A. O. Smith ET-5, PMET-2 Installation Manual

RESIDENTIAL & COMMERCIAL

HYDRONIC SPACE HEATING SYSTEM

EXPANSION TANK

INSTALLATION INSTRUCTIONS

SIZES 2 THROUGH 86 GALLON

SAFE INSTALLATION, USE AND SERVICE

Your safety and the safety of others is extremely important in the installation, use and servicing of this water heater.
Many safety-related messages and instructions have been provided in this manual and on your own water heater to warn you and others

of a potential injury hazard. Read and obey all safety messages and instructions throughout this manual. It is very important that the
meaning of each safety message is understood by you and others who install, use or service this water heater.

This is the safety alert symbol. It is used to alert you to
potential personal injury hazards. Obey all safety messages
that follow this symbol to avoid possible injury or death.

DANGER

W ARNING

CAUTION

CAUTION

All safety messages will generally tell you about the type of hazard, what can happen if you do not follow the safety message and
how to avoid the risk of injury.

DANGER indicates an imminently hazardous
situation which, if not avoided, will result in death
or injury.

WARNING indicates a potentially hazardous
situation which, if not avoided, could result in death
or injury.

CAUTION indicates a potentially hazardous
situation which, if not avoided, could result in minor
or moderate injury.

CAUTION used without the safety alert symbol
indicates a potentially hazardous situation which,
if not avoided, could result in property damage.

PRINTED 0210 205786-001

PURPOSE OF EXPANSION TANKS

When water is heated it expands. Provision must be made for this expansion in a closed hot water heating system. This
precharged diaphragm tank stores the expanded hot water and returns Air Free water to the system when the temperature
drops.

INSTALLATION

Install into a tee or tapping anywhere in the hot water heating system. A residential tank may be installed vertically or horizontally. The
tank may also be installed remotely and piped to system. A commercial tank must be installed vertically only.

For best installation, install the tank into the airout with the float vent as shown below. The airout device will provide both a
mounting tee and continuous automatic air removal from the system.

WARNING

This expansion tank is designed and intended for water storage at a maximum pressure of 100 psig and a maximum temperature
of 240°F. Any use other than water or at a sustained or instantaneous pressure in excess of 100 p sig is UNSAFE. A pressure relief
valve of adequate size must be incorporated in the system.

CAUTION

This expansion tank, as all expansion tanks, will eventually leak. Do not install without adequate drainage provisions where water
flow will cause damage. The manufacturer of this tank does not accept any liability or other responsibility for personal injury or
property damage resulting from improper use, installation or operation of this tank, or of the system of which it is a part.

RESIDENTIAL

Note: This tank was shipped with 12 psi air charge. NEVER LET AIR FROM TANK. Air charge

should always equal setting of reducing valve (12 pounds is standard.)

COMMERCIAL