7 of 8
Troubleshooting
STEP FIVE
As in any troubleshooting procedure, it is important to isolate a problem as much as possible before proceeding. The error messages
greatly simplify troubleshooting of the PC702-1. When the control displays an error message, identify the fault from the look-up table
on page 8 and follow standard testing procedures to confirm the problem. If you suspect a wiring fault, return to step three and carefully
check all external wiring and wiring connections.
Sensor and Internal Faults
• If an outdoor sensor fault occurs, the PC702-1 will assume a fixed outdoor temperature of 32
°
F (0
°
C) and will target the appropriate
supply water temperature. An error message is displayed.
• If a supply sensor fault occurs, the PC702-1 turns the boiler off and displays an error message.
• If an EEPROM fault occurs, the PC702-1 turns the boilers off until all the settings are checked.
Adjustment of Settings
• If the outdoor temperature is cold and the rooms are cold, increase the BOIL DSGN setting by 5
°
F (3
°
C) per day.
• If the outdoor temperature is near the WWSD temperature and the rooms are cold, increase the BOILStart setting.
• If the boiler is cycling too often, increase the Differential setting or set control to Ad (Auto Differential). If the second stage is coming
on too soon, increase the Interstage Delay setting.
Testing the Sensors
A good quality test meter capable of measuring up to 5,000 k
Ω
(1 k
Ω
= 1000
Ω
) is required
to measure the sensor resistance. In addition to this, the actual temperature must be
measured with either a good quality digital thermometer, or, if a thermometer is not
available, a second sensor can be placed alongside the one to be tested and the readings
compared.
First measure the temperature using the thermometer and then measure the resistance
of the sensor at the control. The wires from the sensor must not be connected to the
control while the test is performed. Using the chart below, estimate the temperature
measured by the sensor. The sensor and thermometer readings should be close. If the
test meter reads a very high resistance, there may be a broken wire, a poor wiring
connection or a defective sensor. If the resistance is very low, the wiring may be shorted,
there may be moisture in the sensor or the sensor may be defective. To test for a defective
sensor, measure the resistance directly at the sensor location.
Do not apply voltage to a sensor at any time as damage to the sensor may result.
Temperature
Resistance
Temperature
Resistance
Temperature
Resistance
Temperature
Resistance
°
F
°
C
Ω
°
F
°
C
Ω
°
F
°
C
Ω
°
F
°
C
Ω
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
-34
-29
-23
-18
-12
-7
-1
4
10
16
21
27
32
38
43
49
54
60
66
71
77
82
88
93
234,196
165,180
118,018
85,362
62,465
46,218
34,558
26,099
19,900
15,311
11,883
9,299
7,334
5,828
4,665
3,760
3,050
2,490
2,045
1,689
1,403
1,172
983
829
Ω
Ω
POWER UP
Start
Interstage
Delay
DHW
Demand
Boiler
Demand
Start
Interstage
Delay
DHW
Demand
Boiler
Demand
Start
Interstage
Delay
DHW
Demand
Boiler
Demand
Start
Interstage
Delay
DHW
Demand
Boiler
Demand
Start
Interstage
Delay
DHW
Demand
Boiler
Demand
Outdoor
Temperature
The OUTDR element
is turned on. The
outdoor temperature
is displayed
Boiler
Temperature
Press and release
the
Item
button. The
boiler supply
temperature is
displayed.
Boiler Target
Temperature
Press and release
the
Item
button. The
boiler target
temperature is
displayed.
VIEW MENU
On power up, the
control displays all
segments for 2
seconds and the
control version
number.
The control then
automatically goes
to operating mode,
and displays the
outdoor
temperature.
To view all control settings, the
Item
button
may be pressed and held while in the View
Menu. The control will then scroll through all
the adjustable items.
OUTDR
°
F
TARGET
DSGN DIFF
BOIL
OUTDR
WWSD
°
F
°
C
1 2
MAX
MIN
OUTDR
°
F
1 2
BOIL
°
F
1 2
TARGET
BOIL
°
F
1 2
VIEW
VIEW ADJUST
VIEW
VIEW
VIEW
