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Worcester Bosch Greenstar 4000 Combi fault 281

Pump stuck or running in air

Gas boiler

What it means

Fault category B. Pump stuck or running in air.

Likely causes

  1. Low primary system water pressure
  2. Air in the system
  3. Poor circulation in heating system
  4. Faulty hydraulic connections to pump
  5. Faulty pump wiring or operation

Where to start

  1. Check primary system water pressure
  2. Check for air in the system and vent the pump
  3. Check for circulation within heating system

The full answer, free

  • 22 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 74), right under the answer
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Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.

From the Worcester Bosch manual for the Greenstar 4000 Combi. Check the model on the data plate before you order parts.

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