rada 425-t3 User manual

1
IMPORTANT
Installer: This Manual is the property of the customer
and must be retained with the product for
maintenance and operational purposes.
PRODUCT MANUAL

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INDEX
Page
SAFETY WARNINGS 3
ADVICE 3
INTRODUCTION 4
DESCRIPTION 4
PACK CONTENTS 5
DIMENSIONS 6
SPECIFICATION 7
INSTALLATION 10
COMMISSIONING 13
OPERATION 16
FAULT DIAGNOSIS 17
MAINTENANCE 19
SPARE PARTS 37
CUSTOMER CARE Back Cover
If you experience any difficulty with the installation or operation of your new
mixing valve, then please refer to the Fault Diagnosis section, before
contacting Kohler Mira Limited. Our telephone and fax numbers can be found
on the back cover of this guide.

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SAFETY : WARNINGS
1. It is installed, commissioned, operated and maintained in accordance with the
recommendations given in this Manual.
2. Type 3 valves are only used for applications covered by their approved
designations.
3. Periodic attention is given, as necessary, to maintain the product in good functional
order. Recommended guidelines are given in the MAINTENANCE section.
4. Continued use of this product in conditions outside the specification limits given
in this Manual can present potential risk to users.
The function of this thermostatic mixing valve is to deliver water consistently at a
safe temperature. This requires that:
The use of the word ‘failsafe’ to describe the function of a thermostatic mixing
valve is both incorrect and misleading. In keeping with every other mechanism it
cannot be considered as being functionally infallible.
Provided that the thermostatic mixing valve is installed, commissioned, operated
within the specification limits and maintained according to this Manual, the risk of
malfunction, if not eliminated, is considerably reduced.
Malfunction of thermostatic mixing valves is almost always progressive in nature
and will be detected by the use of proper temperature checking and maintenance
routines.
Certain types of system can result in the thermostatic mixing valve having excessive
‘dead-legs’ of pipework. Others allow an auxiliary cold water supply to be added to the
mixed water from the mixing valve. Such systems can disguise the onset of
thermostatic mixing valve malfunction.
Ultimately, the user or attendant must exercise due diligence to ensure that the delivery
of warm water is at a stable, safe temperature. This is particularly important in such
healthcare procedures as supervised bathing of patients unable to respond immediately
to unsafe temperatures.
ADVICE

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INTRODUCTION
The Rada 425-t3 Thermostatic mixing valve is specified to meet the highest standards
of safety, comfort and economy as demanded by todays users. The Rada 425-t3 is
designed, manufactured and supported in accordance with accredited BS EN ISO
9001:1994 Quality Systems.
This Manual covers all Rada 425-t3 Thermostatic mixing valves manufactured from
May 2001.
The suffix t3 indicates that the valve has been certified for use in UK healthcare
premises as a Type 3 mixing valve under the TMV3 scheme. Where this product is to
be used in such an installation, particular Application, Installation, Commissioning
and Maintenance requirements apply. These are given in the section ‘TYPE 3 VALVES’.
DESCRIPTION
Rada 425-t3 c - Exposed model, surface mounted. Angle inlet checkvalve
elbows rotate to accept rising, falling or rear-fed supplies.
A 1" inlet/outlet thermostatic mixing valve employing the unique 'thermoscopic'
temperature sensor to provide water at safe, accurate temperatures for ablutionary
or process requirements.

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PACK CONTENTS
Tick the appropriate boxes to familiarize yourself with the part names and to confirm
that the parts are included.
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Documentation
1 x Product Manual 
4 x Fixing Screws 
3 x Compression Fittings
4 x Wall Plugs 
1 x 425-t3 Mixing Valve 
1 x Hexagonal Wrench 

3 x Olives 
3 x Compression Nuts 

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All dimensions are nominal and in mm
DIMENSIONS
200 mm
300 mm
56 mm 144 mm
150 mm
73.5 mm
246 mm

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SPECIFICATION
Normal Operating Conditions are considered as:
- inlet dynamic pressures nominally balanced to within 10% of each other during
flow.
- a differential of approximately 50oC between the hot and cold inlet temperatures,
and with differentials of 15-35oC between the blend setting and either supply.
- daily usage of 1-6 hours.
- installation and usage environment not subject to extremes of temperature,
unauthorised tampering or wilful abuse.
Other Applications
For information on other specific applications or suitability, refer to Kohler Mira Ltd, or
Local Agent.
Disinfection
In applications where system chemical disinfection is practised, chlorine can be used
(calculated chlorine concentration of 50 mg/l (ppm) maximum in water, per one hour
dwell time, at service interval frequency). Such procedures must be conducted strictly
in accordance with the information supplied with the disinfectant and with all relevant
Guidelines/Approved Codes of Practice.
If in any doubt as to the suitability of chemical solutions, refer to Kohler Mira Ltd, or
Local Agent.
Pressures and Flow Rates
Recommended Minimum Dynamic Supply Pressure: 0.15 bar (0.2 bar
healthcare).
Recommended Minimum Flow Rate: 8 l/min at mid-blend with equal dynamic
supply pressures.
Recommended Maximum Flow Rate: 200 l/min at mid-blend (which equates
to maximum pressure loss of 3.5 bar).
Maximum Pressure Loss Ratio*: should not exceed 10:1, in favour of either
supply, during flow.
Maximum Static Pressure is 10 bar.
Recommended maximum flow velocity in pipelines is 2 metres/second.
Operating Parameters
For Type 3 valves the supply conditions specified in Type 3 Valves - Application take
precedence over the operating parameters which follow.
For optimum performance, dynamic supply pressures should be nominally
equal.

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Temperatures
Optimum Thermostatic Control Range: 35 - 46oC.
Recommended Minimum Cold Water Temperature: 1oC.
Recommended Maximum Hot Water Temperature: 85oC.
0 1 2345
0
200
150
100
50
250
Pressure Loss - bar
Flow Rate - Litres/Min
Hydraulic Restriction: Flow Rate Pressure Loss Graph
(mixing valve only, equal dynamic supply pressures and mid-blend temperature
setting, rising or falling pressure loss).
Optimum performance is obtained when temperature differentials of 20oC or more
exist between blend and either supply. Blend control accuracy will begin to diminish at
temperature differentials below 12oC.
Blend Temperature Range: between ambient cold and approximately 60oC,
according to hot water supply temperatures.
Thermostatic Control Range: approximately 25-60oC.
Note! If the hot water supply system does not incorporate safety devices (e.g. non self
resetting thermal cut out) to prevent this temperature being exceeded then the use of
a tempering valve may be considered to limit the temperature of the water supplied to
the mixing valve. The output temperature of this tempering valve must be set to a value
not less than 60oC and it must not exceed 85oC if the hot water supplied to it reaches
the maximum possible value which may occur under fault conditions in the hot water
apparatus.
* Pressure Loss Ratio is determined by subtracting the resistance of the outlet
pipework and outlet fittings from the dynamic pressures of the hot and cold
water at the inlets of the mixing valve. This is at its extreme when the mixing
valve is used at its lowest flow-rate and when the maximum inequality occurs in
the pressure of the hot and cold water supplies.

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The Rada 425-t3 mixing valve does not have integral flow control, appropriate provision
must be made for this in the outlet pipework.
This can be in the form of basin/bath tap, stop-cock, mechanical timed-flow controller
or solenoid.
The device chosen must be non-concussive in operation.
Flow Control
Connections
Rada 425-t3 c - inlets and Outlet: 1" BSP female/28 mm compression. Angle inlet
checkvalve elbows rotate to accept rising, falling or rear-fed
supplies.
Standard connections are: hot - left (marked red)
cold - right (marked blue)
outlet - top (can be altered to bottom outlet
if required by repositioning the drain
plug)
This model can operate in any plane, provided hot and cold pipework is connected to
the appropriate inlets (hot - red, cold - blue).

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INSTALLATION
General
Installation must be carried out in accordance with these instructions, and must be
conducted by designated, qualified and competent personnel.
1. Before commencing, ensure that the installation conditions comply with the
information given in SPECIFICATION. For Type 3 valves see also Installation
conditions in TYPE 3 VALVES.
2. Care must be taken during installation to prevent any risk of injury or damage.
3. The mixing valve should be positioned for easy access during use and
maintenance. All routine maintenance procedures can be conducted with the
mixing valve body in place (except for strainer and checkvalve access). For all
models, allow a minimum 80 mm clearance in front of the temperature control to
enable removal of the servicable parts during maintenance.
4. The use of supply-line or zone strainers will reduce the need to remove debris at
each mixing valve point. The recommended maximum mesh aperture dimension
for such strainers is 0.5 mm.
5. Pipework must be rigidly supported.
6. Pipework dead-legs should be kept to a minimum. The mixed water outlet piping
should not exceed 2 m and the overall length from the hot water circuit to the
discharge point should not exceed 5 m.
7. Supply pipework layout should be arranged to minimise the effect of other outlet
usage upon the dynamic pressures at the mixing valve inlets.
8. Inlet and outlet threaded joint connections should be made with PTFE tape or
liquid sealant. Do not use oil-based, non-setting jointing compounds.
9. To eliminate pipe debris it is essential that supply pipes are thoroughly
flushed through before connection to the mixing valve.
Outlet Position/Reversed Inlets
The Rada 425-t3 c mixing valve is supplied with the inlet connections configured
hot - left, cold - right, and top outlet as standard.
Should the existing hot and cold pipework make this configuration inconvenient
then turn the whole valve through 180o (The internal components are not
reversible).
If a bottom outlet position is required, remove the blanking cap from the bottom of
the valve and replace it with the fitting from the top of the valve. Then fit the
blanking cap to the top of the valve.