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Label all wires prior to disconnection when ser-
vicing controls. Wiring errors can cause improp-
er and dangerous operation. Always disconnect
power to boiler before servicing. Failure to com-
ply could result in severe personal injury, death
or substantial property damage. Never jumper
(bypass) any device except for momentary test-
ing as outlined on the following pages of this
manual. Severe personal injury, death or sub-
stantial property damage can result.
CONTROL MODULE FUSES
IMPORTANT: always check control module fus-
es before replacing control module or any major
components (blower, etc.) If one of these fuses is
blown, it can prevent control module or other com-
ponents from operating.
Turn OFF power to boiler at external line switch.
1.
Remove jacket front panel.
2.
Remove control module cover.
3.
Inspect fuses F1 and F3 (shown below).
4.
The boiler is shipped with four spare fuses attached to
5.
the control module cover.
If necessary, replace open fuse (F1 is 115V, 5-amp fast-
6.
blow; F3 is 24V, 4-amp slow-blow).
VIII - TROUBLESHOOTING
WARNING
F1 and F3 Fuses
Do not jumper fuse or replace with any fuse ex-
cept as specified. Failure to comply could result
in severe personal injury, death or substantial
property damage.
Install control module cover and jacket top front cover
7.
after fuse inspection.
Restore power to boiler at external line switch and verify
8.
boiler operation after completing boiler service.
CHECKING TEMPERATURE SENSORS
The boiler temperature sensors (outdoor, return water, and
1.
supply water) are all resistance-type devices.
The table below shows the correct resistance value for
2.
the sensor at various temperatures.
Sensor Ohms
Temp
°F
Min
34,265
32
37,871
40
27,834
30,764
50
21,630
23,907
60
16,944
18,727
70
13,372
14,780
80
10,629
11,747
8,504
90
100
6,847
5,545
110
4,517
120
Use the resistance values at 32°F, 60°F, 70°F and 212°F
3.
to measure the sensor resistance at known tempera-
tures (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 ohm meter to read
resistance value.
To check whether the control module is correctly sens-
4.
ing temperature, you can use a resistance decade box.
Connect the decade box temporarily in place of a sensor
and use the control module "Information" mode to read
the temperature.
15
WARNING
!
Sensor Ohms
Temp
°F
Max
Min
130
3,698
140
3,043
2,517
150
160
2,091
170
1,744
180
1,461
9,399
190
1,229
7,568
200
1,038
6,129
210
880
851
4,992
212
Max
4,088
3,364
2,782
2,311
1,928
1,615
1,359
1,147
972
941
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