Supply Gas Regulator; Space Heating And Potable Water System; Solar Installation - A.O. Smith 300 Series Instruction Manual

SUPPLY GAS REGULATOR

The maximum allowable gas supply pressure for this water heater
is 14 inches W.C. (3.5 kPa). Install a positive lock-up gas pressure
regulator in the gas supply line if inlet gas pressure can exceed 14
inches W.C. (3.5 kPa) at any time. Regulators must be sized/used
according to manufacturer's specifications.
If a positive lock-up regulator is required follow these instructions:
Positive lock-up gas pressure regulators must be rated at or
1.
above the input Btu/hr rating of the water heater they supply.
Supply gas regulators shall have inlet and outlet connections
2.
not less than the minimum supply gas line size for the water
heater they supply
Positive lock-up gas pressure regulator(s) should be installed no
3.
closer than 3 feet (1 meter) and no farther than 8 feet (2.4 meters)
from the water heater's inlet gas connection.
After installing the positive lock-up gas pressure regulator(s) an
4.
initial nominal supply pressure setting of 7.0" W.C.(1.74 kPa) for
Natural Gas and 11.0" W.C . (2.74 kPa) for Propane (LP) while
the water heater is operating is recommended and will generally
provide good water heater operation. Some additional adjustment
may be required later to maintain a steady gas supply pressure.
When installing multiple water heaters in the same gas supply
5.
system it is recommended that individual positive lock-up gas
pressure regulators be installed at each unit.
All gas piping must comply with local codes and ordinances or with
the current edition of the Natural Gas and Propane Installation Code (CSA
B149.1). Copper or brass tubing and fittings (except tin lined copper
tubing) shall not be used.
If the gas control valve is subjected to pressures exceeding 1/2 psi
(3.5 kPa), the damage to the gas control valve could result in a fire
or explosion from leaking gas.
If the main gas line Shut-off serving all gas water heaters is used,
also turn off the gas at each water heater. Leave all gas appliances
shut off until the water heater installation is complete.
A gas line of sufficient size must be run to the water heater. Consult
the current edition of the Natural Gas and Propane Installation Code (CSA
B149.1) and your gas supplier concerning pipe size.
There must be:
A readily accessible manual shut off valve in the gas supply line
•
serving the water heater, and
A sediment trap ahead of the gas control valve to help prevent
•
dirt and foreign materials from entering the gas control valve.
A removable connection of proper size between the manual shut
•
off valve and control valve to permit servicing of the unit.
Be sure to check all the gas piping for leaks before lighting the water
heater. Use a soapy water solution, not a match or open flame. Rinse
off soapy solution and wipe dry.

SPACE HEATING AND POTABLE WATER SYSTEM

Your water heater is equipped with inlet/outlet connections for use
in space heating applications. See Figure 13. If this water heater is to
be used to supply both space heating and potable (drinking) water,
the instructions listed below must be followed:
Be sure to follow the manual(s) shipped with the air handler or
•
other type heating system.
This water heater cannot be used in space heating applications
•
only.
This water heater is not to be used as a replacement for an
•
existing boiler installation.
Do not use with piping that has been treated with chromates,
•
boiler seal or other chemicals and do not add any chemicals to
the water heater piping
If the space heating system requires water temperatures in
•
excess of 120°F, a mixing valve must be installed per the
manufacturer's instructions in the potable hot water supply to
limit the risk of scald injury.
Pumps, valves, piping and fittings must be compatible with
•
potable water.
A properly installed flow control valve is required to prevent
•
thermosiphoning. Thermosiphoning is the result of a continuous
flow of water through the air handler circuit during the off cycle.
Weeping (blow off) of the temperature and pressure relief valve
(T & P relief valve) or higher than normal water temperatures
are the first signs of thermosiphoning.
The hot water line from the water heater should be vertical past
•
any mixing valve or supply line to the heating system to remove
air bubbles from the system Do not connect the water heater to
any system or components previously used with non-potable
water heating appliances when used to supply potable water.
To reduce the risk of unusually hot
water reaching the fixtures in the
house, install thermostatic mixing
valves at each point of use.
Figure 13. Typical Mixing Valve Installation

SOLAR INSTALLATION

If this water heater is used as a solar storage heater or as a backup
for the solar system, the water supply temperatures to the water
heater tank may be in excess of 120°F (48.9°C). A mixing valve must
be installed in the water supply line to limit the supply temperature
to 120°F (48.9°C).
19
Burn Hazard