Weil-McLain ECO 110, Manual

Page: 96 / 132

Troubleshooting
(continued)
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
Part number 550-142-190/1218
96
Temp
(°F)
Sensor ohms
Temp
(°F)
Sensor ohms
Temp
(°F)
Sensor ohms
Min Max Min Max Min Max
32 34265 37871 90 8504 9399 150 2517 2782
40 27834 30764 100 6847 7568 160 2091 2311
50 21630 23907 110 5545 6129 170 1744 1928
60 16944 18727 120 4517 4992 180 1461 1615
70 13372 14780 130 3698 4088 190 1229 1359
80 10629 11747 140 3043 3364 200 1038 1147
® S
ERIES
2
G
AS
-
FIRED WATER BOILER
—
Boiler Manual
Figure 103
Control fuses
1
2
Line Voltage
Low
Voltage