Installation Guide
 8 • Residen al Electric Water Heater Use and Care Guide
INSTALLATION
BACKGROUND: Water expands when 
heated, and the increased volume 
of water must have a place to go, or 
thermal expansion will cause large 
increases in water pressure (despite 
the use of a Pressure Reducing Valve 
on the home’s main water supply 
line). The Safe Drinking Water Act of 
1974 requires the use of backfl ow 
preventers and check valves to restrict 
water from your home reentering 
the public water system. Backfl ow 
preventers are o en installed in water 
meters and may not be readily visible. 
As a result, most all plumbing systems 
today are now “closed,” and almost all 
homes now need a Thermal Expan-
sion Tank. 
A Thermal Expansion Tank is a prac -
cal and inexpensive way to help avoid 
damage to the water heater, washing 
machine, dishwasher, ice maker and 
even toilet valves. If your toilet oc-
casionally runs for no apparent reason 
(usually briefl y at night), that may be 
due to thermal expansion increasing 
the water pressure temporarily. 
Water pipe and tank 
leaks 
Leaks from plumbing pipes or from 
the water heater itself can damage 
property and could cause a fi re risk. 
•  Install an automa c leak detec-
 on and shutoff  device (available at 
Lowe’s® ). These devices can detect 
water leaks and can shut off  the water 
heater’s water supply if a leak occurs. 
• Install a suitable drain pan (available 
at Lowe’s® ) under the water heater 
(fi gure 6) to catch condensa on or 
leaks in the piping connec ons or 
tank. Most codes require and we 
recommend installing the water 
heater in a drain pan that is piped 
to an adequate drain. The drain pan 
must be at least two inches wider 
than the diameter of the water 
heater. Install the drain pan so the 
water level would be limited to a 
maximum depth of 1-3/4”.
✓
Water tempera-
ture regula on
Install Thermosta c Mixing Valves (fi g-
ure 7) to regulate the temperature of 
the water supplied to each point-of-
use (for example, kitchen sink, bath-
room sink, bath, shower). Consult the 
valve manufacturer’s instruc ons or a 
qualifi ed person.
WARNING! Even if the water heater 
thermostat is set to a rela vely low 
temperature, hot water can scald. 
Install Thermosta c Mixing Valves at 
each point-of-use to reduce the risk of 
scalding (see page 4).
BACKGROUND: A Thermosta c Mix-
ing Valve, installed at each point-
of-use, mixes hot water from the 
water heater with cold water to more 
precisely regulate the temperature of 
hot water supplied to fi xtures. If you 
aren’t sure if your plumbing system 
is equipped with properly installed 
and adjusted Thermosta c Mixing 
Valves at each point where hot water 
is used, contact a qualifi ed person for 
more informa on.  ■
Figure 6 - A suitable drain pan piped to an 
adequate drain can help protect fl ooring from 
leaks and drips.
Figure 7 - Thermosta c Mixing Valves installed 
at each point-of-use can help prevent scalding.
INSTALLATION










