12
CYLINDER FAULT FINDING
PROBLEM
POSSIBLE CAUSE
REMEDIATIVE ACTION
Water is visible at tundish
Potential discharge from T&P valve
Follow tundish/T&P fault finding
Potential discharge from Expansion relief
valve due to fault at PRV
Follow inlet control set fault finding
Back pressure from system
Check all cold connections into mixer
outlets are fed from the balanced cold
service from the inlet control valve. If
not, additional PRV’s must be fitted.
Expansion relief valve opens when
cylinder is heated
Possible fault at Expansion Vessel
Follow expansion vessel fault finding
Cylinder appears to be leaking from
inside the steel case
Loose cylinder connection - notably from
hot water outlet
Check all connection points including
the immersion heaters and the hot
outlet to ensure that these are not
leaking, and remake joints if necessary.
Noise when operating tap or shower
Vibrating/insecure pipework
Ensure that all pipework is secured to
the wall with pipe clips as appropriate.
Reduced water flow
Possible external water works being
carried out
Check with local authorities and wait
for works to be completed
Lodged debris from mains at Inlet control
set or PRV sticking
Strip & clean PRV/inline filter, or
replace inlet control set.
No hot water available
Possible immersion heater failure
Follow immersion heater fault finding
EXPANSION VESSEL FAULT FINDING
PROBLEM
POSSIBLE CAUSE
REMEDIATIVE ACTION
Discharge of water from relief valve
into tundish
Expansion Vessel is undersized
Vessel needs resizing and installing by
a qualified heating engineer.
Pre-charge set incorrectly on vessel
installation
Pre-charge requires setting when the
system is depressurised according to
manufacturer’s recommendations.
Vessel membrane is ruptured and may
require replacement
Check schrader valve for leaks or
damage. Replace vessel if necessary
Membrane may be partially
depressurised due to losses over time and
require re-pressurisation
Check schrader valve for leaks or
damage. Have heating system serviced
and vessel repressurised or replaced.
Leak from flange or water
connection
Failure of flange plate
Replace flange plate or entire vessel
Ruptured membrane has led to internal
corrosion and has caused leak in vessel
Replace entire vessel
Vessel appears full of liquid when
system is cold
Membrane is fully depressurised
Replace membrane or entire vessel.
Check schrader valve for leaks or
damage.
Water discharges from vessel
when schrader pin is depressed for
inspection of pressure
Vessel membrane is ruptured
Replace membrane or entire vessel.
