Setting Frost Protection; Troubleshooting; Error Codes Are Shown On The Display - Bosch SSB255 Installation And Service Manual

40 | Troubleshooting

Verify that the value of CO2 is stable and is within the range indicated in
the following table (be careful to make small changes and confirm that the
value is stable before making additional adjustment).
Select "Low Power" using "UP/Down" button and press "OK":
System Test
Test State
Fan Speed
Ionisation
The fan will run at the minimum speed.
To adjust the CO2 value at the minimum power turn the screw "B" shown
in Fig. 68 and in Fig. 70.
Verify that the value of CO2 is stable and is within the range indicated in
the following table (be careful to make small changes and confirm that the
value is stable before making additional adjustment).
Select "OFF" using "UP/Down" button and press "OK":
System Test
Test State
Fan Speed
Ionisation
The "Test State" switches to OFF and the boiler return to the "stand by"
mode.
Gas Type Max . power CO2%
Natural gas
LP gas 10.3-10.7
Tab. 16 CO2 value for gas valve calibration
Tab. 17 indicates the approximate number of turns required to start the
boiler when when LPG conversion kit has been installed. [refer to section
4.6.2 for NG to LPG conversion instructions].
The number of turns has been counted from when the maximum and
minimum adjustment has been wound fully closed.
This procedure is not applicable to the minimum setting of SSB399 and
SSB512 valve [see Tab. 17].
These are approximate figures for LPG gas appliances. A combustion
analyzer must be used to set maximum and minimum CO2 as listed in
table Tab. 16.
Maximum setting
Appliance
Number of turns from gas
valve fully wound home
SSB255 10 turns
SSB399
SSB512
Tab. 17 Number of turns for gas valve settings
5 .8

Setting frost protection

The boiler is equipped with a system frost protection function, see section
"5.5 Parameters list" for a list of all parameters and settings.
The factory default setting Frost Protection (parameter # 89) is
"DISABLED". To enable frost protection simply adjust parameter # 89 to
"ENABLE". When the frost protection is enabled, Parameter #90 (Frost
Protection Setpoint) has to be set. Parameter #90 has a default setting of
50°F and can be adjusted from 33-68 °F.
6720818454 (2016/02) US
Low Power
0 rpm
0.0 μA
Off
0 rpm
0.0 μA
Min . power CO2%
8.8-9.2 8.8-9.2
10.3-10.7
Minimum setting
Number of turns from gas
valve fully wound home
2 and ¼ turns
7 turns NA
7 turns NA
When the supply temperature falls below the value set by the parameter
#90, the boiler pump starts.
If the supply temperature continues to fall and reaches 9 °F (5 °C) below the
value set by the parameter #90 the burner will switch on at minimum power.
When the supply temperature increases to a temperature of 9 °F (5°C)
greater than the value of the parameter # 90 the burner will switch off.
Then after the post circulation time has elapsed the pump will stop
(parameter #5 adjustable from 300-900 seconds. Default is 300 seconds).
For example, parameter #90 is set at 50 °F (10 °C), when the Supply
temperature is lower than 50 °F (10 °C) the pump starts. If the supply
temperature is lower than 41 °F (5 °C) the burner starts at the minimum power.
The burner switches off when a temperature of 59 °F (15 °C) is achieved.
NOTICE: This sequence protects the boiler only from
freezing. Be sure adequate measures are in place to protect
the system.
6 Troubleshooting
WARNING: Close the gas cock prior to working on the gas
a
train or "boiler".
WARNING: Check for gas leaks after carrying out work on
a
the gas train.
WARNING: Check for leaks after carrying out work on the
a
venting system.
DANGER: Always disconnect the appliance from the
a
main power before performing any work. Disconnect the
emergency shutoff switch or disengage the heating system
circuit breaker. Take measures to prevent accidental
reconnection.
WARNING: Hot water can scald. Drain the appliance before
a
working on components that are filled with water.
6 .1

Error codes are shown on the display

If the symbol appears on the screen as follow:
70.0°F
Fig. 71
an error has occurred in the system that is displayed on the screen. The
bottom row in the display will show the description of the error occurred.
04:29 pm
SSB