Weil-McLain Series 2 Manual page 96

® S
ERIES
Troubleshooting
Check control fuses
ALWAYS check ECO control fuses before replacing ECO
control or any major components (blower, etc.). If one
of these fuses is blown, it can prevent ECO control or
other components from operating.
1. Turn OFF power to boiler at external line switch. Then remove
the jacket door.
2. Locate fuses using Figure 103.
3. Remove and inspect the two fuses (items 1 and 2, Figure 103).
4. If necessary, replace one or both of the fuses:
a. Low voltage circuit fuse is 3-amp fast-blow
(Littelfuse 0287003).
b. Line voltage circuit fuse is 12-amp fast-blow
(Littelfuse 0314012MXP).
Do not jumper either fuse or replace with any fuse except
as specified. Failure to comply could result in severe
personal injury, death or substantial property damage.
Checking temperature sensors
1. The boiler temperature sensors (flue, outdoor, return water and
supply water) are all resistance-type devices. Figure 102 shows
the correct value for the sensor at various temperatures. For dual
sensors, the temperature difference between the sensors must be
no more than 10°F.
2. Use the resistance values at 32°F, 60°F, 70°F and 212°F to measure
the sensor resistance at known temperatures (ice point, room
temperature and sea level boiling point). For ice point and boiling
point, insert the sensor in water at that temperature. Use an
ohmmeter to read resistance value.
3. To check whether the ECO control is correctly sensing temperature,
you can use a resistance decade box. Connect the decade box
temporarily in place of a sensor and read the corresponding
temperature on the ECO control display. The temperature should
be close to the value corresponding to the input resistance.
Figure 102 Sensor resistance values
Temp Temp
Sensor ohms
(°F) (°F)
Min Max
32 34265 37871 90
40 100
27834 30764
50 21630 23907 110
60 16944 18727 120
70 13372 14780 130
80 10629 11747 140
96
2
-
G
AS FIRED WATER BOILER
(continued)
Temp
Sensor ohms Sensor ohms
(°F)
Min Max Min
8504 9399 150 2517
160
6847 7568 2091
5545 6129 170 1744
4517 4992 180 1461
3698 4088 190 1229
3043 3364 200 1038
— Boiler Manual
Figure 103 Control fuses
Line Voltage
2
1
Low
Voltage
Max
2782
2311
1928
1615
1359
1147
Part number 550-142-190/1218