Kohler Mira Zest User manual

1
These instructions are to be left with the user
Installation and User Guide
ELECTRIC SHOWER
MIRA ZEST

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CONTENTS
Introduction ............................................................................................. 3
Important Safety Information ................................................................. 4
Pack Contents ......................................................................................... 6
Specifications .......................................................................................... 7
Dimensions .......................................................................................... 7
Wiring Diagram .................................................................................... 7
Plumbing .............................................................................................. 8
Electrical .............................................................................................. 8
Standards and Approvals ..................................................................... 8
Flow Rate Graph .................................................................................. 8
Installation Requirements ...................................................................... 9
Plumbing .............................................................................................. 9
Electrical ............................................................................................ 11
Installation ............................................................................................. 12
Commissioning ..................................................................................... 14
Operation ............................................................................................... 16
Fault Diagnosis ..................................................................................... 18
Maintenance .......................................................................................... 22
Cleaning ............................................................................................. 22
Cleaning the Inlet Filter ...................................................................... 22
Relief Valve Assembly - Resetting .................................................... 23
Spare Parts ............................................................................................ 24
Spare Parts List ................................................................................. 24
Spare Parts Diagram .......................................................................... 25
Notes ...................................................................................................... 26
Customer Service .................................................................... Back Page

3
INTRODUCTION
Recommended Usage
Domestic
Light Commercial
Heavy Commercial
Healthcare
X
X
W
W
If you experience any difficulty with the installation or operation of your new shower
control, then please refer to "Fault Diagnosis", before contacting Kohler Mira Limited.
Our telephone and fax numbers can be found on the back cover of this guide.
Thank you for purchasing a quality Mira Zest Electric Shower. To enjoy the full potential
of your new shower, please take time to read this guide thoroughly, and keep it handy
for future reference.
Mira Zest electric showers have separate controls for power selection and for
temperature/flow adjustment. A unique flow regulator stabilises any temperature
changes caused by water pressure fluctuations, which can result from taps being
turned on or off or toilets being flushed.
Products covered by this guide:
Mira Zest 7.5 A 7.5 kW 240 V AC (6.9 kW 230 V AC) heater. Available in a
white finish.
Mira Zest 8.5 A 8.5 kW 240 V AC (7.8 kW 230 V AC) heater. Available in a
white finish.

4
Warning!
1. Products manufactured by us are safe and risk-free, provided that they are
installed, used and maintained in good working order, in accordance with our
instructions and recommendations.
2. THIS APPLIANCE MUST BE EARTHED.
3. In accordance with ‘The Plugs and Sockets etc. (Safety) Regulations’ in force at
the time of installation, this appliance is intended to be permanently connected
to the fixed electrical wiring of the mains system.
4. DO NOT twist the individual cable cores of the live and neutral conductors, as
this will prevent them from entering the terminal block.
5. Make sure that any pipework that could become frozen is properly insulated.
6. DO NOT operate this appliance if it is frozen. Allow the appliance to thaw before
using. The shower unit must not be fitted where it may be exposed to freezing
conditions.
7. DO NOT fit any form of outlet flow control as the outlet acts as a vent for the tank
body. Only Mira Showers recommended outlet fittings should be used.
8. If water leaks from the pressure relief valve, maintenance will be required before
the appliance can be safely used.
9. There are no user-serviceable components beneath the cover of the appliance.
Only a competent tradesperson should remove the cover.
10. If any of the following conditions occur, isolate the electricity and water supplies
and refer to To contact us, on the back page of this guide.
• The cover is not correctly fitted and water has entered the appliance
case.
• The case is damaged.
• The appliance begins to make an odd noise, smell or smoke.
• The appliance shows signs of a distinct change in performance, indicating
a need for maintenance.
• The appliance is frozen.
11. Isolate the electrical and water supply before removing the cover.
12. Mains connections are exposed when the cover is removed.
13. Refer to the wiring diagram before making any electrical connections.
14. Make sure all electrical connections are tight, to prevent overheating.
15. This product is not suitable for areas with very high humidity (i.e steam rooms).
Please consult your installer.
IMPORTANT SAFETY INFORMATION

5
Caution!
1. Read all of these instructions and retain this guide for later use.
2. Pass on this guide in the event of change of ownership of the installation site.
3. Follow all warnings, cautions and instructions contained in this guide, and on or
inside the appliance.
4. The electrical installation must comply with the “Requirements for Electrical
Installations” (commonly referred to as the IEE Wiring Regulations), or any
particular regulations and practices, specified by the local electricity supply
company in force at the time of installation. The installation should be carried out
by an electrician or contractor who is registered, or is a member of, an association
such as:
• National Inspection Council for Electrical Installation and Contracting
(NICEIC), throughout the UK.
• The Electrical Contractors Association (ECA), England and Wales.
• The Electrical Contractors Association of Scotland (ECAS).
5. This is a high power unit; it is essential to contact your electricity supply company
to ensure that the electricity supply is adequate for the purpose.
6. The plumbing installation must comply with the requirements of UK Water
Regulations/Bye-laws (Scotland), Building Regulations or any particular regulations
and practices, specified by the local water company or water undertakers. The
installation should be carried out by a plumber or contractor who is registered, or
is a member of, an association such as:
• Institute of Plumbing (IOP), throughout the UK.
• National Association of Plumbing, Heating and Mechanical Services
Contractors (NAPH & MSC), England and Wales.
• Scottish and Northern Ireland Plumbing Employers’ Federation (SNIPEF),
Scotland and Northern Ireland.
7. This appliance is not thermostatic and can produce scalding temperatures if not
operated in accordance with the instructions given in this manual.
8. Anyone who may have difficulty understanding or operating the controls of any
shower should be attended whilst showering. Particular consideration should be
given to:
• the young
• the elderly
• the infirm
• the disabled
• anyone who suffers from a medical condition that can result in temporary
incapacity (e.g. epilepsy or blackouts).
• anyone inexperienced in the correct operation of the controls.
9. When this appliance has reached the end of its serviceable life, it should be
disposed of in a safe manner, in accordance with current local authority recycling,
or waste disposal policy.

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PACK CONTENTS
¸3 x Wall Plugs
¸3 x Fixing Screws
¸1 x Mira Zest Electric Shower
Documentation
¸1 x Installation & User Guide
¸1 x Installation Template
¸1 x Guarantee Brochure
ZTick the appropriate boxes to familiarise yourself with the part names and to
confirm that the parts are included.

7
SPECIFICATIONS
205 mm 103 mm
53 mm
310 mm
Dimensions
Wiring Diagram

8
Plumbing
1. Minimum maintained inlet pressure for satisfactory operation: 0.7 bar (70 kPa)
2. Maximum static inlet pressure: 10 bar (1000 kPa)
3. Minimum static pressure to keep the flow valve closed: 0.5 bar (50 kPa)
Electrical
1. The appliance requires a 40 Amp fuse.
2. The terminal block will not accept cable larger than 10 mm2.
Standards and Approvals
1. This Mira Zest shower complies with all the relevant directives for CE marking.
Flow Rate Graph
1. These curves are for the specified outputs at 240 V.
2. All appliance heating elements have a manufacturing tolerance. Flow rates may
be above or below those shown on the flow rate graph.
3. The left-hand axis shows temperature rise.
Temperature rise = (Showering temperature) - (Supply water temperature)
Example: For the Mira Zest 8.5 kW on full power setting with an incoming water
supply at 10°C and a showering temperature at 42°C, the temperature rise is 32°C.
The flow rate is therefore, 4 l/min.
Flow Rate (l/min)
Temperature Rise (°C)
7.5 kW
8.5 kW

9
Plumbing
1. The Mira Zest 7.5 kW and 8.5 kW electric showers are designed to operate with
a minimum maintained inlet pressure of 0.7 bar (70 kPa) up to a maximum
static inlet pressure of 10 bar (1000 kPa).
2. The appliance is normally connected to the cold water mains-fed supply. However,
the water supply can be taken from a cold water storage cistern, provided there
is a minimum maintained inlet head of water of 7 metres (the vertical distance
from the base of the cold water storage cistern to the shower fitting handset). To
reduce pressure losses and fluctuations, the cistern-fed water supply must be
independent from other supply draw-offs, and should avoid long horizontal pipe
runs and use swept bends rather than 90° elbows. For further advice please
refer to the back cover of this guide for Mira Showers contact telephone and fax
numbers.
3. The appliance is suitable for installation within the shower area. It is fitted with a
pressure relief device and must be positioned over a water catchment area with
the controls at a convenient height for the user. The shower fitting should be
positioned so that it discharges down the centre line of the bath, or across the
opening of a shower cubicle, and must be directed away from the appliance.
4. The appliance is fitted with an inlet connector assembly that is designed to accept
plumbing supplies from the top or bottom. The water supply can be fed with
15 mm pipe or 10 mm microbore pipe, suitably adapted into the inlet connector
assembly. If 10 mm microbore is used, then an allowance for increased pressure
loss must be made to ensure that the minimum maintained inlet pressure is
achieved.
5. Do not fit the appliance to the wall and tile up to the case. The appliance must be
fitted onto a finished flat and even wall surface. Otherwise, difficulty may be
encountered when fitting the cover, and subsequent operation of the unit could
be impaired (small pillars moulded on to the back of the case allow air circulation).
6. Use only the inlet connector assembly supplied with the appliance. Do not use
any other types of fitting.
7. Refrain from applying excessive force when making any connections. Always
provide mechanical support when making the plumbing connections.
8. This appliance is not designed to be plumbed directly from the rear. For a rear-
entry supply, add an elbow to the supply pipe and connect it as a rising or falling
supply.
9. Do not install the appliance in a position where it may become frozen. The
shower unit must not be fitted where it may be exposed to freezing conditions.
The shower unit must not be used if you suspect it may be frozen.
INSTALLATION REQUIREMENTS

10
25 mm
minimum
Spillover
Level
Hose Retaining
Ring
10. We recommend that a non-restrictive (free-flowing) isolating valve is fitted in the
cold water supply pipe to allow the complete maintenance of the appliance. Do
not use a valve with a loose washer plate (jumper) as this can lead to a build up
of static pressure.
11. To avoid damage to the case when soldered fittings are used, pre-solder the
pipework and fittings before connecting them to the inlet stub.
12. Supply pipework MUST be flushed to clear debris before connecting the appliance.
13. The appliance is fitted with a 1/2" BSP male outlet thread, to accept a Mira Zest
shower hose.
14. When installed in very hard water areas (above 200 ppm temporary hardness)
your installer may advise the installation of a water treatment device, to reduce
the effects of limescale formation. Appliance malfunction due to excessive
limescale formation is not covered by the manufacturer’s guarantee. Your local
water company will be able to advise on the hardness of water in your area.
15. A hose retaining ring is supplied to
prevent the handset from dropping
below the spillover level of the bath or
shower, which could lead to
contamination from back-siphonage.
The supplied hose retaining ring
should meet the majority of user
requirements for shower installations
with flexible outlet fittings. However,
there will be occasions when the hose
retaining ring will not provide a suitable
solution. In these instances an outlet
double checkvalve must be fitted. This
will increase the required supply
pressure typically by 0.1 bar (10 kPa).
Double checkvalves, fitted in the inlet
supply to the appliance, cause a
pressure build-up, which could exceed
the maximum static inlet pressure for
the appliance.
16. Avoid layouts where the shower hose will be sharply kinked. This may reduce
the life of the hose.

11
Electrical
1. In a domestic installation, the rating of the electricity supply company fuse and
the consumer unit must be adequate for the additional demand. This is a high-
power appliance, and it is essential to contact your electricity supply company to
ensure that the supply is adequate for the appliance. Voltage drop due to local
heavy demand will reduce the performance of the shower.
2. The appliance must be earthed by connecting the supply-cable earth conductor
to the earth terminal.
Supplementary bonding: Within the bathroom or shower room, all accessible
conductive parts of electrical equipment and extraneous conductive parts that
are likely to introduce earth potential, must be electrically bonded to earth using
a minimum cable size of 4.0 mm2if the cable is not mechanically protected
(2.5 mm2if mechanically protected).
3. The minimum cable size (cross-sectional area) must conform to BS7671
4. To obtain full advantage of the power provided by this unit, use the shortest
possible cable route from the consumer unit to the shower.
5. A 30 mA residual current device (RCD) should be fitted. This may be part of the
consumer unit or a separate unit.
Plumbing and Electrical Schematic
6. A separate, permanently connected
supply must be taken from the
consumer unit to the appliance through
a double-pole switch, which has a
minimum 3 mm contact separation.
The switch can be a ceiling mounted
pull-cord type within the shower room,
or a wall mounted switch in an
adjacent room.
7. DO NOT twist the individual cable
cores of the live and neutral
conductors, as this will prevent them
from entering the terminal block.
8. DO NOT exert strain on the terminal
block.
9. DO NOT turn-on the electrical supply
until the plumbing has been completed.

12
Inlet Connector
INSTALLATION
Warning! Isolate the electrical and water supplies before installing the shower.
1. Decide on a suitable position for the appliance (minimum distance of 200 mm
from the ceiling to allow for cover fit and removal). The position of the appliance
and the shower fittings must provide a minimum gap of 25 mm between the spill-
over level of the shower tray/bath and the handset. This is to prevent
backsiphonage
2. Put the installation template on the wall and mark the positions of the top two
fixing holes. Ensure that there are sufficient lengths of supply pipe and electrical
cable to reach the connection points as shown on the template.
3. Remove the installation template and drill the top two fixing holes. Insert the
supplied wall plugs.
Caution! Do not drill into cables or pipes in the wall.
4. Thoroughly flush the supply pipe.
5. On the shower, turn both knobs to the
full anti-clockwise position.
6. Remove the three screws that hold the
cover on the shower and remove the
cover.
7. Remove the service tunnel from the
shower.
8. Determine the direction of the incoming
water supply: falling (entering the
shower from the top), or rising (entering
the shower from the bottom).
Do not use an incoming supply
entering the shower directly from the
back. Add an elbow to the supply pipe
and connect it as a rising or falling
supply.
9. Rotate the inlet connector to suit the
direction of the incoming water supply.
Screws
Cover
Service Tunnel
Shower
Screw

13
10. The case has thinned sections that can
be removed to allow entry of the supply
pipe and electrical cables. Remove the
top thinned section of the case for a
falling supply, or remove the bottom
thinned section of the service tunnel
for a rising supply.
11. Do not remove any case if the
electrical cables enter from the back.
12. Secure the shower to the wall loosely
through the top two fixing holes, using
the supplied screws.
13. Mark the position of the bottom fixing
hole.
14. Remove the shower from the wall. Drill
the bottom fixing hole and insert the
supplied wall plug.
15. Thoroughly flush the mains-fed cold
water supply pipe.
Caution! The supply must be clean
and free from debris BEFORE
connecting the appliance.
16. Replace the shower on the wall and
secure through the three fixing holes,
using the supplied screws.
17. Connect the inlet supply pipe to the
inlet connector using a 1/2” BSP nipple
with compression nuts and olives
(shown) or a push-fit connector.
Thinned
Section
Thinned
Section
Service Tunnel
Screws
Inlet
Connector
Compression
Nut
Olive
1/2” BSP Nipple
Olive
Compression
Nut
Inlet Supply Pipe

14
Spindle
Screws
Cover
Service Tunnel
Screw
18. Bring the electrical cables into the
case.
19. Strip back sufficient of the outer cable
insulation to enable routing to terminal
block.
20. Fit an earth sleeve to the earth wire.
21. Loosen the screws in the terminal
block and insert the bare wires into the
clamps.
L (Live) = Brown wire
E (Earth) = Green sleeved wire
N (Neutral) = Blue wire
Note! Do not twist the cores of the
wires or strain the cables to make them
reach the terminal block.
22. Connect the conductors firmly into the
terminal block. Make sure that the bare
cores of each conductor are securely
trapped within each conductor clamp.
23. If necessary, fit an earth bonding
clamp to the supply pipe and ensure
that the bonding complies with the
relevant regulations in force at the time
of installation.
24. Replace the service tunnel.
25. Replace the cover. If the cover does
not fit easily, rotate the knobs slightly
so that they fit onto the spindles. Do
not force the cover.
26. Tighten the three cover screws.
L
N
Electrical
Cables
Terminal
Block
Outlet
Connector
Cold Water Supply Pipe/
Inlet Connector

15
If you are unsure how electric showers work, please read through the Operation
section before continuing.
1. Make sure that the TOP control knob is in the 'STOP' position and that the
electrical supply has been isolated.
2. Turn the BOTTOM control knob fully anticlockwise to the full cold position.
3. Turn the water supply fully on at the isolating valve, check that water is not
leaking from the bottom of the case.
4. Switch on the electrical supply at the double pole switch.
5. Turn the TOP control knob to the 'LOW' position. Check that water flows freely
from the shower within a few seconds. If not, refer to the Maintenance section.
The water from the handset will be at full force and at a cool temperature.
6. Turn the BOTTOM knob slowly clockwise. As the knob is rotated the flow will be
reduced and the temperature will remain cool - this shows that the flow regulator
assembly is operating correctly. Return the knob anticlockwise to full cold position.
7. Turn the TOP knob to the 'MEDIUM' position. The temperature of the water
should rise slightly. Allow a few seconds for the warm water to reach the handset
- this shows that the 'MEDIUM' power setting is operating correctly.
8. Turn the TOP knob to the 'HIGH' position. The temperature of the water will rise
further - this shows that the full power setting is operating correctly.
9. Set the shower temperature by rotating the BOTTOM knob as necessary. Turn
the knob clockwise for hotter water and anticlockwise for cooler water.
Note! When the temperature is changed the flow rate will change.
10. When the required temperature is reached, turn to the STOP position to stop the
flow. Water may continue to flow from the handset for a few moments during
shut-down, as water is purged from the tank. Isolate the power at the double pole
switch.
11. A small amount of water may be retained in the shower fitting after the shower
control has been turned off. This may drain over a few minutes.
Note! A slight hissing sound may be heard from the appliance during operation.
High mains water pressure and high shower temperatures will effect the tone.
This is quite normal when the shower is in use.
COMMISSIONING

16
Advice to Users
Note! Read the Important Safety Information section first.
Warning! The spray plate holes must be kept clear. The spray plate should be regularly
removed and cleaned in descalent. Lack of regular spray plate cleaning will lead to
poor performance and cause early failure of the appliance. See the shower fittings
User Guide for more information.
1. Electric showers work by taking in cold water and passing it over the heating
elements contained in the tank inside the shower.
2. The showering temperature is adjusted by turning the temperature control knob,
which varies the flow of cold water across the elements. The slower the rate of
flow, the warmer the water, and vice versa. The holes in the spray plate of the
shower handset should always be kept clean to maintain a consistent flow and
stable shower temperatures.
3. The appliance is designed to stabilise temperature changes caused by water
pressure fluctuations. These fluctuations can be caused by taps being turned on
or off, or toilets being flushed. Under such conditions, average shower temperatures
will be held within a 6°C range, provided that the minimum required pressure is
maintained.
4. Seasonal changes in the temperature of the incoming cold water supply and/or
fluctuations in mains electrical voltage will effect the temperature of the water.
Adjust the temperature knob as necessary to compensate.
5. The shower requires a minimum maintained/running pressure of 0.7 bar (70 kPa)
to operate. At pressures above 0.7 bar (70 kPa), the shower will minimise the
temperature fluctuations caused when other draw-off points are used. If the flow
rate drops below an acceptable level, the heating element inside the shower will
turn off, resulting in a cold shower.
6. If the water temperature reaches an unsafe level, the thermal switch assembly
turns off the heating elements. As the water temperature falls the elements will
be turned on. The switch will cycle on/off/on if the flow rate is not increased and
the temperature of the shower reduced.
7. Check the shower temperature before entering the shower. The previous user
may have selected a different temperature setting.
8. When the shower is first turned on, or the temperature setting is changed, there
will be a slight delay before the water temperature changes.
OPERATION

17
Operation Instructions
To turn the shower on
1. Switch on the electrical supply at the
double pole switch.
2. Turn the power knob to High. Wait
15-20 seconds for warm water to reach
the handset.
For electrical economy, set the power
knob to Medium. This setting will
provide sufficient power when the
supply water temperature is warmer,
such as in the summer.
For an unheated shower, set the power
knob to Low.
To set the shower temperature
1. Set the shower temperature by rotating
the temperature knob as necessary.
Turn the knob clockwise for hotter
water and anticlockwise for cooler
water. Wait 10–15 seconds for the
adjusted temperature to reach the
handset.
Note! It is normal for the flow rate to
change when the temperature is
changed.
Note! If the water temperature cycles
between hot and cold, the temperature
is set too high. This is causing the
thermal switch to turn off the heating
element to reduce the water
temperature. Turn the temperature
knob anticlockwise to reduce the water
temperature.
To turn the shower off
1. Turn the power knob to Stop.
Note! A small amount of water may
continue to flow from the handset for
a few moments.
2. Switch off the electrical supply at the
double pole switch.

18
No water or very low
flow rate.
Clear the blockage or replace
the hose or handset.
The hose or handset is
blocked.
FAULT DIAGNOSIS
Shower is too hot.
Turning the
temperature knob
does not affect the
water temperature.
The water continues
to flow when the
double pole switch is
turned off.
The incoming water is
warmer in the summer, so
the shower power setting is
too high.
The handset sprayplate is
blocked.
The handset sprayplate is
blocked.
Broken diaphragm.
Turn the power knob to
Medium and adjust the
temperature knob until the
desired temperature is
reached.
Regularly clean the handset
sprayplate. Refer to the
Maintenance section of the
handset manual.
Remove and clean the handset
sprayplate. Refer to the
Maintenance section of the
handset manual. If the fault
persists, contact the shower
installer.
Contact your installer to
replace the flow valve
assembly.
Malfunction Cause Remedy
Shower is too hot
during the summer.
The troubleshooting information tabled below gives you details on probable causes
and remedies should difficulties be encountered whilst the shower is in operation.
Warning! There are no user serviceable components beneath the cover of the
appliance.
ONLY A COMPETENT TRADESPERSON SHOULD REMOVE THE FRONT COVER!
The handset sprayplate is
blocked.
Clean the handset sprayplate.
Refer to the Maintenance
section of the handset manual.
The incoming water supply
stop valves, or the
appliance isolating valve, is
closed.
Open the stop/isolating valve
completely.
(Continued. . . .)

19
Malfunction Cause Remedy
No hot water from
shower, with the
knobs in any
position.
Other water outlets are
being used during
showering, causing the
water pressure to drop
below the minimum
required.
Temperature cycles
between hot and
cold.
The temperature is set too
high. This is causing the
thermal switch to turn off
the heating element to
reduce the water
temperature.
The power is off at the
double pole switch.
Switch on the power at the
double pole switch.
Renew the fuse or reset the
MCB/RCD. If the fault persists,
contact the shower installer.
Make sure the other water
outlets, such as the washing
machine or dishwasher, are not
in use during showering.
Make sure that the incoming
water supply stop and the
isolating valve are completely
open. If the fault persists,
contact the shower installer.
Contact installer to replace
faulty parts.
Failure of pressure switch,
micro switch or thermal
switch.
Turn the temperature knob
anticlockwise to reduce the
water temperature.
The water pressure is
below the minimum
required.
ALL OF THE FOLLOWING REMEDIES MUST ONLY BE
PERFORMED BY A COMPETENT TRADESPERSON!
No hot water from
shower, with the
knobs in any
position.
Insufficient water supply
pressure.
Failure of the pressure
switch, microswitch or
thermal switch.
Contact the local water
authority.
Check the continuity of the
switches, using a suitable
continuity measuring device.
Replace the switches as
necessary.
Check the integrity of the
internal wiring.
An internal wiring
connection has failed.
One of the heater tank
elements has failed.
Replace the heater tank.
Switch assembly
diaphragm fault, water
dripping from the unit.
Replace switch assembly.
The fuse is blown or the
MCB/RCD has been
tripped, indicating a
possible electrical fault.