Mammoth HP-5 Microprocessor Control User Manual download pdf (Page 4)

MAMM‐WHSP‐IOM‐1HP5A(October2011) 4

manually reset by interrupting power or by

removing the call for mechanical heating or

cooling. Intelligent reset automatically

terminates the lockout mode 5 minutes after a

lockout condition occurs. The purpose of

intelligent reset is to allow the unit to attempt to

reset itself if the condition that caused the

original lockout corrects itself. After 3 attempts in

a 6000 second (100 minute) period after the first

lockout, the intelligent reset feature is terminated

and the unit stays in lockout until the unit is

manually reset. The number of reset attempts is

limited to protect the unit from severe damage.

UNOCCUPIED (NIGHT SETBACK AND/OR

NIGHT SETUP) MODE: This mode is functional

with the auto changeover with night setback wall

thermostat and the auto changeover with night

setback/setup and override wall thermostat only.

The unoccupied mode allows the space to be

controlled at different settings. The unoccupied

mode can be activated in two ways:

 By closing the circuit between terminals

"COM" and "NS" via a field supplied switch

or time clock contacts (see Figure 1).

 By supplying 24 volts to terminals "COM"

and "NS".

In the unoccupied mode, the controller ignores

the normal fan and compressor signals from the

wall thermostat and only accepts a call for

compressor operation from the night

setback/setback portion of the wall thermostat.

The signal at terminals "COM" and "NS" can be

"daisy-chained” between many units. When the

signal to terminals "COM" and “NS” is removed,

the random start timing function is activated.

NIGHT SETBACK/SETUP INPUT FROM THE

THERMOSTAT:

Once the unoccupied mode is activated and the

occupied mode operation of the fan and

compressor are terminated, the controller can

only activate compressor operation from the wall

thermostat at terminal "3" (see Figure 2). Night

setback compressor operation occurs if the

space temperature falls to 12°F below the

occupied heating set point or if the space

temperature rises to 8°F above the occupied

cooling set point. The fan will automatically

operate and cycle with the compressor due to

the fan interlock feature.

OVERRIDE: The override feature is available

with the wall thermostat and is activated by the

push button on the face of the wall thermostat

(see Figure 3). When pushed, the unit will switch

back to its normal occupied temperature set

points on the wall thermostat for 2 hours. After 2

hours, the unit will resume its unoccupied mode

operation until the unoccupied mode signal is

removed from terminals "COM" and "NS". The

push button is only operable when the unit is in

the unoccupied mode.

EMERGENCY SHUTDOWN MODE: Emergency

shutdown allows the unit to be made inoperable

via a remote signal. The emergency shutdown

mode can be activated in two ways:

 By closing the circuit between terminals

"COM" and "ESD" via a field supplied set of

contacts (see Figure 4).

 By supplying 24 volts to terminals "COM"

and "ESD".

In shutdown mode, the reversing valve, fan and

compressor are inoperable, the lockout alarm

circuits are activated and the green LED flashes

repeatedly 2 times (quick ON and one long

OFF). The unit does not need to be reset. The

signal at terminals "COM" and "ESD" can be

"daisy-chained" between many units. When the

signal to terminals "COM" and "ESO" is

removed, the random start timing function is

activated.

AUXILIARY DRY CONTACTS: A pair of

normally open contacts at terminals "DRC IN"

and "DRC OUT” shall close and a pair of

normally closed contacts at terminals "DRC IN"

and "DRC OUT” shall open when the

compressor is energized. This will allow

connection of 24-volt power to the normally

closed contacts to supply power to a normally

open (powered close) motorized valve when the

compressor is on.

TEST PIN JUMPER: An on-board pair of male

terminals provides for an optional mode of

operation which defeats both forms of

compressor time delays. If a hard-wired jumper

is placed across the "TEST" and "TEST IN"

terminals, the random start time delay and the

compressor's five minutes of anti-short cycle

time delay will be ignored. However, the two,

four and six second time delays on the fan,

reversing valve and compressor remain in place.

LOW PRESSURE BYPASS: The dip switches

labeled “DY1” and “DY2” allow for four different

amounts of low pressure switch bypass: zero,

one, two and 3 minutes. The low pressure

bypass timer logic occurs anytime the board

senses a low pressure switch fault.

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Mammoth HP-5 Microprocessor Control User Manual Page 4

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