CBFF - System water pressure low/high

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  1. Tempreature gauge - normal

    Pressure gauge - High

    The fault is with either:
    • Expansion vessel,
    • Schraeder valve,
    • Connecting pipe,
    • Domestic hot water heat exchanger, or
    • Filling loop.
  2. Tempreature gauge - High

    Pressure gauge - High
    Fault is with:

    • Limit thermostat,
    • Pump, or
    • Scaling
  3. Regular Topping Up of System
    • Excessive venting of radiators by householder
    • Leak in system at pump or radiators,unions, pipe work, heat exchanger cracked etc.
  4. Regular Topping Up of System and PRV discharges with pressure gauge low/zero when cold.
    • Undersized expansion vessel.
    • Expansion vessel lost charge naturally over time.
    • Expansion vessel diaphragm split or porous.
    • Schraeder valve faulty and letting out air.
    • PRV faulty or leaking due to obstruction at seating.
    • Pressure over 3bar, water discharge at PRV - expansion vessel undersized.
    • Vessel to pipe work connecting pipe blocked with sludge.
    • Faulty gauge. Pressure gauge reading low. PRV discharges.
    • Excessive fill pressure.
  5. Regular topping up of system/PRV discharges/system overheating.
  6. Combi boiler overheating due to scaling or sludge and a PRV discharging.
    • Combiboiler overheating due to pump failing/failed and PRV discharging.
    • Limit thermostat faulty so overheating to overheatt thermostat and PRV discharging.
    • Pump or fan over-run faulty.
    • Manual or automatic By-pass set incorrectly.
  7. System cold, PRV Discharges and High Pressure at Gauge (3 bar)
  8. Domestic hot water heat exchanger leaking across to primary system.
    Filling loop attached and isolators letting by.
Card Set:
CBFF - System water pressure low/high
2016-01-03 23:01:13
Fault finding
CBFF - System water pressure low/high
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