Bradford-White Corp D38T155 service manual Service Procedure D24-I, Thermostat Circuit Testing

Page 6

SERVICE PROCEDURE D24-I

Thermostat Circuit Testing

DANGER

120 volt exposure. To avoid personal injury, use caution while performing this procedure.

CAUTION

Be Careful When Making Voltage

Measurements or Jumping Terminals

Not to Damage or Deform Connectors or

Connector Pins.

This procedure assumes the flue damper is in working order. Be sure damper opens under its own power when the thermostat circuit is by-passed. Damper must be open or removed during this test. Do not force damper open using your hands or tools.

With power on to water heater,

3

Verify Primary and secondary voltage at

the transformer

(see photo 3)Rear terminals primary

(120 VAC)

THERMOSTAT CIRCUIT BY-PASS

 

Turn power “OFF” to water heater and

Forward terminals

secondary

locate thermostat board inside control box

(24 VAC)

of water heater. Disconnect YELLOW wires

 

from the thermostat board at location

 

“N.O.” & “COM”. Use a jumper to connect

 

these two wires together

 

(see photos 4 & 5).

DANGER

 

Do not leave thermostat jumper in

place for normal operation.

Turn power on to water heater.

N

Verify transformer voltage

Does LED on ignition module illuminate?

 

(see photo 3)

(see photo 6)

 

 

 

 

Y

 

 

 

 

 

Does pilot and main burner operate?

N

See pilot operation testing

 

(page 8)

 

 

 

 

Y

 

 

 

 

LED Location

Turn power “OFF”.

6

 

 

 

 

 

 

 

 

 

 

Remove jumper and re-connect wires to

 

 

 

 

thermostat board. Wires are identified for

 

 

 

 

 

proper connection to board.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Disconnect ORANGE potentiometer (temp

 

 

 

 

 

adjustment dial) wires from thermostat

 

 

 

 

 

board (see photo 7)

 

 

 

 

 

 

 

 

N

 

 

 

 

 

 

 

 

 

Check potentiometer for proper resistance values of:

 

Replace potentiometer

 

 

Greater then 4800 Ohms with dial at minimum setting.

 

 

 

 

Less than 50 Ohms with dial at maximum setting.

 

 

 

 

 

(see photo 8).

 

 

 

 

Check Thermisters

 

Are readings correct?

 

 

 

 

 

 

Y

 

 

(see page 7)

 

 

 

 

 

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5

7

8

6

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Contents Service Manual To be performed only by qualified service providersTable of Contents Tools Required for Service Sequence of Operation Lockout ConditionTroubleshooting To Avoid Personal InjuryService Procedure D24-I Thermostat Circuit TestingDo not leave thermostat jumper Place for normal operation Upper Thermister Lower ThermisterService Procedure D24-II Pilot Operation TestingIllustration ConditionService Procedure D24-III Main Burner Operation TestingProvide proper Main Burner Removal Service Procedure D24-IVMain Burner & Pilot Removal and Inspection Main Burner InspectionPilot Burner Removal Pilot Burner InspectionService Procedure D24-V Flue Baffle Removal, InspectionService Procedure D24-VI Generic Parts List 1/8 Reducer Bushing Temperature Control Knob ECO BTU/HCO2 GFIParts@bradfordwhite.com Techserv@bradfordwhite.com

Commerical 24 Volt Flue Damper series Water Heater, D38T155 specifications

Bradford-White Corporation is recognized for producing high-quality water heating solutions, and one of the standout products in their lineup is the D38T155 Commercial 24 Volt Flue Damper Series Water Heater. This water heater exemplifies the company’s commitment to efficiency, reliability, and advanced technology tailored to meet the demands of commercial establishments.

The D38T155 model features a robust design, engineered to provide consistent hot water delivery for a range of commercial applications. With a 38-gallon capacity, it is ideal for small to medium-sized businesses, including restaurants, hotels, and other facilities that require dependable access to hot water.

One of the key features of the D38T155 is its 24-volt flue damper system, which enhances energy efficiency. This technology prevents heat loss by closing the damper when the water heater is not in operation. As a result, the unit minimizes energy waste, contributes to lower utility bills, and simplifies compliance with stringent energy regulations. The flue damper's precision operation ensures that only the required amount of energy is utilized, optimizing performance.

The water heater is also equipped with a direct vent design. This allows for the safe venting of combustion gases, making it suitable for indoor installations while ensuring the surrounding environment remains safe and free of harmful emissions. The advanced insulation technology utilized within the tank further preserves heat, reducing the frequency of heating cycles and extending the lifecycle of the appliance.

In terms of maintenance, the D38T155 is designed with accessibility in mind. Its components are placed for easy access, allowing maintenance personnel to perform inspections and repairs with minimal disruption. This user-friendly design ensures that downtime is kept to a minimum, effectively supporting the operational needs of commercial facilities.

The Bradford-White D38T155 also showcases durability through its high-quality materials and comprehensive manufacturing process. Built with a glass-lined tank, it provides excellent corrosion resistance, prolonging the life of the water heater.

In summary, the Bradford-White D38T155 Commercial 24 Volt Flue Damper Series Water Heater combines advanced technology, energy efficiency, and reliable performance. With its user-centric design and durable construction, it stands as an optimal solution for businesses looking to meet their hot water needs effectively and economically.
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