and naturalistic coloring,
NatureForm high-pressure laminate tile creates a convincing and
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tile carries a 25-year limited warranty against water damage
under normal residential use, even in the bathroom. True to
laminate heritage, the tiles snap together without glue.
Material prices run approximately $5.30 per square foot.
Mannington Laminate, 800/356-6787,
11/16- and 6 11/16-inch plank widths makes it possible to blur
the giveaway modular look of typical laminate flooring. The
TimberView line further challenges eye and hand with V-groove
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edges promise simple installation without adhesives or special
tools. The 5/16-inch-thick planks are 50 5/8 inches long,
shipped in 8-piece, 13.29-square-foot cartons. The flooring
sells for about $3.50 to $4 per square foot.
and demanding installation requirements are two reasons clients
considering a conventional ceramic tile floor may be barking up
the wrong tree. Tap-N-Lock stone-look laminate tiles have
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subfloor, eliminating potential expansion cracks. The "premiere
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Wilsonart Flooring, 800/710-8846,