Fault Finding And Diagnostics; Central Heating Trouble Shooting Guide - Bosch Worcester Greenstar HIU E Installation And Maintenance Instructions Manual

9

Fault finding and diagnostics

Basic checks
▶ Ensure that there is 230Vac power supply and the polarity is correct to the appliance.
▶ Ensure that the appliance/controller settings and functionality are operating correctly.
9.1

Central heating trouble shooting guide

Problem Possible cause
No heat output from Air in the heating system
HIU
Central heating pump faulty
Pump setting set too low
Central heating filter blocked
District heating filter blocked
Faulty central heating flow sensor
Faulty central heating return sensor ▶ Replace sensor
HIU Control unit incorrectly set or
faulty
Room controller incorrectly set or
faulty
Faulty central heating control valve
or dirt inside valve body causing
low flow or no flow through district
supply circuit
District supply temperature too low ▶ Check that the district supply temperature is correct for the required heat output.
District flow rate is too low
District supply differential pressure
is too low
Central heating flow HIU Control unit incorrectly set or
temperature too low faulty
Room controller incorrectly set or
faulty
Outdoor sensor positioned
incorrectly
District supply temperature too low ▶ Check that the district supply temperature is correct for the required heat output.
District flow rate is too low
District supply differential pressure
is too low
Table 32 Central heating trouble shooting
6 720 808 928 (2017/06)
Possibly solution/check
▶ Vent the heating system fully at the radiator manual air vents, for indirect unit.
▶ Vent the HIU fully at the manual air vents. Ensure system pressure is between 1 - 2 bar
▶ Check that there is power to the pump  section 6.3 for instructions on venting the
appliance.
▶ Replace pump if necessary.
▶ Adjust pump to correct setting.  section 6.6
▶ Clean filter (direct and injection models only)
▶ Clean filter
▶ Replace sensor
▶ Ensure that the flow temperature set-point is set correctly on the HIU controller.
 section 6.4.
▶ Replace control unit if necessary.
▶ Check that room controller is set correctly and is calling for heat.
▶ Replace room controller if necessary.
▶ Check that control valve is functioning correctly.  section 6.5.
▶ Perform re-calibration of control valve. See section 6.4.
▶ Open control valve manually using CH rotary switch on HIU control unit.  section 6.4.
▶ Replace control valve if necessary
 Section 6.11, Central heating performance charts
▶ Check that the district flow rate is correct for the required heat output.
 Section 6.11, Central heating performance charts
▶ Check that the supply differential pressure is correct for the required heat output.
 Section 6.11, Central heating performance charts
▶ Adjust the flow regulating valves at the heat interface unit to obtain the correct
differential pressure.
▶ Increase the supply differential pressure on the system.
▶ Adjust HIU control unit.  section 6.4
▶ Replace if necessary
▶ Adjust room controller.
▶ Replace if necessary
▶ Position outdoor sensor correctly
 Section 6.11, Central heating performance charts
▶ Check that the district flow rate is correct for the required heat output.
 Section 6.11, Central heating performance charts
▶ Check that the supply differential pressure is correct for the required heat output.
 Section 6.11, Central heating performance charts
▶ Adjust the flow regulating valves at the heat interface unit to obtain the correct
differential pressure.
▶ Increase the supply differential pressure on the system.
Fault finding and diagnostics
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