17
IMPORTANT
After servicing, complete the relevant Service
•
Interval Record section of the Benchmark
Checklist located on page 22 and 23 of this
document.
Servicing should only be carried out by
•
competent persons in the installation and
maintenance of unvented water heating
systems.
Any spare parts used MUST be authorised
•
parts.
Disconnect the electrical supply before removing
•
any electrical equipment covers.
NEVER bypass any thermal controls or operate
•
system without the necessary safety valves.
Water contained in the cylinder may be very
•
hot, especially following a thermal control failure.
Caution must be taken when drawing water from
the unit.
SPARE PARTS
A full range of spare parts are available for the
cylinder range (Table 5 Page 18). Refer to the
technical data label on the unit to identify the model
installed and ensure the correct part is ordered. You
will need to quote the serial number, which is printed
on the data label.
FAULT FINDING
The fault finding chart (Table 4 Page 17) will enable
operational faults to be identified and their possible
causes rectified. Any work carried out on the cylinder
unvented water heater and its associated controls
MUST be carried out by a competent installer for
unvented water heating systems. In case of doubt
contact
service support (see contact details on back
page).
WARNING
DO NOT TAMPER WITH ANY OF THE SAFETY VALVES
OR CONTROLS SUPPLIED WITH THE CYLINDER AS
THIS WILL INVALIDATE ANY GUARANTEE.
FAULT FINDING & SERVICING
Table 4: Fault Finding Chart
Fault
Possible Cause
Remedy
No hot water flow
Mains supply off
Check and open stop cock
Strainer blocked
Turn off water supply. Remove strainer and
clean
Cold water combination valve incorrectly
fitted
Check and refit as required
Water from hot tap
is cold
Direct immersion heater not switched on Check and switch on
Direct immersion heater thermal cut-out
has operated
Check, reset by pushing button on thermostat
Indirect programmer set to central heat-
ing only
Check, set to domestic hot water programme
Indirect boiler not working
Check boiler operation. If fault is suspected
consult boiler manufacturer’s instructions
Indirect thermal cut-out has operated
Check, reset by pushing button on thermostat
Check operation of indirect thermostat
Indirect motorised valve not connected
correctly
Check wiring and/or plumbing connections to
motorised valve
Water discharges
from expansion
valve
INTERMITTENTLY
Expansion vessel charge pressure has
reduced below 3.5bar, or set to high
See Maintenance section for re-charging of
expansion vessel procedure
CONTINUALLY
cold water combination valve pressure
reducer not working correctly.
Expansion valve seat damaged
Check pressure from cold water combination
valve. If greater than 3.5bar replace pressure
reducing valve
Remove expansion valve cartridge, check
condition of seat. If necessary fit new expansion
valve
Water discharges
from T&P relief
valve
Thermal control failure
NOTE: water will be very hot
Switch off power to immersion heater(s) and
shut down boiler.
DO NOT
turn off water supply. When discharge
stops check all thermal controls, replace if faulty
Milky water
Oxygenated water
Water from a pressurised system releases
oxygen bubbles when flowing. The milkiness will
disappear after a short while
