Check The Following; Checking Temperature Sensors - Weil-McLain SlimFit 2 Series Manual

™
SlimFit
COMMERCIAL CONDENSING GAS
Troubleshooting

Check the following:

1. Make sure heat demand is calling for heat and contacts (in-
cluding appropriate zone controls) are closed. Check for 24
VAC between thermostat wire nuts and ground.
2. Make sure all external limit controls are either installed (and
closed) or temporarily jumpered for testing.
3. Make sure that connectors to control module are securely
plugged in at module and originating control.
4. Gas pressures as specified on page 44 (natural gas) or page 44
(propane).
Always check Control module fuses
ALWAYS check control module fuses before re-
placing control module or any major components
(blower, etc.). If one of these fuses is blown, it can
prevent control module or other components
from operating.
1. Turn OFF power to boiler at external line switch.
2. Remove jacket door and jacket top panel. Rotate the swing-
away control panel forward to expose the Control module
and Expansion module.
3. Remove and inspect the two Control fuses and the Expan-
sion module fuse (located as shown below).
4. If necessary, replace the fuse:
a. Item 1 - Low voltage circuit fuse is a 3-amp fast-blow
(Littelfuse 0287003).
b. Item 2 - Line voltage circuit fuse is a 12-amp fast-blow
(Littelfuse 0314012 MXP or Bussman ABC-12-R).
Part number 550-100-162/0815
-
FIRED WATER BOILER
(continued)
5. Reinstall jacket top panel and boiler jacket door after check-
6. Restore power to boiler at external line switch and verify boiler

Checking temperature sensors

1. The boiler temperature sensors (flue, outdoor, boiler out,
2. Figure 81 shows the correct value for the sensor at various
3. Use the resistance values at 32°F, 60°F, 70°F and 212°F to
4. To check whether the control module is correctly sensing
1
2
1
—
Boiler Manual Series 2
Do not jumper fuse or replace with any fuse except
as specified. Failure to comply could result in severe
personal injury, death or substantial property dam-
age.
ing the fuses.
operation after completing boiler service.
boiler in, heat exchanger and system) are all resistance-type
devices.
temperatures.
measure the sensor resistance at known temperatures (freez-
ing point, room temperature and sea level boiling point). For
freezing point and boiling point, insert the sensor in water at
that temperature. Use an ohmmeter to read resistance value.
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 Control display. The
temperature should be close to the value corresponding to
the input resistance.
Sensor resistance values
Sensor resistance values
Sensor ohms
Temp
(°F)
Min Max
32 34265 37871
40
27834 30764
50 21630 23907
60 16944 18727
70 13372 14780
80 10629 11747
90 8504 9399
100 6847 7568
110 5545 6129
Sensor ohms
Temp
(°F)
Min Max
120 4517 4992
130
3698 4088
140 3043 3364
150 2517 2782
160 2091 2311
170 1744 1928
180 1461 1615
190 1229 1359
200 1038 1147
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