Warning, Temperature and pressure relief valve, Closed system/thermal expansion – State MHEW2-40R-035D User Manual

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Please note the following:
•

The system should be installed only with piping that is

suitable for potable (drinkable) water such as copper,

CPVC, or polybutylene. This water heater must not be

installed using iron piping or PVC water piping.

•

Use only pumps, valves, or fittings that are compatible

with potable water.

•

Use only full flow ball or gate valves. The use of valves

that may cause excessive restriction to water flow is

not recommended.

•

Use only 95/5 tin-antimony or other equivalent solder.

Any lead based solder must not be used.

•

Piping that has been treated with chromates, boiler

seal, or other chemicals must not be used.

•

Chemicals that may contaminate the potable water

supply must not be added to the piping system.

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

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

of water grows, 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.
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.
IMPORTANT: Do not plug or remove the temperature and

pressure relief valve.

Closed System/Thermal Expansion

For protection against excessive pressures and
temperatures, a temperature and pressure relief valve must
be installed in the opening marked “T & P RELIEF VALVE”
(See Figure 9).

CAUTION: To reduce the risk of excessive pressures and
temperatures in this water heater, install temperature and
pressure relief protective equipment required by local codes,
but no less than a combination temperature and pressure
relief valve certifi ed by a nationally recognized testing
laboratory that maintains periodic inspection of the production
of listed equipment or materials, as meeting the requirements
for Relief Valves and Automatic Shutoff Devices for Hot

Temperature and Pressure

Relief Valve

Figure 9
Temperature And Pressure
Relief Valve Installation

Optional Location
Some Models Only

Temperature And
Pressure Valve

Discharge Line
3/4 Inch Min.
Do Not Cap Or Plug

Drain Pan

Floor Drain

6” Maximum

Air Gap

Explosion Hazard

If the temperature and pressure relief valve
is dripping or leaking, have a qualified
person replace it.

Examples of a qualified person include:
licensed plumbers, authorized gas company
personnel, and authorized service
personnel.

Do not plug valve.

Do not remove valve.

Failure to follow these instructions can
result in death or explosion.

WARNING