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BASIC OPERATION
The water heaters covered in this manual have a helical
coil shaped heat exchanger that is submerged in the stor-
age 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
INTAKE AIR
(combustion air)
CONNECTION
3 INCH PVC
BLOWER
BURNER
ASSEMBLY
MAIN
BURNER
(radial design)
HEAT
EXCHANGER
HELICAL
COIL
VENT (exhaust)
OUTLET
Figure 1. SUF Water Heater Components
FEATURES AND COMPONENTS
and
.
Figure 1
Figure 2
MODULATION
The water heaters covered by this manual are capable of
modulating their firing rate. The combustion blower is controlled
by the Central Control Board (CCB). The CCB monitors the water
temperature in the tank and regulates the firing rate to achieve
the target temperature set-point. The firing rate is dictated by the
hot water draw, proximity to the tank temperature set-point, and
various other temperature limitations.
BLOWER/BURNER ASSEMBLY DETAIL
COMBUSTION
BLOWER
ASSEMBLY
FLAME
SENSOR
Figure 2. SUF Blower/Burner Components
SPARK IGNITER
The control system energizes the spark ignition transformer with
120 VAC during the ignition cycle. The spark ignition transformer
then sends a high-voltage current to the spark igniter which in turn
ignites the main burner air/gas mixture.
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-volt gas valve. See the
(page 58).
Of Operation Flow Chart
7
INTAKE AIR
(combustion air)
CONNECTION
3 INCH PVC
BURNER
FLANGE
SPARK IGNITER
MAIN
BURNER
(radial design)
Sequence
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