A.O. Smith AWH-35 Instruction Manual Download

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PHASE MONITOR

Some of the higher capacity models are equipped with Phase Monitor and Compressor Overload modules that interface with the Control

Board. See Table 12 on page 31.

• If all 3 phases of power are present and in sequence, the normally open contacts (Y/Y-OUT) will close when 24 volts is applied

between C and

terminals. The green LED on the Phase Monitor will be energized.

• If the phases are out of sequence, or if one or more phase is dropped when power to the HPWH unit is turned on, the normally

open contacts (Y/Y-OUT) will not close and the control system will lockout. Compresso

, blower and pump operation will be disabled

until the problem is corrected and the control system is reset. The red LED on the Phase Monitor will be energized.

• If a phase is dropped or becomes out of sequence while the HPWH is energized, the Phase Monitor contacts will open immediately

and and the control system will lockout. Compressor, blower and pump operation will be disabled until the problem is corrected and

the control system is reset. The red LED on the Phase Monitor will be energized.

COMPRESSOR OVERLOAD MODULE

The solid state sensor protectors provide excellent protection against high motor temperatures resulting from locked rotor, loss of charge,

or motor overload. The combination of low voltage sensing and time delay provide positive protection against low voltage conditions which

can occur in the pilot circuit in the event of a single phase condition on a three phase circuit.
There are two major components in the protection system:
1.

The Protector Sensors

are mounted internally in the motor windings. The characteristics of the sensor are such that a change in temperature

causes a change in the sensor’s electrical resistance, the relation between temperature and resistance remains stable and exact, so that

calibration of the protection system can be made on the basis of resistance readings.

The Control Module

is a sealed enclosure containing a relay or triac, transformer, and several electronic components. Leads from the

internal motor sensors are connected to the module. As the motor temperature rises or falls, the resistance also rises or falls, triggering the

action of the control circuit at predetermined opening and closing settings.

DELAY TIMERS
Time Delay By-Pass (Low Pressure Switch Bypass):

When power is applied to the input, regardless of the state of the pressure switch,

the load is energized and timing begins. After the timing delay is complete, the pressure switch will control the load. The control is

reset by removing power during or after the time delay.

Anti-Short Cycle / Lockout Timer:

With application of power, the load is energized. When the thermostat opens or when there is a

loss of power, the load is de-energized and the delay period begins. The compressor will not start again during the delay period. The

ICM203 provides true thermostat interruption protection, even in the presence of a trickle current.

HOW TO RESET THE CONTROL SYSTEM

Whenever control system

has disable heating

(locked out)

power to

HPWH

unit must be turned off and on again to reset control system.

OPTIONAL FIELD SUPPLIED CONTROLS

• A field supplied low voltage momentary (reset) switch can be wired to the Control Board to reset the control system when it has

been disabled by a fault condition.

• A field supplied low voltage on/off switch can be added to turn the unit off. Note: high voltage would still be present inside the control

box,

turn of

f the main disconnect or breaker before performing any maintenance or service on the HPWH unit.

• The Control Board also has provision to activate field supplied external alarms (audible/visual) during a fault condition.
Call the toll free number listed on the back cover of this manual for technical assistance with any of these optional features.

HIGH PRESSURE

SWITCH LED

VAC

SUPP

VAC

OUT

T1 &

T2: 24

C SUPP

M1 & M2: PROVING CIRCUIT

(dry contact)

GREEN LED