Service Manual

Page 4
Introduction
The new Bradford White TTW1, TTW2 & TW4 water heaters are designed to provide reliable
performance with enhanced standard features. New design features include reliable spark to
pilot ignition system, enhanced diagnostics, simplified servicing, significantly quiet operation,
additional vent lengths and Bradford White Defender Safety System
®
.
Spark to Pilot Ignition System - employing the spark to pilot ignition system promotes
reliable and consistent pilot and main burner ignitions to provide hot water on demand.
Integrated Immersion Thermostat/Gas Control Valve with LED -was developed for ease
of troubleshooting by providing simple diagnostic codes to pinpoint an installation or
component performance issue.
New Powerful Blower - will eliminate problems with difficult venting situations.
Quieter and Cooler Blower Operation - blower noise is significantly reduced for both
interior and exterior environments. Cooler operation increases blower life by reducing bearing
wear and noise.
Rugged Wiring Connections - receptacle type connections promote error free wiring.
Increased Vent Lengths - increased venting performance is achieved while maintaining
Energy Factor & FHSR performance.
The TTW1, TTW2 & TW4 water heaters use a combustion system were flue gases are
combined with dilution air to reduce the flue gas temperature in the blower. The diluted flue
gases are evacuated to the exterior through low temperature vent materials. The gas control
maintains water temperature, ignition sequence and regulates gas flow. A safety circuit
consisting of a pressure switch and blower temperature switch verifies proper conditions exist
for safe and reliable operation. If a situation outside of normal operating parameters exists, the
gas control diagnostic LED will flash a code to positively identify an operational issue.
This service manual is designed to facilitate problem diagnosis and enhance service efficiency.
To further promote quicker service times the new gas valve can be removed and replaced
without draining the water heater. A special tool is required and will be provided with each gas
valve kit shipped from our Service Parts department.
Please read the service manual completely before attempting service on this new series of
power vent models.
Page 4
How the Safety System Works
During normal operation, air for combustion is drawn into the water heater through the opening in the
jacket. This air travels down and around the combustion chamber and enters through holes in the very
bottom of the corrosion-resistant combustion chamber. The air then travels up through the oriented flame
ar
restor plate louv
ers, where the velocity of the air is increased and its direction altered. The air then mixes
in a nor
mal manner with supplied g
as and is ef
ficiently combusted, producing very low NOx emissions.
In the unlikely event trace amounts of flammable vapors are present in the air flowing into the combustion
chamber, the vapors are harmlessly ignited by the burner. If flammable vapors are in sufficient quantity to
prevent normal combustion, the flammable vapor sensor recognizes this and shuts down the pilot and
main burner. Should the flammable vapors continue to burn, the flame arrestor plate prevents the flames
from traveling backwards and igniting vapors outside of the combustion chamber.