Powers 420U User Manual

Shown above: Model 420-RB-E-S-S-0-0

tronic faucets), checkstops (highly recommended) or other
accessories common to Powers’ cabinet supply offering.

DESCRIPTION

Hydroguard Series 420 Under-the-Counter thermostatic tem­pering valves are designed for all applications where the tem­perature of generated hot water must be controlled for safe,
economic use. A powerful liquid-filled motor quickly senses
and compensates for temperature fluctuations induced by
water temperature and pressure changes in the supply line.

Rugged construction features cast brass body and corrosion­resistant internal components for years of dependable, trou­ble-free service. Screwdriver stem makes temperature adjust­ment quick and easy.

For restricted access control, the Series 420 valve can be
housed in a stainless-steel or white baked enamel steel cabi­net and can be packaged with solenoid valve(s) (for ESP elec-

SPECIFICATIONS

Valve Construction:

Under-the-Counter thermostatic mixing valve, with heavy cast bronze body and brass stem with screwdriver adjust­ment.

Capacity..............................................Standard ................................................6 gpm [22.7 L/min]* (±0.5 gpm [1.9 L/min])

High ........................................................8 gpm [30.3 L/min]* (±0.5 gpm [1.9 L/min])

Low......................................................3.5 gpm [13.2 L/min]* (±0.5 gpm [1.9 L/min])

Maximum Hot Water Supply Temperature ......................................................................................................190°F [88°C]

Minimum Hot Water Supply Temperature

(not applicable to low temperature hot water valve) ....25°F [14°C] above set point

Maximum Operating Pressure ................................................................................................................125 psig [862 kPa]

Temperature Ranges........................................................................................................Standard......65–115°F [18–46°C]

High ..........120–175°F [49–79°C]

Low ..................40–90°F [4–32°C]

Maximum Static Pressure........................................................................................................................125 psig [862 kPa]

Minimum Flow and Pressure Differential: Minimum Flow

Minimum Pressure Differential

Standard Capacity ............................................................2.5 gpm [9.5 L/min]......................................10 psi [69 kPa]

High Capacity ....................................................................4.5 gpm [17 L/min] ....................................15 psi [103 kPa]

Low Capacity......................................................................1.0 gpm [3.8 L/min]........................................5 psi [34 kPa]

Shipping Weight................................................................................................................................................5 lbs. [2.3 kg]

The Hydroguard Series 420 Under-the-Counter standard and high capacity valves meet the above operating conditions
as stated in ASSE 1017 (45 psi pressure differential, hot water supply between 140°–180°F [60–82°C], cold water supply
less than 70°F [21°C]).

If your operating conditions vary from those stated in the standard, performance may vary as well. Consult your local
sales representative or a Powers factory engineer to discuss your specific application. All Powers Under-the-Counter
thermostatic mixing valves perform to the requirements of standards ASSE 1017 and CSA B125.

* At 45 psi differential [310 kPa], with hot water supply between 140°–180°F [60–82°C].

TECHNICAL INSTRUCTIONS

Hydroguard Series 420

Under-the-Counter Thermostatic Tempering Valve

OPERATION

Hot and cold water supplies enter the 420
Hydroguard through their respective inlet ports. Both
supplies mix in the chamber containing the valve
assembly. The resulting mixture flows across the
thermostatic motor, and the motor positions the
valve assembly to maintain the desired delivery
water temperature.

Delivery water temperature can be varied by turning
the adjustment stem. Turning the stem counterclock­wise raises the temperature, and turning the stem
clockwise lowers the temperature. WARNING: A
valve without checkstops, left in the open position,
even with a downstream shutoff valve used, does
not prevent crossflow.

TI420U

(Operation continued on page 3)

2

3

OPERATION (continued from p. 1)

If the temperature of the mixture is higher than the
temperature setting, the thermostatic motor actuates
the valve assembly toward the hot water seat. Hot
water flow decreases and cold water flow increases.
Thus the mixture temperature is brought down to the
desired temperature. The reverse occurs when the
mixture temperature is lower than the temperature
setting.

A change in water temperature or pressure of either
hot or cold water supply will cause the thermostatic
motor to reposition the valve assembly to maintain
the desired delivery temperature.

420 Hydroguard supplies tempered water to
self-closing and/or solenoid valves, Powers rec­ommends use of a shock absorber (Powers Part
No. 460-353) on the discharge line. This protects
the 420 Hydroguard thermostatic motor from
damage.

3. Locate the valve as close as possible to outlet
fixture to avoid waste of energy and water
except in applications where the valve is used as
a primary mixing valve to supply an entire build­ing.

4. Correct valve sizing affects valve and system
performance; under- or over-sizing of the mixing
valve(s) can cause poor operation and possibly
injury. Refer to Sizing Information on page 6.

Adherence to these guidelines and recommenda­tions promotes safe product use and ensures prop­er valve performance.

1. Thermostatic water mixing valves are control
devices which must be cleaned and maintained
on a regular basis. Powers specifies periodic
maintenance at least once a year or immediate­ly after any changes are made to the plumbing
system. Although annual cleaning is recom­mended, frequency of cleaning depends on
quality of local water conditions. Refer to
Preventive Maintenance on page 4 for recom­mended cleaning procedure.

2. Quick closing valves may cause damage to the
mixing valve by creating shock waves. When the

SAFETY & PERFORMANCE GUIDELINES

Note: All Powers products are subject to the Terms &
Conditions of Sale and Warranty Information, found in the
current Powers CPL Price List.