A.O. Smith HYB-90N warranty Hard Water, Temperature-Pressure Relief Valve

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.

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 damage the tank.

SHUT-OFF

VALVE

COLD WATER	TEMPERED
INLET	POTABLE WATER

MIXING VALVE (OPTIONAL)

PIPE INSULATION (RECOMMENDED)

Rear View

FIGURE 16

NOTE: To protect against untimely corrosion of hot and cold water fittings, it is strongly recommended that di-electric unions or couplings be installed on this water heater when connected to copper pipe (see Figure 3 also).

Figures 3 and 16 show the typical attachment of the water piping to the water heater. The water heater is equipped with 3/4” NPT water connections.

HARD WATER

We highly recommend installing water filtering system or a water softener before the water heater system. If you are installing a water filtering system use a 5 micron filter to reduce particles that can potentially cause nuisance shutdown problems and prolong the maintenance of the water heater’s inlet filter. A water softener can affect the life of the anode installed in this water heater. Refer to “Anode Rod Inspection” section in this manual.

Clean the filter on the water inlet as frequently as required by the quality of your local water. Refer to “Cleaning The Inlet Water Filter” section of this manual. One additional filter is supplied with your water heater.

TEMPERATURE-PRESSURE RELIEF VALVE

This heater is provided with a properly certified combination temperature - pressure relief valve by the manufacturer.

The valve is certified 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 valve must meet the requirements of local codes, but not less than a combination temperature and pressure relief valve certified as indicated in the above paragraph.

The valve must be marked with a maximum set pressure not to exceed the marked hydrostatic working pressure of the water heater (150 psi = 1,035 kPa) and a discharge capacity not less than the water heater Btu/hr input rate as shown on the water heater’s rating plate.

For safe operation of the water heater, the relief valve must not be removed from its designated opening nor plugged.

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