Central Heating Repair

This article is about Central Heating systems using hot water as a heat-carrying medium. (Warm-air systems are sometimes found in the UK but their design and installation is not covered here. There is a discussion on updating existing warm-air systems here)

The article is about diagnosing and fixing a faulty central heating system.

There are separate articles about:

• Central Heating Design which will help you understand what sort of system you have
• Central Heating Operation for help operating a working CH system.

This article is a skeleton: the main points to be covered are listed but some or all still need to be expanded

Fault-finding

• No CH or DHW
• No CH, DHW OK
  • conventional
  • combi
• CH OK, no DHW
  • conventional
  • combi
• DHW OK, some parts of CH not working
  • rad(s) compeletely cold
    • balancing
    • stuck TRV
    • completely full of air
  • rad(s) lukewarm
    • balancing
    • faulty TRV
  • rad(s) cold at top
    • bleeding
  • rad(s) cold at bottom
    • sludge

rads constantly need bleeding

• air or hydrogen in system? (lighter test - with care!)
  • corrosion:
    • inhibitor?
    • vented system? - pumping over?
  • air
    • pinhole leaks?
    • vented system? - pumping over?