Safety Lockouts; High Limit Controls (Energy Cut Off); Thermostat/Water Temperature; Blower High Limit Switch - A.O. Smith BPD-80 Series Installation And Operating Manual

This water heater has several lockout features designed
to prevent the heater from operating in unsafe conditions.

HIGH LIMIT CONTROLS (ENERGY CUT OFF)

Thermostat/Water Temperature

This feature is a part of the gas control valve/thermostat
(see Figure 1, item 12) and limits the maximum water
temperature. In the event of the water overheating, this
safety feature shuts off the fuel supply to the burner.

Blower High Limit Switch

This device is located on the blower (see Figure 4, item
47) and limits the maximum temperature of the blower.
If the blower temperature rises above the temperature
setting, the switch opens causing the heater to shut down.

LOCATING THE NEW WATER HEATER

FACTS TO CONSIDER ABOUT THE LOCATION

Carefully choose an indoor location for the new water
heater because the placement is a very important
consideration for the safety of the occupants in the building
and for the most economical use of the appliance. This
water heater is not for use in manufactured (mobile) homes
or outdoor installation.
Whether replacing an old water heater or putting the water
heater in a new location, the following critical points must
be observed:
1. Select a location indoors as close as practical to
the vent termination or location to which the water
heater vent piping is going to be connected, and as
centralized with the water piping system as possible.
2. Selected location must provide adequate clearances
for servicing and proper operation of the water heater.
3. Avoid locations that could cause the water heater to
freeze from outside air.
4. Selected location must provide access to a properly
grounded electrical branch circuit. A dedicated circuit
is preferred. Do not use a GFI outlet.
5. Avoid locations that expose the water heater to direct
sunlight.
6. Keep combustibles such as boxes, magazines,
clothes, etc., away from the water heater area.
Important: Do not use an extension cord to connect the
water heater to an electrical outlet.
CAUTION
Property Damage Hazard
• All water heaters eventually leak.
• Do not install without adequate drainage.
Installation of the water heater must be accomplished in
such a manner that if the tank or any connections should
14

SAFETY LOCKOUTS

The switch will auto reset once the temperature drops
sufficiently.

BLOWER AIR PRESSURE SWITCHES

The blower/heater is equipped with two air pressure
switches located in the junction box (see Figure 4, item
48 and item 51). These devices are connected in series
and monitor the air pressure produced by the blower. In
the event that the exhaust venting becomes blocked or
sufficiently restricted, the normally open (NO) air pressure
switch will shut down the heater. In the event that the
intake pipe becomes sufficiently blocked or restricted, the
normally closed (NC) air pressure switch will shut down
the heater.
leak, the flow of water will not cause damage to the
structure. For this reason it is not advisable to install the
water heater in an attic or upper floor. In all cases, a metal
drain pan should be installed under the water heater. Metal
drain pans are available at your local hardware store. Such
a metal drain pan must have a clearance of at least 1 in.
greater than any point on the water heater's outer jacket
and must be piped to an adequate drain. The pan must
have a maximum depth of 1.75 in. .
Water heater life depends upon water quality, water
pressure and the environment in which the water heater
is installed. Water heaters are sometimes installed in
locations where leakage may result in property damage,
even with the use of a metal drain pan piped to a drain.
However, unanticipated damage can be reduced or
prevented by a leak detector or water shut-off device used
in conjunction with a piped metal drain pan. These devices
are available from some plumbing supply wholesalers and
retailers, and detect and react to leakage in various ways:
•
•
•
•
Sensors mounted in the metal drain pan that trigger an
alarm or turn off the incoming water to the water heater
when leakage is detected.
Sensors mounted in the metal drain pan that turn off
the water supply to the entire building when water is
detected in the metal drain pan.
Water supply shut-off devices that activate based on
the water pressure differential between the cold-water
and hot-water pipes connected to the water heater.
Devices that will turn off the gas supply to a gas water
heater while at the same time shutting off its water
supply.
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