Rheem Tankless Water Heater User Manual

16

Make sure the location of the appliance allows
for easy access and operation.

Wall studs should be utilized when mounting
the water heater to the wall. Alternately, a
suitable piece of wood may be placed inside
or outside of the wall to span the distance
between the wall studs. Fasten the water
heater mounting brackets to the wood.

In case of dry wall or concrete wall, use 
drywall anchors or lag bolts.

The water heater requires 120VAC/60Hz.
Have a receptacle with ground terminal near
the water heater. The length of the power
supply cord is 10 feet (3 m) (indoor water
heater only.)

Install a wood screw for the upper bracket
with a clearance of 1/8” (.32 cm) between the
wall and the screw head. Hang the center of
the upper bracket on the screw.

Using a wood screw and a washer, affix the
lower bracket to the wall (Left and Right).
Repeat to affix the top bracket.

The brackets can be adjusted to change the
distance between the back of the appliance
and the wall within the range of 3/8” (.95 cm)
to 1-1/2” (3.8 cm).

Loosen the adjustment screws of both the top
and the bottom brackets to adjust the distance
(See diagram below).

Bracket

Bracket

Adjustment Screws

Adjustment Screws

TOP

BOTTOM

Upper Bracket

Washer

Washer

Wood 
Screw

Wood 
Screw

Wood 
Screw

Lower Bracket

1/8" (.32 cm)

Clearance

Plumbing should be carried out by a qualified
plumber in accordance with local codes.

Use approved plumbing materials only.

The diameter of the pipe lines should be a
minimum of 3/4”(2 cm).

To conserve energy and to prevent freezing,
insulate both cold and hot water supply 
lines. DO NOT cover the drain or pressure
relief valve.

To ensure proper operation of the water
heater, the following water pressure guidelines
should be followed:

●

Operation of the water heater requires the
minimum water pressure of 14 psi (97 kPa)
and a minimum water flow rate of 0.66
gpm (2.5 lpm).

●

A water pressure of 40 psi (276 kPa) is
required to achieve maximum flow rate.

●

To maintain proper performance, ensure
sufficient water supply pressure. The

Required Water Pressure = Min. Operating
Water Pressure (14 psi [97 kPa]) + Pipe
Pressure Loss + Faucet and Shower
Pressure Loss + Safety Margin (more than
5 psi [34 kPa]).

●

To supply hot water to upper floors,
additional water pressure (0.44 psi/ft 
[10 kPa/m]) must be ensured. The
measurement should be calculated by the
distance between the water inlet of the
water heater (ground level) to the hot 
water faucet (upper floor level).

●

Well water systems should be set to ensure
a minimum system pressure of 40 psi (276
kPa). The pressure should remain stable
during the operation of the water heater.

●

When the water is supplied from a water
supply tank, the height of the tank and the
diameter of the pipes and their relation to
water pressure should be taken into
consideration. Gravity water pressure is
not recommended.

A thermal expansion tank will be required if
the water heater is installed in a closed loop
system to prevent damage to heater, related
piping and relief valve. Replacing the relief
valve will not correct the problem! The
expansion tank is designed with an air cushion
built in that compresses as the system pressure
increases, thereby relieving the over pressure

condition and eliminating the repeated
operation of the relief valve. Other methods of
controlling thermal expansion are also
available. Contact your installing contractor,
water supplier or plumbing inspector for
additional information regarding this subject.