Armstrong 425 Instruction Manual

Model No. q Model 425
q Model 425D
Serial No. :
Ship Date :
Model 425
Installation and Maintenance
Water Temperature Controls
Groups of Fixtures - Thermostatic
Keep this manual with installation for
future reference.
Armstrong International
221 Armstrong Blvd., Three Rivers, Michigan, 49093 - USA
armstronginternational.com/brain

2
Introduction.............................................................. 3
Specications .......................................................... 5
General Advisory ..................................................... 5
Safety ...................................................................... 6
Pack Contents ......................................................... 7
Schematic Piping..................................................... 8
Installation ............................................................... 9
General................................................................ 9
Installation Requirements.................................... 9
Tools Required .................................................... 9
Installation Procedure........................................ 10
Commissioning...................................................... 12
Operation............................................................... 13
Servicing & Maintenance....................................... 14
Spare Parts............................................................ 17
Troubleshooting..................................................... 20
Notes ..................................................................... 22
Limited Warranty and Remedy .............................. 24
Contents

3
Thermostatic Mixing Valves (LPM and BAR)
Model
425
Pressure Drop (BAR) Min.
Flow C
V
0.30.7 1.01.4 1.72.1 2.42.8 3.13.4
LPM 56.8 83.3 102.2 117.3 132.5 143.8155.2166.6174.1185.57.6 6.9
Thermostatic Mixing Valves (GPM and PSI)
Model
425
Pressure Drop (PSI) Min.
Flow C
V
5101520253035404550
GPM152227313538414446492.0 6.9
Thermostatic
Model 425
The model 425 Thermostatic Mixing Valve is for institutional
group fixture water temperature control. Compact design with
top and/or bottom blended water outlet makes Model 425 ideal
for recessed enclosure, plumbing chase and utility/mechanical
room installation.
Powerful internal mechanism and stainless steel operating
mechanism resist mineral deposition.
Capable of close temperature control at diverse flow rates
between 2 gpm (7.5 lpm) and 49 gpm (185 lpm). Able to blend
to within 5°F (2°C) of either inlet supply due to “low seepage”
across internal proportioning mechanism.
Operational Specifications
• Dual thermostatic elements provide redundancy in the
event of individual thermostat failure.
• Typical outlet temperature control +/-2°F
• Adjustable maximum temperature limit stop
• Adjustable single temperature lockout
• Thermal shutdown mode upon inlet supply failure
Technical Specifications
• 1-1/4” NPT inlets and 1-1/4” outlet
• Chrome plated brass/stainless steel
• Lead Free compliant
• Operating pressures
Maximum: 150 psi (10 bar)
Minimum: 10 psi (.7 bar)
• Integral inlet check valves and strainers
• ASSE 1017 and CSA B125 certified
• Shipping weight 18 lbs (8.1 kg)
For a submittal drawing, refer to D73767.
Designs, materials, weights and performance ratings
are
approximate and subject to change without notice.Visit
armstronginternational.com for up-to-date information.
Armstrong
Hot Water Group, 221 Armstrong Blvd., Three Rivers, MI 49093 – USA
Phone: [phone], Fax: [phone]
Water Temperature Control - Groups of Fixtures
6.61
(168.0)
3.92
(99.5)
7.63
(193.7)
2.45
(62.2)
7.83
(199.0)

4
Thermostatic
Model 425D
A derivative of the standard Model 425 Thermostatic Mixing
Valve for institutional group fixture control. Compact design with
top and/or bottom blended water outlet makes Model 425 ideal
for recessed enclosure, plumbing chase and utility/mechanical
room installation.
Factory supplied pre-plumbed and pressure-tested Model
425D is supplied as standard with inlet check valves, strainers,
unions, isolations valves and outlet thermometer and stop
valve*.
*Model 425D is supplied with top outlet and can be site
reconfigured for bottom outlet applications.
Operational Specifications
• Dual thermostatic elements provide redundancy in the
event of individual thermostat failure.
• Typical outlet temperature control +/-2°F
• Adjustable maximum temperature limit stop
• Adjustable single temperature lockout
• Thermal shutdown mode upon inlet supply failure
Technical Specifications
• 1” NPT inlets and 1” NPT outlet
• Chrome plated brass/polymer construction with self finish
brass and bronze lead free components
• Lead Free compliant
• Operating pressures
Maximum: 150 psi (10 bar)
Minimum: 10 psi (.7 bar)
• Inlet check valves, strainers, unions and isolation valves
• Fitted with outlet thermometer and isolation valve
• ASSE 1017 and CSA B125 certified
• Shipping weight 35 lbs (15.9 kg)
For a submittal drawing, refer to D76002.
Thermostatic Mixing Valves (GPM and PSI)
Model
425D
Pressure Drop (PSI) Min.
Flow C
V
5101520253035404550
GPM152227313538414446492.0 6.9
Designs, materials, weights and performance ratings
are
approximate and subject to change without notice.Visit
armstronginternational.com for up-to-date information.
Armstrong
Hot Water Group, 221 Armstrong Blvd., Three Rivers, MI 49093 – USA
Phone: [phone], Fax: [phone]
Water Temperature Control - Groups of Fixtures
Thermostatic Mixing Valves (LPM and BAR)
Model
425D
Pressure Drop (BAR) Min.
Flow C
V
0.30.7 1.01.4 1.72.1 2.42.8 3.13.4
LPM 56.8 83.3 102.2 117.3 132.5 143.8155.2166.6174.1185.57.6 6.9
9.9
(252)
5.0
(126)
TYP
11.0
(279)
TYP
13.6
(345)

5
Specications
*Model 425 can accept temporary excursions above 185°F (85°C) and maintain control without sustaining
internal damage. (ASSE 1017 certification requires exposure to 200°F (93°C) for a period of 30 minutes).
Prolonged operation of the Mixing Valve at such elevated temperatures is not recommended.
** Normal operating conditions are considered as a differential of approximately 122°F (50°C) between
the hot and cold inlet temperatures, and with differentials of 59°F (15°C) - 95°C (35°C) between the
blend setting and either supply. 59°F (15°C) is the optimum published minimum differential required to
achieve full thermal performance.
Maximum Hot Water Supply Temperature 158°F (70°C) *
Minimum Cold Water Supply Temperature 33°F (1°C) - 77°F (25°C)
Optimum Minimum Inlet to Outlet Temperature Differential 59°F (15°C) **
Optimum Thermostatic Control Range 86°F (30°C) - 122°F (50°C)
Flow Rate at 45 psi 46 gpm (174 lpm)
Minimum Flow Rate 2 gpm (7.5 lpm)
Maximum Inlet Supply Pressure 150 psi (10 bar)
Minimum Inlet Supply Pressure 10 psi (0.7 bar)
General Advisory
This Model 425 Valve has been supplied for this application based upon information provided to Armstrong at the
time the order was placed.
This Model 425 Valve is configured for use in a “dead-leg” piping configuration.
This Model 425 Valve has not been congured for use in a central pumped re-circulation system.
This Model 425 Valve is not designed to deliver tepid water to emergency fixtures.
For further information, please call our technical department 1-269-279-3602 between 08:00 a.m. to
05:00 p.m. EST.

6
Safety
Applicable codes must be followed and supersede any other instructions.
Generally applicable codes in the US include:
• IPC (International Plumbing Code)
Read this manual
Improper installation or operation may cause a ood resulting in property
damage, personal injury, or death. Armstrong strongly recommends that
a qualied installer be used.
Service must be performed by a qualied person.
Improper installation, start-up, operation, maintenance, or service may
void the warranty.
Hot water or metal may cause scald burns. Skin exposure to 140°F water
or metal for only ve seconds may cause a second degree burn.
Icon Legend
If instructions are not followed:
- injury or death and property damage are imminent
- injury or death and property damage are possible
- potential property damage, expensive repairs, and/or voiding
the warranty may result
The function of a Thermostatic Mixing Valve is to deliver water consistently at a pre-designated temperature.
Model 425 Thermostatic Mixing Valves are precision engineered to give continued superior and safe
performance provided:
1. They are installed, commissioned, operated and maintained in accordance with the recommendations
provided and accepted plumbing practices.
2. Periodic attention is given, as necessary, to maintain the product, the accessory fittings and the plumbing
system in good functional order.
In keeping with every other mechanical product, Model Mixing Valves should not be considered as
functionally infallible and, as such will never totally replace the vigilance and attention of facility nursing/
bathing or other institutional supervisory or industrial safety staff.
Provided that they are installed, commissioned, operated and maintained, the risk of product failure and
its associated consequences, if not eliminated, are reduced to the minimum achievable.

7
Pack Contents
X 1 q
X 1 q
X 1 q
X 3 q
X 1 q

8
Hot Water Supply
Water Heater
Rada 425
Mixed Flow
Cold Water Supply
System Layout
Thermometer
Sink
Shower
Check Valve
Isolation Valve
Stop Valve
Flow Direction
Pipeline
Schematic Piping

9
Installation
General
Installation must be carried out in accordance with these instructions, and must be conducted by designated,
qualied and competent personnel.
The installation must comply with all relevant local and state water plumbing codes.
All plumbing components are to be supplied by the installer. Failure to include these components will compromise
the product, system performance and will void the warranty.
Notes:
1. Model 425 is supplied fully performance and pressure tested.
2. Suitable connections for ease of maintenance should be used on the inlet and outlet ports. (Isolation valves
and unions.)
3. The hot and cold water inlet supply pressures must be nominally equal.
4. The inlet supply pipework must be thoroughly ushed before tting the Model 425 valve.
5. The Model 425 can be installed in both rising supplies and falling supplies.
Installation Requirements
1
2
3
4
5
The use of supply strainers will reduce debris entering the Model 425. The recommended gauge for such
strainers is 35 mesh (mesh aperture dimension = 0.5mm).
Inlet pressure tappings which allow measurement of the inlet pressures to the Model 425 under operating
conditions are particularly recommended for in-service testing.
Pipework must be rigidly supported to avoid any strain on the connections.
Inlet and outlet threaded joint connections should be made with PTFE thread sealing tape or liquid sealant.
Do not use oil-based, non-setting joint compounds.
Run water for 1 minute from both hot and cold supplies to eliminate pipe debris. It is essential that supply
pipes are thoroughly ushed through before connection to the Model 425.
3.0 mm
Tools Required
Driling Drill Bit Screw Driver Pencil Adjustable Allen Key Safety
Machine size 6 mm Plus & Minus Spanner size 3mm Glasses

10
Ø 6mm
a. Unscrew the set screw.
b. Remove the Backplate.
a. Use the Backplate to mark the two mounting holes at
the desired height.
b. Drill the holes (6 mm) and t the wall anchors. Screw
the Backplate to the wall.
Caution! Avoid area where underground wirings
or pipelines pass through.
a. Mount the Valve assembly on the Backplate xed on
the wall. Make sure the Valve assembly locks in the
groove.
b. Tighten the set screw.
a. Important! Prior to assembly of the hot and cold
adapters, look inside each one and ensure that there is
a strainer and a white plastic checkvalve. The adapter
with nothing inside is for the outlet.
Thread the coupling nuts onto the Valve assembly
then tighten using an adjustable spanner.
Caution! Use a soft cloth to protect the plating
from damage while tightening the spanner.
Step 1
Step 3
Step 2
Step 4