User Guide

ManualsBrandsAO Smith ManualsCommercial Water Heaters75 Gallon - 76,000 BTU Conservationist Power Direct Vent Commercial Gas Water Heater

CLOSED WATER SYSTEMS

Water supply systems may, because of code requirements

or such conditions as high line pressure, among others,

have installed devices such as pressure-reducing valves,

check valves, and back ﬂ ow preventers. Devices such

as these cause the water system to be a closed system.

THERMAL EXPANSION

As water is heated, it expands (thermal expansion). In a

closed system, the volume of water will increase. As the

volume of water increases, there will be a corresponding

increase in water pressure due to thermal expansion.

Thermal expansion can cause premature tank failure

(leakage). This type of failure is not covered under the

limited warranty. Thermal expansion can also cause

intermittent temperature-pressure relief valve operation:

water discharged from the valve due to excessive pressure

build up. The temperature-pressure relief valve is not

intended for the constant relief of thermal expansion. This

condition is not covered under the limited warranty.

METAL

DRAIN

PAN

FLOOR

DRAIN

HOT-WATER

OUTLET

COLD-

WATER

INLET

UNION UNION

3/4” SWEAT

FITTING

3/4” SWEAT

FITTING

TEMPERATURE-

PRESSURE

RELIEF VALVE

DISCHARGE PIPE

(DO NOT CAP

OR PLUG)

6 in.

MAX. AIR

GAP

DRAIN

VALVE

SHUT-OFF VALVE

SOME

COMPONENTS

NOT SHOWN

FOR CLARITY.

Figure 15

A properly-sized thermal expansion tank should be

installed on all closed systems to control the harmful

effects of thermal expansion. Contact a plumbing service

agency or your retail supplier regarding the installation of

a thermal expansion tank.

Note: To protect against untimely corrosion of hot and cold

water ﬁ ttings, it is recommended that di-electric unions or

couplings be installed on this water heater when connected

to copper pipe.

• Avoid water heater damage.

• Install thermal expansion tank if necessary.

• Do not apply heat to cold water inlet.

• Contact qualified installer or service agency.

Property Damage Hazard

CAUTION

Figure 15 shows typical attachment of water piping to the

water heater. The water heater is equipped with 3/4” NPT

water connections.

Note: If using copper tubing, solder tubing to an

adapter before attaching the adapter to the water heater

connections. Do not solder the water lines directly to the

water heater connections - it will harm the dip tube and

heat traps and damage the tank.

TEMPERATURE-PRESSURE RELIEF VALVE

• Temperature-pressure relief

valve must comply with ANSI

Z21.22-CSA4.4 and ASME

code.

• Properly sized temperature-

pressure relief valve must be

installed in opening provided.

• Do not plug, block, or cap the

discharge line.

• Failure to follow this warning

can result in excessive tank

pressure, serious injury or

death.

Explosion Hazard

WARNING

This water heater is provided with a properly rated/sized

and certiﬁ ed combination Temperature-Pressure Relief

Valve (T&P valve) by the manufacturer. The valve is

certiﬁ ed by a nationally recognized testing laboratory

that maintains periodic inspection of production of listed

equipment of materials as meeting the requirements for

Relief Valves for Hot Water Supply Systems, ANSI

Z21.22-CSA 4.4, and the code requirements of ASME.

If replaced, the new T&P valve must meet the requirements

of local codes, but not less than a combination temperature-

pressure relief valve rated/sized and certiﬁ ed as indicated

in the above paragraph. The new valve must be marked

with a maximum set pressure not to exceed the marked

hydrostatic working pressure of the water heater (150 psi)

and a discharge capacity not less than the water heater

Btu/hr input rate as shown on the water heater’s model

rating plate.