Instruction Manual

15
Control Module Fuses
Check control module fuses before replacing 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 front panel.
3. Remove control module cover.
4. Inspect fuses F1 and F3 (shown below).
5. Boiler is shipped with four spare fuses attached to
control module cover.
6. If necessary, replace open fuse (F1 is 115V, 5-amp
fast-blow; F3 is 24V, 4-amp slow-blow).
7. Install control module cover and jacket top front cover
after fuse inspection.
8. Restore power to boiler at external line switch and
verify boiler operation after completing boiler service.
Checking Temperature Sensors
1. Boiler temperature sensors (outdoor, return water, and
supply water) are all resistance-type devices.
2. Table 1 shows correct resistance value for sensor at
various temperatures.
3. Use resistance values at 32°F, 60°F, 70°F and 212°F to
measure sensor resistance at known temperatures (ice
point, room temperature and sea level boiling point).
For ice point and boiling point, insert sensor in water
at that temperature. Use ohm meter to read resistance
value.
4. To verify control module is correctly sensing
temperature, use a resistance decade box. Connect
decade box temporarily in place of sensor. Use control
module “Information” mode to read temperature.
9 - TROUBLESHOOTING
DANGER
Electric shock hazard! Disconnect power before
servicing. All service must be performed by a
trained, experienced service technician. Never
jumper (bypass) any device except for momentary
testing as outlined on the following pages of this
manual. Failure to follow these instructions WILL
result in death or serious injury
!
F1 and F3 Fuses
Temp
°F
Sensor Ohms
Temp
°F
Sensor Ohms
Min Max Min Max
32 34,265 37,871 130 3,698 4,088
40 27,834 30,764 140 3,043 3,364
50 21,630 23,907 150 2,517 2,782
60 16,944 18,727 160 2,091 2,311
70 13,372 14,780 170 1,744 1,928
80 10,629 11,747 180 1,461 1,615
90 8,504 9,399 190 1,229 1,359
100 6,847 7,568 200 1,038 1,147
110 5,545 6,129 210 880 972
120 4,517 4,992 212 851 941
Table 1 - Sensor Resistance Values at Various
Temperatures