User Guide

Part number 550-100-325/0718
87
AquaBalance
®
SERIES 2 WALL MOUNT GAS-FIRED WATER BOILER — Boiler Manual
34 Troubleshooting (continued)
Temp
(°F)
Sensor ohms
Temp
(°F)
Sensor ohms
Temp
(°F)
Sensor ohms
Min Max Min Max Min Max
32
31530 33480
100
5608 5954
170
1344 1428
40
25792 27388
110
4590 4874
180
1143 1213
50
19258 20450
120
3636 3860
190
945 1003
60
15218 16160
130
3011 3197
200
810 860
70
11577 12293
140
2417 2567
212
657 697
80
8891 9441
150
1954 2074
-
--
90
7185 7629
160
1644 1746
-
--
Check flame signal
1. Navigate to Diagnostics/Inputs on the control display (see
pages 58 to 62 for navigation instructions.
2. The flame signal value must be at least 25 on low fire. The
flame signal value must be at least 255 on high fire, reading
at times 10 equals microamps of flame signal. If the flame
signal drops below this level, the control will attempt to cor-
rect by increasing the blower speed to increase flame signal.
3. A low flame signal may indicate a fouled ignitor or damaged
ignitor cable insulation.
a. See “Inspect ignition electrode,” page 107 to remove
and inspect the ignitor.
b. If required, clean the ignitor and flame rod as in-
structed, see page 107.
c. If cleaning the ignitor does not improve, ground wiring
is in good condition, and ground continuity is satisfac-
tory, replace the ignitor.
4. If flame signal still remains low:
a. Inspect the vent and air piping.
b. Check combustion values.
c. Then inspect the heat exchanger, following the proce-
dures given in this manual for inspecting and clean-
ing of the heat exchanger cover plate and other boiler
components (starting on page 107).
d. Clean the heat exchanger as described in this manual if
necessary, see page 110.
Check control fuse
ALWAYS check circuit fuses before replacing
control or any major components (blower,
etc.). If a fuse is blown, it can prevent the con-
trol 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 111 and Figure 112.
3. Remove and inspect the fuses (Item a, Figure 111 or Item
b, Figure 112).
4. If necessary, replace the fuses:
a. Control circuit fuse is a 250 VAC 3.15-amp rated
fuse. (Littelfuse 326012P)
b. Thermostat-relay circuit fuse is a 250 Volt 630mA rated
fuse. (Littelfuse 071-852 Type 5 x 20mm).
Do not jumper fuses 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 113 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. (Supply
outlet 200 sensor).
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 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 control display. The temperature should
be close to the value corresponding to the input resistance.
Figure 111 Control circuit fuse location
Figure 112 Thermostat-relay circuit fuse location
Figure 113 Sensor resistances values
Installer/homeowner note,
in case of an “open circuit”
of the Thermostat-relay
fuse the boiler can run in
DHW mode but NOT in
Central Heating mode.
Fuse located on rear of circuit board
a
b