INTRODUCTION
The new Bradford White UDS and UDH water heaters are designed to provide reliable performance with enhanced standard features. Design features include reliable standing pilot ignition system, enhanced diagnostics, simplified servicing, certified FVIR technology and Ultra Low NOx emissions.
The UDS and UDH water heaters use a combustion system where combustion air is drawn from the outside of the building. The gas control maintains water temperature and maintains gas flow. If a situation outside of normal operating parameters exists, the gas control diagnostic LED wll 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 gas valve can be removed and replaced without draining the water heater.
Please read the service manual completely before attempting service on this new series of direct vent water heaters.
How the Safety System Works
During normal operation, air for the combustion chamber is drawn into the water heater through the vent pipe from outside your building. The air travels into the closed combustion chamber. The air then mixes in a normal manner with supplied gas and is efficiently combusted, producing Ultra Low NOx emissions.
In the unlikely event trace amounts of flammable vapors are present in the area surrounding the water heater, the sealed combustion system prevents the flammable vapors from reaching the ignition source.
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