7
Basic operation
The water heaters covered in this manual have a helical coil
shaped heat exchanger that is submerged in the storage tank.
The water heater’s main Burner is a radial design burner, it
is mounted on the top and fires downward through the heat
exchanger. This is a forced draft burner; hot burning gases are
forced through the heat exchanger under pressure and exit
through the exhaust/vent connection located at the bottom of the
water heater. See Figure 1 and Figure 2.
features and components
BLOWER
BURNER
ASSEMBLY
MAIN
BURNER
(radial design)
HEAT
EXCHANGER
INTAKE AIR
(combustion air)
CONNECTION
4 INCH PVC
HELICAL
COIL
VENT (exhaust)
OUTLET
figure 1
Blower/Burner assemBly detail
HOT SURFACE
IGNITER
COMBUSTION
BLOWER
FLAME
SENSOR
MAIN
BURNER
(radial design)
BLOWER
FLANGE
INTAKE AIR
(combustion air)
CONNECTION
4 INCH PVC
figure 2
hot surface igniter
The control system energizes the Hot Surface igniter with 120
VAC during the igniter warm up period. When the igniter is
energized it produces sufficient heat, >1800°F (>982°C), to ignite
the main burner.
note:
Care must be taken when handling the igniter to prevent
breakage.
During the igniter warm up period prior to ignition the control
system monitors the igniter current and must sense a minimum
of 2.0 AC amps for BTH 300 & 400 models and 2.7 AC amps for
BTH 500 models. See the Sequence Of Operation on page 54.
flame sensor
The control system also monitors the flame sensor to confirm
a flame is present at the main Burner. if a flame is not verified
during the ignition trial period (3-5 seconds) the control system
will immediately de-energize the 24 VAC Gas Valve. See the
Summary of Contents for 101 Series
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