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SlimFit
Series 3
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 49 (natural gas) or
(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 (2) Control fuses and the Ex-
pansion 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 550-100-168/0516
COMMERCIAL CONDENSING GAS
(continued)
1
2
1
—
-
FIRED WATER BOILER
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.
5. Reinstall jacket top panel and boiler jacket door after check-
ing the fuses.
6. Restore power to boiler at external line switch and verify boiler
operation after completing boiler service.
Checking temperature sensors
1. The boiler temperature sensors (flue, outdoor, boiler out,
boiler in, heat exchanger and system) are all resistance-type
devices.
2. Figure 83 shows the correct value for the sensor at various
temperatures.
3. Use the resistance values at 32°F, 60°F, 70°F and 212°F to
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.
4. To check whether the control module 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 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
Boiler Manual
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
97
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