CBFF - Central Heating

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The flashcards below were created by user zenken79 on FreezingBlue Flashcards.


  1. DHW is ok but central heating is not. The fault can only be at:
    • The diverter valve which is seized or sticking,
    • microswitches,
    • flow switch,
    • CH thermostat and thermistors,
    • PCB.
  2. CH not at temperature.
    • Sludge/scale build up in main heat exchanger often causing kettling.
    • pump speed slow due to sediment/sludge etc.
  3. No CH/ DHW is ok.
    • Room thermostat faulty so no signal to combi boiler.
    • programmer set incorrectly.
    • diverter valve faulty.
    • dripping hot water draw off point preventing diverter valve moving.
    • microswitches faulty.
    • thermistor connections/terminals are dirty/loose.
    • open circuit/infinity caused by water ingress.
    • thermistor lost calibration.
    • thermostat failed
    • thermostat lost calibration.
    • thermostat contact points worn/ burnt out/pitted.
    • thermocouple phial out of position.

Card Set Information

Author:
zenken79
ID:
313700
Filename:
CBFF - Central Heating
Updated:
2016-01-04 09:26:11
Tags:
gas
Folders:
fault finding
Description:
Combi boiler fault finding central heating
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