Key specifications
| Control functions | parameter monitoring, actuator control, safety |
|---|---|
| Device type | control board / electronic module |
| Function | boiler control board |
| Design features | original honeywell configuration, industrial reliability |
| Model specific matching | specific to boiler model |
| Flame detection method | ionisation |
| Compatible boilers | Baxi or Westen equipment |
| Revision | different firmware or connector configuration |
| Catalogue number | 534.568.035 |
| Manufacturer code | SM11451U |
| Electrical connection | connector patterns, mounting arrangement model-specific |
| Mounting pattern | model-specific |
| Lockout on fault | lockout on failure |
201.00EUR
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Description
The Honeywell SM11451U is a control board/electronic module for gas boilers, specifically designed for Baxi or Westen equipment. It performs parameter monitoring, actuator control (pump, valves), and safety functions. This board uses ionisation flame detection and is a revision of the SM11450U, with potential differences in firmware or connector configuration. It is identified by type designation CS0171B-LS and catalogue number 534.568.035.
Further details
| Communication with components | gas valve, ionisation electrode, fan, air pressure switch |
|---|---|
| Compatibility verification | visual comparison, revision check, confirm replacement |
| Flame safeguard role | primary controller in modern wall-hung boilers |
| Ignition sequence | pre-purge, ignition, fuel admission, flame proving, lockout on failure |
| Ignition sequence management | manage pre-purge, ignition, fuel admission, flame proving, and lockout on failure |
| Interchangeability | may be interchangeable only from a certain boiler revision |
| Modulation | may modulate output based on sensor feedback |
| Output drives | fan, gas valve, ignition transformer, pump |
| Replacement verification | contact managers or provide photo of old board |
| Safety hazard mismatch | using a board intended for a different series or version can create a safety hazard |
| Safety time enforcement | pre-purge, safety, and flame-proving times differ |
| Verification required | verify exact manufacturer code and catalogue number against existing board |
Choosing and fitting
Control boards of this type are selected by matching the exact manufacturer code and catalogue number to the existing board. The electrical connection and mounting pattern are model-specific, so visual comparison of connectors, jumpers, and fuses is essential. Verify the firmware revision matches your boiler's requirements, as boards may be interchangeable only from a certain boiler revision.
Signs of failure
When such boards fail, the boiler may lock out on fault, fail to ignite, or exhibit erratic operation of the fan, gas valve, or pump. Check for visible damage, loose connections, or blown fuses. If the board is suspected, compare its markings and revision with the original to ensure correct replacement.
All specifications
| Control functions | parameter monitoring, actuator control, safety |
|---|---|
| Device type | control board / electronic module |
| Function | boiler control board |
| Design features | original honeywell configuration, industrial reliability |
| Model specific matching | specific to boiler model |
| Flame detection method | ionisation |
| Compatible boilers | Baxi or Westen equipment |
| Revision | different firmware or connector configuration |
| Catalogue number | 534.568.035 |
| Manufacturer code | SM11451U |
| Electrical connection | connector patterns, mounting arrangement model-specific |
| Mounting pattern | model-specific |
| Lockout on fault | lockout on failure |
Part numbers
| SKU | SM11451U |
|---|---|
| Additional article | 534.568.035 |
| Superseded number | SM11450U |
| Type designation | CS0171B-LS |
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