Troubleshooting, S1a inlet/outlet/system/tank, S1b outlet only – Lochinvar Copper-fin II/IIE 402 - 2072 User Manual

Page 35: Checking temperature sensors

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3

Troubleshooting

(continued)

35

Temperature

Resistance

Temperature

Resistance

-50

490,813

20

46,218

-40

336,606

30

34,558

-30

234,196

40

26,099

-20

165,180

50

19,900

-10

118,018

60

15,311

0

85,362

70

11,883

10

62,465

80

9,299

Checking temperature sensors

The appliance temperature sensors (inlet water, outlet water, system water, tank water, flue, and outdoor air) are all resistance
type devices. The following tables show the correct values for the sensors at various temperatures. Use an ohmmeter to read
the resistance of the sensor at a known temperature. If the resistance of the sensor does not closely match its corresponding
table, replace the sensor.

Table 3B Inlet/Outlet/System/Tank Sensor Resistance vs. Temperature

Table 3C Outdoor Air Sensor Resistance vs. Temperature

Copper-fin II/IIE Boiler and Water Heater

Service Manual

S1a Inlet/Outlet/System/Tank

(Wire Color - R and W)

S1b Outlet Only

(Wire Color - Bk and G)

Temperature Resistance Temperature Resistance Temperature Resistance Temperature

Resistance

50

19,553

158

2,004

50

40,030

158

3,478

68

12,690

176

1,464

68

25,030

176

2,492

86

8,406

194

1,084

86

16,090

194

1,816

104

5,715

212

816

104

10,610

212

1,344

122

3,958

122

7,166

140

2,786

140

4,943

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