Sequence of Operation

1 Thermostat calls for heat.

The relay closes on the thermostat board, sending 24 volts from the “COM” terminal of the thermostat board to the flue damper.

2Flue damper begins to rotate open. Once damper is full open, 24 volts is allowed to continue through damper to the “TH” terminal of ignition module.

3LED on ignition module illuminates.

4Trial for ignition (90 second trials, 3 trials with 30 second pause between trials). Ignition module simultaneously sends:

1. 24 volts from “MV/PV” terminal, to “MV/PV” terminal of gas valve (common terminal).

2. 24 volts from “PV” terminal, through the ECO located in the lower thermister, to “PV” terminal of gas valve to establish

gas flow at pilot.

3.Low current high voltage from “spark” terminal, to generate spark at the pilot and ignite pilot gas flow.

4.Pilot flame proving signal (measured in micro-amps). from the “sense” terminal, to prove pilot flame.

5Once pilot flame is proven, sparking will stop.

6Once sparking stops, 24 volts is sent from “MV” terminal on module, to “MV” terminal on gas valve to establish main burner gas flow. Main burners ignite from the pilot flame.

The ignition module constantly monitors pilot flame. If pilot flame is lost, pilot and main burner are shut down. After a 30 second purge period, module will attempt to re-light pilot beginning at sequence 4 above.

7Main burner fires until the thermostat is satisfied. The relay on the thermostat board opens, interrupting 24 volts through the damper and ignition module. Pilot and main burner is turned off.

8	Flue damper rotates to the closed position.

LOCKOUT CONDITION

Ignition module will “lockout” if the pilot can not be lit after 3 ignition trials. The ignition module indicates a lockout condition by the continues flash of the LED located on the module.

Lockout reset is accomplished by interrupting 120 VAC to the unit for at least 5 seconds.

WIRING DIAGRAM

Page 4

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.