Fault Finding & Servicing - Jet 120i Installation & Servicing Instructions Manual

Fault Finding & Servicing
Important
• After servicing, complete the relevant Service
Interval Record section of the Benchmark
Checklist located on pages 20 and 21 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.
Fault
No hot water
Water from hot taps
is cold
Water discharges
from expansion relief
valve
Water discharges
from the T&P valve
intermittently
Water discharges
from the T&P valve
continually
Milky water
Table 04: Fault Finding Chart
Possible cause
1. Mains water supply off.
2. Strainer blocked.
3. Cold water combination valve
incorrectly fitted.
1. Back up immersion heater not
switched on.
2. Back up immersion heater
thermal cut-out has tripped.
3. Indirect programmer set to
central heating only.
4. Indirect boiler not working.
5. Indirect thermal cut-out has
tripped.
6. Indirect motorised valve not
connected correctly.
1. Intermittently. Air volume in the
cylinder has reduced
2. Continually. 3 bar pressure
reducing valve is not working
correctly.
3. Continually. Expansion valve
seat damaged.
1. Air volume in the cylinder has
reduced
2. 8 bar expansion relief valve
faulty.
1. Thermal control failure. Note
water will be very hot.
1 Oxygenated water.
Spare Parts
A full range of spare parts are available for the
cylinder range (Table 05, 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 04, below) will enable
operational faults to be identified and their possible
causes rectified. Any work carried out on the
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.
Remedy
1. Check and open stop cock.
2. Turn off water supply. Remove strainer and clean (
see page 31).
3. Check and refit as required.
1. Check and switch on.
2. Check. Reset by pushing button (Figure 10, page 14).
3. Check. Set domestic to a hot water programme.
4. Check boiler operation. If fault is suspected consult
boiler manufacturers instructions.
5. Check. Reset by pushing button. Check operation of
indirect thermostat (Figure 10, page 14).
6. Check wiring and/or plumbing connections to
motorised valve (see Figures 8 & 9, page 13).
1. See page 16 for details on how to test and recharge.
2. Check pressure from 3 bar pressure reducing
valve. If greater than 3 bar replace pressure reducing
cartridge.
3. Remove expansion relief cartridge from 8 bar
pressure relief valve and check seating, if necessary fit
new cartridge.
1. See page 16 for details on how to test and recharge.
2. Check valve and replace if necessary
1. Switch off power supply to immersion heater(s) and
shut down the boiler. DO NOT turn off the water supply.
When discharge stops check all thermal controls,
replace if faulty.
1. Water from a pressurised system releases oxygen
bubbles when flowing. The milkiness will disappear
after a short while.
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