Upper Thermister, Lower Thermister | Bradford-White Corp D38T155

SERVICE PROCEDURE D24-I

Thermostat Circuit Testing

Thermister Resistance Testing

Upper Thermister:

1.Determine resistance value of upper thermister. Test across grey wires. (see photo 9).

2.Draw quart of water off T&P valve. Using a thermometer, determine water temperature.

3.Use table below to verify correct resistance per water temperature measured.

Lower Thermister:

1.Determine resistance value of lower thermister. Test across blue wires. (see photo 10).

2.Draw quart of water off Drain Valve. Using a thermometer, determine water temperature.

3.Use table below to verify correct resistance per water temperature measured.

Are readings N		Replace
correct?		thermister
	Y
	Y

Upper thermister location

(applicable models)

Lower thermister

access located inside

control box.

Check harness	N	Replace
continuity.	N	Replace
continuity.		harness	CAUTION
Continuity okay?		harness
Continuity okay?
Y			Be Careful When Making Resistance
			Measurements Not to Damage or
Replace			Deform Connectors or Connector Pins.
Replace
thermostat
board		Thermister Resistance at Various Temperatures
		Thermister Resistance at Various Temperatures

Example: If water temperature is 84°F, then the resistance through the sensor would be 8449 (see shaded area).

NOTE: Sensor resistance increases as the temperature falls.

In Degrees F

°F	0	1	2	3	4	5	6	7	8	9
40	26109	25400	24712	24045	23399	22771	22163	21573	21000	20445
50	19906	19383	18876	18383	17905	17440	16990	16553	16128	15715
60	15314	14925	14548	14180	13823	13477	13140	12812	12494	12185
70	11884	11592	11308	11032	10763	10502	10248	1000	9760	9526
80	9299	9078	8862	8653	8449	8250	8057	7869	7685	7507
90	7333	7165	7000	6839	6683	6531	6383	6238	6098	5961
100	5827	5697	5570	5446	5326	5208	5094	4982	4873	4767
110	4663	4562	4464	4368	4274	4183	4094	4006	3922	3839
120	3758	3679	3602	3527	3453	3382	3312	3244	3177	3112
130	3048	2986	2925	2866	2808	2752	2697	2643	2590	2538
140	2488	2439	2391	2344	2298	2253	2209	2166	2124	2083
150	2043	2004	1966	1928	1891	1856	1820	1786	1753	1720
160	1688	1656	1625	1595	1566	1537	1509	1481	1454	1427
170	1402	1376	1351	1327	1303	1280	1257	1235	1213	1191
180	1170	1150	1129	1110	1090	1071	1053	1035	1017	999
190	982	965	949	933	917	901	886	871	857	842
200	828	814	801	788	775	762	749	737	725	713

Page 7

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.