trevi boost installation
Built-in Shower Mixer
Exposed Shower Mixer
mixed out
Fig. 1
Dimensions (in millimetres) may vary within permitted tolerances.
Please read these instructions
carefully before commencing
installation and familiarise
yourself fully with the
assembly details, the exploded
diagram (Fig. 2) and list of
components which are
numbered and referred to in
the instructions.
Dimensions of the mixers are
shown in Fig. 1.
! tj$$&&i; j
. . . .**. .
. . .**. .
. . . . ...‘..
. . .
i.................____ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fig. 2
- illustrated in installation
configuration 6 (See Fig. 8)
No. Description
Part No.
cover plate for Built-In
la cover_ plate_ complete
for Built-In ~__0964066-2
cover plate sealing rings for Built-In
foam aasket for Built-In
cover plate fixing screw for Built-In
0961137-cap for volume control~______
handle 096258500
screw for volume control handle
cap for temperature control handle 096307300
screw for temperature control handle-.91841600
0962599-10 volume control handle carrier 096165900
11 clutch cover
1 la clutch cover sealing washer
12 clutch cover fixino screws
12a clutch complete
13 clutch drive shaft
14 gears
for clutch
cOne screw
---.-- ~~~--__~~~
No. ’ Description
Part No.
18 booster cartridge
18a set of ‘0’ rings and screens
for booster cartridae
19 shroud spacer washers (rubber)
20 temperature handle carrier
21 temperature handle stop
22 blankino oluo
23 volumecontrol handle
0962586-24 temperature control handle
0963347-25 mounting template/plaster guard
for Built-In
26 mounting template/plaster guard screws
for Built-In
27 cover for Exposed
27a cover complete for Exposed
0990953-28 plastic trims for Exposed cover
28a plastic pipe trims for Exposed cover
29 cover sealing rings for Exposed
30 cover fixing screw for Exposed
0961137-31 %’ x ‘4’ BSP shower outlet
for Exposed
32 %I’ BSP x 22mm compression elbows
for Exposed
15 back plate for clutch assembly
- flushing
17 ‘& cartridges
17a ‘0’ rings for cartridges
Spares: Please state description and part number when ordering.
General Notes
Trevi Boost is designed to be
installed on normal UK tank fed
hot supply and mains fed cold
supply. The pressure of the cold
water is used to boost the
pressure of the blended water
above that of the hot supply.
This is done using the Venturi
principle as described in section
on Operation.
Both modefs have been
manufactured to be fitted in a
variety of instalfation
configurations to suit the
shower room design, (see
installation section item 1).
Connections on the all brass
mixer body are % BSP and are
marked ‘hot in‘, ‘cold in‘, and
‘mixed out‘. There are two
mixed water outlets, one of
which must be plugged with the
blanking plug supplied, (22).
The supply pipework should be
15mm copper on the cold side
and 22mm copper on the hot
side. A more stable showering
temperature will be achieved if
the hot supply pipe is taken
The Trevi Boost is supplied with
its own shower kit. (Handspray
with flexible hose or fixed head).
These are sized for optimum
.performance and should not be
replaced with alternatives. If an
from a direct cylinder
alternative shower kit of higher
or lower resistance is used the
Supplied with the exposed
performance of Trevi Boost wifl
be affected and a satisfactory
shower mixer are two 3/” BSP
mixed showering temperature
x 22mm compression elbows
(32) for connectinghot and cold may not be achieved. In the
event of the shower head
supplies when concealed in the
becoming partially blocked (for
wall. If the mixer is to be
example with lime scale) or the
installed with surface mounted
shower hose becoming kinked
pipework appropriate pipe
the boosting performance and
fittings are used (not supplied).
showering temperature will be
The % x ‘4’ BSP shower outlet
markedly reduced. Clean the
(31) for the exposed model is
shower heads regularly. Only
connected to the bottom mixed
use genuine Trevi spare parts if
water connection for attaching
the shower hose and hand spray. replacements are required.
Operating Conditions
Trevi Boost is designed to be
installed on traditional UK
vented systems where the hot
cylinder is fed from a cold
storage cistern. It is intended
to be installed where the
storage cistern is on the same
floor as the shower room or in
the roof space immediately
above the shower room (see
Fig. 5). The cold water
pressure must be 1.5 bar
minimum and 3.0 bar
maximum. If the cold water
pressure is between 1.5 and
2.0 bar the Trevi Boost will
give satisfactory results if the
hot water pressure and
temperature are within the
shaded area of Fig.3. For cold
pressures between 2.0 - 3.0
bar, the hot water conditions
defined in Fig. 4 will apply.
If direct mains cold water
pressure is greater than 3.0
bar, a pressure reducing valve
must be fitted. If input
conditions are minimal, (i.e. on
the diagonal line on Figs 3 or
4) then mixed shower
temperature may only read
40°C. (See Installers Guide for
further information).
Hot water requirement when cold pressure is 1.5 - 2.0 bar
hot water head
Fig. 3
Hot water requirement when cold pressure is 2.0 - 3.0 bar
Fig. 4
hot water head
hose must be restrained to ensure
handspray cannot come within 20mm
of spill-over level of bath or shower tray
3m mdx
50cm max
- -I - - 5cm max
hot supply /
must be 22mm
Im min
must be
first point
rf draw oft
hot water
’ storage
single check valve
%” or 22mm
hot supply
single check valve
%” or 15mm
cold supply
‘... hot supply to
other appliances
old mains
Fig. 5
Principle of Operation
The hot and cold inlet supplies
are controlled by twin ceramic
disc cartridges (17). To operate
the valve, turn the volume
control handle (23)
anti-clockwise through 180”.
This admits hot and cold water
into the booster element which
is also a separate removable
The booster element increases
the pressure of the blended
water using the Venturi
principle, (See Fig.6).
Trevi Boost is designed to give a
reasonably stable outlet
temperature even though the
cold inlet pressure may vary as
other fittings in the house are
being used. However, to provide
complete protection in the event
of a cold water failure, it
incorporates a thermal
shutdown device. This device
uses a thermal element which
reacts to over-temperature
water, pushing a valve on to the
seat at the bottom of the
booster cartridge, (see Fig. 6).
In the event of a cold water
failure this valve element
reduces the output flow of Trevi
Boost to a trickle if the water
exceeds 45’: “C. The actual
temperature at which the mixed
flow is cut off will vary from
valve to valve but will usually
occur in the temperature range
45 - 48°C. The flow is not
completely stopped since to do
so may confuse the user into
thinking the valve is turned off
when in reality it would reset as
soon as the water inside it had
cooled. Trevi Boost is a little
sensitive to the height of the
flexible spray head and a slight
temperature rise may be
noticed as the spray head is
hot water inlet
(head from
-0.5m to 3.0m)
temperature from
55°C minimum
Cold water inlet
(pressure from
1 .Ibar to 3.0bar)
thermal shut down devic :e
(reduces flow to a
trickle if mixed water
t e m p e r a t u r e r?
rises above 45 16 “C
boosted mixed
water outlet
Fig. 6
Byelaws Installation Requirements
As the incorrect installation of
water fittings may result in
contravention of Water Byelaws
requirements the following
AND NOTES (IRN) are intended
as guides to water undertakers
and consumers, installers and
their customers.
The IRN’s relate to the Byelaws
implemented by water
undertakers from 1st January
1989. For further information
see “Water Supply Byelaws
Guide” published by the Water
Research Centre (International
Book No. ISBN 1 870779 02 9)
The following I RN’s apply to
the Trevi Boost fitting.
IRN Nos. 101 * and 109*.
Refer to list included on
separate sheet.
Single check valves must be
installed on both hot and cold
inlets to prevent crossflow. A
22mm single check valve is
essential on the hot side and
ideal on the cold side, however
a 15mm check valve can be
fitted to the cold side as an
alternative. These should be
fitted as close upstream as is
practicable, however it is
essential they be positioned
such that they can be serviced
after installation since an
obstruction, especially in the
hot side will greatly reduce the
showering temperature. It is
recommended that the
pipework upstream of the
check valve be flushed out
before the check valve is fitted.
The following WRC listed check
valves have been tested and
found to be suitable for use
with Trevi Boost.
22m CR Socla 22 BS- 6282
(22mm) Socla CR 3/4’
The restraint ring supplied with
the Trevi shower kit MUST be
fitted such that the shower
head can come no closer than
20mm above spillover level of
the shower tray or bathtub over
which the shower is installed.
mixed out
mixed out
I$ czd mzed
hit czd mzed
Fig. 7 As delivered Installation Configuration A
Fig. 8 Installation Configuration B
SC2CR Flamco DN 22 (22mm)
Reliance Water Control Ltd.
RWC Flowguard SC 75 C CRW
I. Trevi Boost is delivered
ready for installation with the
volume control on the left and
the temperature control on the
(See configuration A - Fig. 7).
Trevi Boost can also be installed
in a vertical position as illustrated
Conex Sanbra Ltd.
CR Alsta Saeflo A 30 (22mm).
Installation (continued)
Changing the Valve Orientation
2. If configuration B - Fig. 8 is
required, proceed as follows.
ht hand side
2.1 Remove the cap (7) and
undo the screw (8). Pull off the
temperature control handle
(241, the shroud (9) and the
shroud spacer washers (19).
2.2 Unscrew the temperature
handle carrier (20) and prise
off the temperature handle stop
(21) by inserting a screwdriver
in the slots provided.
outlet to shower
2.3 Place the Trevi Boost body
in the orientation required and
refit the temperature handle
stop (21) so that the large stop
step is to the right hand side
and the appropriate
screwdriver recess is at the
top. Ensure the temperature
handle stop (21) is pushed
fully on to the hex, (see Fig. 9).
2.4 Refit the temperature
handle carrier (20) by screwing
fully clockwise. Replace shroud
spacer washers (19) and
shroud (9) and push fully
2.5 Place temperature control
handle (24) on the handle
carrier (20) with the black
button (Fig, 12) approximately
to the top and push fully home.
Withdraw handle again
carefully by about 6mm or
7mm until it is only just free of
the splines and able to rotate.
Hold this distance from the
body, rotate carefully clockwise
until the handle is felt to touch
the slop. Push temperature
handle (e4) fully home and
tighten screw for temperature
Fig. 9
2 0 ’
.i p 4 5 - 6 5
wall surface
mounting template/
plaster guard (25)
1 minimum
Fig. 10
detail showing ptastea . guard use
control handle (8).
2.6 Rotate handle clockwise
and then anti-clockwise again
and check that handle stops
against the stop.
Built-In installation
3. The Trevi Boost built-in
model is designed to be
recessed into the wall and the
depth of recess should be
measured from the finished
wall surface.
An allowance for tiling etc.
must be made. There is an
adjustment of 20mm in the
installation depth - minimum to
45mm maximum 65mm from
finished wall surface to the
centre line of the connections.
The maximum/minimum
depths are indicated on the
mounting template / plaster
guard (25) supplied.
4. Chase out wall for mixer
body and pipework. Locate
pjpework to suit connections
on the mixer body and flush
out thoroughly to remove
debris, (see item 13).
5. Screw blanking plug (22)
into the unused mixed water
connection on the mixer body
using PTFE tape.
6. With mounting template /
plaster guard (25) attached to
the mixer body, locate the body
in the wall and connect
pipework using appropriate
pipe fittings and PTFE tape,
Inlets and outiets are clearly
marked on the mounting
template / plaster guard (25).
Do not make any soldered
joints near the mixer as this
could damage the cartridges.
7. Screw the mixer body to the
wall using fixing lugs as shown
in Fig. 10. The mixer must be
square with the finished wall
surface. Ensure pipework is
rigidly secured to wall.
6. Remove plaster guard (25).
Exposed Installation
9. If concealed pipework is to
be installed, fit the two 314”
BSP x 22mm compression
elbows, using PTFE tape, to the
hot and cold connections on
the mixer body (Fig. 11). The
removal of coupling nuts on
the elbows will facilitate the
operation otherwise the nuts
will foul each other.
Connections for surface
mounted pipework are shown
in Fig. 11 and again PTFE tape
should be used. Do not make
soldered joint near the mixer as
this could damage the cartridge.
10. Fit the %’ x ‘h” BSP shower
outlet (31) in the bottom mixed
water connection. Fit the
blanking plug (22) in the top
mixed water connection. PTFE
tape should be used with both
items. See also Fig. 11.
11. For a concealed pipework
installation chase out the wall
for supply pipework and the
two % BSP x 22mm
compression elbows which will
project beyond the back of the
mixer (Fig. 12). Locate
pipework and flush out
thoroughly to remove debris.
Connect supply pipework to the
two compression elbows and
pack out the mixer behind, if
necessary, so that the back will
be level with the finished tiled
surface. Complete plastering
and tiling and screw the mixer
to the wall using fixing lugs
(Fig. 12).
12: For a surface mounted
installation screw the mixer to
the wall using fixing lugs.
Locate pipework (Figs. 7 and
8), flush out thoroughly to
remove debris. Connect supply
pipework to the mixer and
ensure that it is rigidly secured
to the wall. Fit plastic pipe
trims for cover (28a) as
connectlon for
surface mounted
Figs. 11 & 12 illustratad in
installation configuration B
Flushing Operation
.l3. Before operating the fitting
it is essential to flush the
pipework to prevent debris
from the plumbing operation
blocking the filter and even the
booster element see Fig. 13 and
14.. To do this proceed as
follows:Turn the volume control handle
fully clockwise to ensure both
cartridges are closed. Pull off
handle (23) and shroud (9).
Loosen screw and remove
handle carrier (10).
Remove clutch cover fixing
screws (12) and pull off clutch
cover (11). Pull out clutch drive
shaft (13) and loosen cone
‘emove cold cartri
%nd drain tube (no
3eplace cold cartr
screws (14a) to release clutch
gears (14). Lift off both clutch
gears (14) and lift off clutch
backplate (J 5).
14. Remove cold cartridge by
unscrewing anti-clockwise and
insert in its place the flushing
outlet (16). Attach a drain tube.
Flush cold system and replace
cold cartridge. Repeat operation
for hot cartridge and flush hot
system. Replace hot cartridge
and ensure both are set in the
‘off’ position.
15. Replace clutch backplate (15)
and both clutch gears (14) with
the flat side facing downwards
and secure with cone screws
(14a). Replace clutch drive
shaft (13) and clutch cover
(11) and secure with screws
(12). Replace shroud (9),
volume control handle carrier
(10) and volume control handle
(23). Turn volume control
handle (23) clockwise through
360” to synchronise the hot
and cold cartridges. The
volume control handle
incorporates a slipping clutch
to prevent damage in the event
of over tightening.
16. Ensure volume control is
turned fully to the off position.
Turn on water supplies and
check for leaks.
flushing outlet (16)
and flush supply pipe.
peat on hot cartridge
Fig. 13 removal of gearbox assembly
Fig. 14
Figs. 13 81 14 illustrated in
installation configuration B - See Fig. 6
flushing drain
Safety for the user
Trevi Boost is not
thermostatically controlled and
outlet temperature depends on
the position of the handle, hot
and cold inlet temperatures and
Before using the shower check
that the temperature of the
mixed water is satisfactory.
Young children, the elderly and
infirm should be supervised
when using a shower.
tdfully on. It is better to
operate the Trevi Boost in the
fully on position since the set
temperature may vary as the
flow control is adjusted.
The temperature control handle
is marked from 1 to 5 - .
position 5 being the hottest.
NOTE: Cartridges are supplied
in sets and both cartridges
should be changed at the same
time. They both operate in the
same direction therefore they
can be fitted to either side.
handspray, proceed as
indicated in the cleaning
instructions supplied with
shower head. If this does not
improve the situation the Trevi
Boost cartridge should be
removed and the filter screen
cleaned. To do this, proceed as
follows:Unscrew handle (24) and
remove shroud (9) and shroud
spacer washers (19). Unscrew
cartridge and examine filter
screen. If blocked, clean and
replace in body.
Ceramic disc cartridges control
the flow of hot and cold water.
Turn the volume control handle
through 180” to move from off
Ceramic disc cartridges
The unique ceramic disc hot
and cold cartridges contain
ultra smooth ceramic discs.
They are so hard that they
always remain sealed together
polishing one another in use,
and sand, sediment or other
water-borne matter cannot get
between them or damage them.
Even the hardest water has no
effect and this means that the
Trevi Boost shower mixer
should give many years of
efficient, trouble-free service
without the drip and liming-up
problems associated with
traditional shower valves.
However, in the unlikely event
of a failure or any problem
simply exchange the cartridges.
To Remove Hot and Cold
Shut off water supply and turn
volume control handle to the
‘off’ position.
Refer to section ‘Flushing
operation’ for details on how
to remove hot and cold
Trevi Boost Cartridge
If the flow performance of Trevi
Boost has become impaired it
is possible the shower head
may have become blocked with
limescale or plumbing debris
may have become lodged on
the filter screen on the booster
Shower Handspray
The shower head must be
cleaned at frequent intervals
especially in hard water areas.
The construction of the
handspray facilitates this.
Adjust temperature handle to
position 1 (full cold setting).
Turn on flow control. Rub the
flexible spray plate nozzles with
the fingers, This enables any
limescale deposit to become
detached, and ejected by the
pressure of the spray. If this
does not completely clean the
No abrasive powders,
detergents or polishes should
be used for cleaning plated,
white or colour finished
bathroom fittings. Cleansers
containing alcohol and other
organic solvents or corrosive
chemicals should not b,e used.
Bleach and denture cleansers
can damage plated or coated
finish brassware. The finish
should be maintained by
wiping with a clean, damp
cloth, then polishing with a
clean, soft, dry duster.
Spare components and
replacement cartridges are
available from Trevi Showers
If you have any difficulty in
obtaining spares locally, please
contact Trevi Showers, PO Box
60, National Avenue,
Kingston upon Hull, HU5 4JE.
Telephone: (01482) 470788.
Telex: 592113.
Telefax: (0148%) 445886.
Trevi Showers pursues a policy
of continuing improvement in
design and performance of its
products. The right is,
therefore, reserved to vary
specification without notice.
Trevi is a registered trade mark.
Trevi Showers is a division of
Ideal-Standard Limited.
Trevi Showers,
The Bathroom Works,
National Avenue,
Kingston upon Hull.
HU5 4HS, England.
Telephone: (01482) 470788.
Telex: 592113.
Any information reproduced
from the Water Research
Centre - “Water Fittings and
Materials Directory” is with the
kind permission of the WRc
Water Byelaws Advisory
. Trevi Boost
Installers Guide To A Better Understanding
Trevi Boost is designed to be installed to provide a good shower where
otherwise a normal plumbed-in shower would be pear or even impossible. i.e.
where the available hot’water head is very low’br even siighttynegative. It can
also ba installed where the availabli hot head is better than minimal in 7wtrich
case the performance will be even better.
Trevi boost uses the energy from the mains cold water to boost the mixed
pressure by mixing the two streams in a special pressure boosting venturi
mechanism. Only the energy contained in-the-c&d yater consumed is
available for this process and it is essential therefore that the whole system,
particularly the hot plumbing is installed to give minimum pressure losses.
\- - - d-
300cm max
hose must be restrained to ensure
handspray cannot come within 20mm
of spill-over Ieve of bath or shower tray
1OOc.m min
single check valve
W or 22mm
hot supply
single check valve
; 1%” or 15mm
cold supply
Supply Conditions
When the input conditions are at the minimum levels specified in the
following charts (Figs 1 & 2) the performance of the valve will also be on
the minimum.
Fig. 1
Hot water requirement when cold pressure is 1.5 - 2.0 bar
hot water head
Hot water requirement when cold pressure is 2.0 - 3.0 bar
Fig. 2
1 .o
hot water head
Thus if a Trevi Boost is installed under the following conditions:
Hot water head
Hot water temperature
Cold water flow pressure
Then the showering conditions would be:
Maximum showering temperature
Shower flow rate
= 65°C
= 40.5%
= 5.3/itres/mhu t e
This assumes the installation has been carried out in accordance with good
plumbing practice and that the Trevi Boost installation instructions have
been carefully followed.
Performance Expectations
Figs 3 and 4 show the mixed showering temperature and mixed water flow
rate to be expected under any particular set of installation conditions.
TREVI BOOST - Maximum Mixed Temperature at Various Hot Water Heads
Cold water flow pressure 1.5 BAR
Hot Water Temperature
Note: Maximum temperatures are approximate and may vary a little depending on installation conditions
Fig. 3
TREVl BOOST - Flow Rates at 40%
Hot Water Temperature
Note: Flow rates given are approximate and may vary a little depending on installation conditions
Fig. 4
If difficulties are experienced in reaching these levels of performance there
may be several causes. See items 1 - 6 on the following paGes
1 There may be a restriction in the hot supply pipes.
Since to boost the shower pressure comes only from the cold
water consumed, any restriction in the flow of hot water will upset the ratio
of Hot and Cold and thus reduce the mixed water temperature. If difficulties
are being experienced the flow rate through the hot pipework should be
checked as follows.
Turn off hot supply and remove hot cartridge. Replace with the flushing
outlet (Part No.096292700) Item No. 16.
Turn on hot supply and measure flow rate in litres per minute from the
nozzle. If the flow rate does not match that shown on Fig. 5 then a
restriction must exist in the hot plumbing and the following points should be
l-lot flow rate through %” flushing outlet
Fig. 5
3 metres
Height from cistern water surface to centre of Trevi Boost valve body
The hot side of the system must be plumbed in 22mm pipe with as
few bends as possible. If 15mm is used even for a short length of the
hot supply, the temperature of the mixed water will be reduced.
The check valve on the hot side must be 22mm or size 3/4.
The check valve may have become partially blocked due to limescale or
plumbing installation debris, If this happens the effective head of the
hot supply will be reduced and a lower mixed water temperature will
NB The check valve must be sited in a position where it can be
serviced after installation.
If the hot supply is conducted above the ceiling care must be taken to
ensure the pipe is properly vented since air locking which can result
will restrict the hot flow. This will reduce the mixed water temperature.
There must be no other obstructions eg: PTFE tape brigAging the end of
a connection spigot.
Where hot water head is less than 0.5 m, long pipe runs and many
bends must be avoided.
The stop valve/or valves between the cold cistern and hot storage
cistern may only be partially open. Ensure all stop valves are fully
2 The mixed water outlet may be partially obstructed
The Trevi Boost’s performance is dependant on a carefully controlled back
pressure. For this reason a special hose (where a flexible shower is
specified) and spray head are supplied with the valve. If Trevi Boost is
failing to give the temperature indicated on Fig 3 then there may be an
obstruction downstream of the boost cartridge. One of the following
reasons may be the cause:
The shower head may have become partially limed up. b clean the
shower head, turn the temperature control knob to full cold and open the
flow control fully Rub the rubber spray nozzles on the spray plate with the
fingers - this should dislodge any limescale which may have started to
build up. If this fails to clear the spray holes completely it will be necessary
to dismantle the spray head and clean the rubber spray plate separately
Reassemble and check the mixed temperature.
If the handspray has become damaged in any way and requires to be
replaced it is essential to the correct operation of the Trevi Boost that it be
replaced with a handspray of the same resistance. This handspray has
Part No.035566200
If the flexible shower hose has at any stage been partially flattened or
kinked the inner skin of the hose may have become detached and could
be causing a restriction. Fit a replacement hose of the same type and try
The performance of Trevi Boost is dependant on the Correct hose
being fitted. Replacement hose Part No.0991 02463
Installation debris may have become lodged in the Trevi Boost
cartridge around the temperature safety cut-out and may be causing’
a restriction. With flow control turned off remove the Trevi Boost
cartridge and inspect. If obstructed clean carefully and replace.
3 The temperature control handle may be wrongly positioned on the
If the handle has been removed during installation it may not have been
replaced correctly and may be rotating against the stop before the cartridge
has been adjusted through its full travel. This will prevent the mixed
showering temperature reaching its design maximum. Refit handle in
accordance with the installation instructions.
4 The temperature handle stop may not be fully seated on the body of
the booster cartridge
When the temperature stop is pushed on to the hex at the end of the
booster cartridge it must be pushed fully home otherv4se it will prevent the
full travel of the temperature control mechanism. This could prevent the
Trevi Boost cartridge being adjusted to the full hot setting.
5 There may be a restHction in the cold supply
If there is a restriction in the cold supply preventing the full line pressure of
cold water reaching the Trevi Boost the flow rate and temperature may not
reach the performance levels indicated in Figs 1 & 2. lb verify the cold flow
pressure do the following test.
Set the handspray to the normal showering height and check that the
handspray is free from debris and limescale.
Adjust the temperature control knob to full cold.
Turn flow control knob to full on.
Measure flow rate in litresiminute using a graduated bucket and
Read off flow pressure on Fig 6 against this flow rate.
TREVI BOOST - Flow Rate at Full Cold
Measured Through Shower Hose and Handspray at Normal Showering Height
Fig. 6
cold pressure
(N.B. If the flow rate is less than 12 litres/minute then the flow pressure is
less than the required 1.5 bar).
6 The stored hot temperature may be less than the required minimum
For a shower of 40°C the following stored hot water temperature is required.
For Cold Pressure Between 1.5 and 2.0 Bar
Head (hot water)
-0.5m to O.Om
O.Om to 0.5m
0.5m to I.Om
I.Om and above
For Cold Pressure Above 2.0 Bar
Hot Temperature
Head (hot water)
Hot Temperature
-0.5m to O.Om
O.Om to 0.5m
0.5m and over
It is recommended, in the interests of safety, that hot stored water
temperatures above 65°C should only be used where the hot water head is
lrevi Boost Mixer Only Cartridge
The highest mixed water temperature achievable is shown on Fig 3 and the
previous explanation covers all the likely installation problems which may
have combined to reduce this figure. If, however, a higher showering
temperature is required it will be necessary to increase either the hot water
temperature or the hot water head. In some cases both may have to be
If these have already been optimised it is possible to increase the mixed
water temperature by Replacing the standard Trevi Boost cartridge with a
“Trevi Boost mixer only cartridge”. This is similar to the standard Trevi
Boost cartridge but without the over temperature cut-out.
With this mixer only cartridge fitted the output temperature is still
reasonably stable to changes in cold water pressure down to 0.5 bar at hot
water heads up to 1.5 meters but, if the cold water fails completely the
full hot water temoerature would be delivered. This of course is no
worse than a normal mechanical mixing valve however if making this
change to an installation the householder must be advised. It should not
be necessary to use this solution at hot water heads above 1.5 meters
since the performance should already be good.
Please contact Trevi Showers on 01482 470788 if a mixer only cartridge is
Trevi Showers pvrsues a policy of
continuing improvement in design and
performance of its products. The right
is, therefore, reserved to vary
specification without notice.
Trevi is a registered trade mark.
Trevi Showers is a division of
Ideal-Standard Limited.
Trevi Showers,
The Bathroom Works,
National Avenue,
Kingston upon Hull,
HU5 4HS, England.
Telephone : 01482 470788.
Telefax : 01482 592113.
Boost Testing Procedure2: Page 1 of 2
Testing Procedure: Trevi Boost
Note: the tests are carried out in a sequence intended to “fast track” the problems, but of
course the sequence can be varied as preferred!
Begin by recording the temperatures of the Hot and Cold supplies, check that they do not vary by
running both for at least 5 minutes, ensure that the flow doesn’t vary during this time.
Is the temperature handle fitted in the correct position so that it has the full amount of travel?
Correct if wrongly positioned before continuing.
Measure the output temperature at the Shower head in it’s normal position. Is it as it should be?
Examine the shower head, is it the correct type? Is the pattern from it good, or is the flow pattern
poor? Carry out the normal cleaning operation for the shower head by turning the temperature
control knob to position 1 (maximum cold setting) and scratching the spray plate nozzles to
dislodge any particles. If the nozzles do not stick out fully from the spray plate , then the
diaphragm has shrunk: Replace the insert
Remove the Shower head and see if the temperature rises, if it is now at the correct level, replace
the shower head, if not do the same test by removing the hose and replacing if necessary.
If there is still a problem take off the Handles and front plate from the Trevi Boost, replace the
volume control handle, remove the Temperature handle carrier and the handle stop , pack the
irregular cavity in the wall with plastic bags to prevent the loss of parts, and leakage of water into
the wall cavity and then remove the boost cartridge and examine it. Are the filters clear? Is the
temperature limiter off centre in it’s housing? (this can reduce the output flow and temperature)
Open the volume control fully and flush out the mixer.
Undo the two screws on the gearbox and remove the cover and spindle, operate the valves
individually and check that they are free moving, and that the clutches work. Replace any
defective parts.
If a cartridge flushing nozzle is available then the clutches, backplate and each flow cartridge
should be removed in turn and the nozzle used to flush out the body.
Refit the gearbox and screws, and refit the volume control knob.
10. If a test Nozzle is available fit it into the mixer port and open turn on the Volume control to test the
available hot head.
11. Consult the test charts , Test the Incoming cold Supply Pressure, and the Hot head. Record the
results, test also the flow rates through the shower head at maximum hot and cold settings,
compare the results with the charts.
12. If there is a discrepancy with the pressures and flows obtained, first examine the Check valves for
obstructions and clear them, then do the tests again.
13. If the blockage hasn’t cleared, it will be necessary to test the body casting for internal
obstructions: remove the gearbox and clutches etc : insert a 5 pence coin into the shower head end
of the hose to seal it, replace the boost cartridge to block the port, turn off the supply and remove
each inlet valve in turn, fit the flushing nozzle in place of the valve, restore the respective supply,
test and record the flow from the open port.
14. Next replace the back plate for the gearbox and the clutch wheels, but do not refit the drive
spindle and gearbox cover. Remove the Boost cartridge, open each valve in turn and test the flow
coming out of the boost port. If there is a difference in the readings from this port and the valve
ports, then the casting is blocked. (Do not forget to retrieve your 5p piece after this test!
15. Replace the mixer body if a blockage is evident, otherwise rebuild the unit.
Page 1 of 2
Boost Testing Procedure2: Page 2 of 2
16. Consult your collected readings, if the cold pressure and hot head are outside the minimum
parameters, then inform the consumer/installer and make for the exits!
17. If the mains pressure is below 1.5 bar, has the plumber turned the main stop cock to the house
down in an attempt to raise the temperature from the Boost?
I f the temperature is till low but the pressure is above 1.5 bar, and the hot head is very low, then a
P.R.V. will be needed to bring the situation under control: you can prove the this will work to the
consumer be removing the geabox cover and spindle and operating the volume control valves
independently (ie opening the hot valve fully and the cold valve part way)
18. Ensure that the hot supply is both hot enough and constant, and check that the storage cylinder is
of adequate capacity (75 gallons as against the usual 40) does the unit run cool after a time?
Enquire about airlocking (does the unit make spluttering noises before the warm water arrives?
19. In the rare event of the unit producing hot water that is too hot, has it got a positive head and
someone has removed the temperature limiter to “improve the supplies?”
20. Have the pipes been fitted in reverse?
21. Have both supplies been fitted either to a tank feed, or both to mains via say a combi?
Consumers frequently misunderstand the functionality of the Trevi Boost and can’t see that since cold
water and hot wlll always be present, the extremes of the temperature range cannot be achieved.
The number of units that are fitted with incorrect Shower heads and Hoses is surprising, and very few
consumers actually clean the shower heads, which are often completely limed up when you visit.
Page 2 of 2
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