Rheem Performance XG29T06MH32U1 Use and Care Manual download pdf (Page 10)

10

Installing the water heater

Thermal Expansion

Determine if a check valve exists in

the inlet water line. Check with your

local water utility company. It may

have been installed in the cold water

line as a separate back flow preventer,

or it may be part of a pressure reducing

valve, water meter or water softener. A

check valve located in the cold water

inlet line can cause what is referred to as

a “closed water system”. A cold water

inlet line with no check valve or back

flow prevention device is referred to as

an “open” water system.

As water is heated, it expands in volume

and creates an increase in the pressure

within the water system. This action is

referred to as “thermal expansion”.

In an “open” water system, expanding

water which exceeds the capacity of

the water heater flows back into the

city main where the pressure is easily

dissipated.

A “closed water system”, however,

prevents the expanding water from

flowing back into the main supply line,

and the result of “thermal expansion”

can create a rapid and dangerous

pressure increase in the water heater

and system piping. This rapid pressure

increase can quickly reach the safety

setting of the relief valve, causing it

to operate during each heating cycle.

Thermal expansion, and the resulting

rapid, and repeated expansion and

contraction of components in the water

heater and piping system can cause

premature failure of the relief valve, and

possibly the heater itself. Replacing the

relief valve will not correct the problem!

The suggested method of controlling

thermal expansion is to install an

expansion tank in the cold water line

between the water heater and the

check valve. 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.

Water Supply Connections

Refer to the illustration below for

suggested typical installation. The

installation of unions or flexible copper

connectors is recommended on the hot

and cold water connections so that the

water heater may be easily disconnected

for servicing if necessary. The HOT and

COLD water connections are clearly

marked and are 3/4 in. NPT on all

models. Install a shut-off valve in the

cold water line near the water heater.

IMPORTANT: DO NOT

apply heat to the HOT or

COLD water connections. If

sweat connections are used,

sweat tubing to adapter

before fitting adapter to the

cold water connections on

heater. Any heat applied

to the cold water supply

fittings will permanently

damage the dip tube.

NOTICE: The National

Fuel Gas Code (NFGC)

mandates a manual

gas shut-off valve: See

(NFGC) for complete

instructions. Local codes

or plumbing authority

requirements may vary

from the instructions

or diagrams provided

and take precedent over

these instructions.

ALTERNATE SEDIMENT

TRAP LOCATION

Hot Water

Outlet

To Fixtures

Roof Jack

Draft Hood

Flue Baffle

(Underneath)

Anode

Temperature

and Pressure

Relief Valve

Relief Valve

Discharge Line

to Suitable Drain

To Cold

Water

Supply

Jacket Door

Gas Control

(thermostat)

Union

Sediment

Trap

Manual

Gas

Shut-Off

To Gas

Supply

Drain

Valve

Typical Installation

Sediment

Trap

Drain Pan

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 27 28

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