Introduction - Bradford White UCG100H3993N Service Manual

Introduction

The Bradford White Ultra Low NOx Atmospheric Vent Water Heater is designed to deliver a
remarkable amount of hot water at up to 82% thermal efficiency in a quiet running unit with a top
exhaust vent connection that allows for installation in existing locations. While this unit is vented
atmospherically there is no damper required to maintain heat loss during off cycle. Several
technologically advanced design features are incorporated that will require additional knowledge on
the part of the qualified service provider. The information in this manual will instruct service and
maintenance professionals on the function, proper diagnosis and repair of The Bradford White Ultra
Low NOx Atmospheric Vent Water Heater.
The Bradford White Ultra Low NOx Atmospheric Vent Water Heater uses an ultra low NOx premix
power burner located at the top of the water heater to direct a turbulent flame down into the water
backed combustion chamber. This turbulence causes a thorough mixing of gas and air for optimum
combustion. The combustion gases then travel through a two pass flue system keeping the gases
moving at a high velocity. The combination of high turbulence and velocity results in an optimum
transfer of heat from the flue gases into the water.
Burner operation is controlled using an electronic ignition module. The module monitors the status of
the electronic thermostat, blocked vent limit switch, flame sensor to control output voltage to blower
motor, spark rod and gas valve. The module contains programming which determines the sequence
of operation and timings for purge periods, trial for ignition, flame sensing and lockout. The module
will also provide diagnostic information to help in determining the cause of system lockouts.
The contents in this manual are detailed informational tools to assist in the proper diagnosis of the
Ultra Low NOx Atmospheric Vent Water Heater operational faults. Please read this service manual
completely and record as much information regarding the Ultra Low NOx Atmospheric Vent Water
Heater operation and installation specifics related to any concerns.
SAVE THIS MANUAL FOR FUTURE REFERENCE REV 11/15 238-51306-00B
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