McQuay PE046 Installation Manual

GENERAL

UNIT NAMEPLATE

The Model PE less condenser centrifugal water chiller
has been factory assembled, checked and shipped with
a holding charge of R-12 refrigerant. The purchase
price of this equipment includes checkout of the unit
and initial startup by a McQuay service technician. An
integral part of the startup procedure includes instruc­tion of responsible personnel in the operation and
maintenance of this water chilling unit.

It is most important that this equipment be properly
operated and maintained if it is to perform the
operating service it was designed and built to provide.

McQuay offers equipment maintenance and/or inspec­tion programs that can be tailored to fit individual job
requirements. Information on the various service pro­grams is available through the McQuay Service De­partment or your local McQuay sales representative.

WARRANTY

The McQuay Model PE water chiller unit is covered by
a standard published warranty which covers parts only.
A complete published description of that warranty and
its limitations is provided in a warranty certificate
included with each unit.

First year warranty labor can be purchased separately,
check your local McQuay sales representative to
establish what additional coverage (if any) was pur­chased for your unit.

Whenever requesting information or assistance on the
Model PE chiller, the unit model number, shop order
number, and serial number should be copied from the
unit nameplate. A reproduction of this nameplate is

shown in Figure 3.

HOLDING

CHARGE

ONLY

STYLE
SERIAL
S.O. NO. PE-5210

\

-~

lPE5210-GO1

5NAl234~0

FACTORY CHARGED

~

LBS. REFRIGERANT

LEAK TEST PRESSURE 100

MOTOR - COMPRESSOR CONTROLLER

AND OVERLOAD PROTECTION FIELD

SUPPLIED. SEE SPEC.

R12

PSIG

PE-D4

mccbuw k.

198PlMHOl A

MADE IN U S A

Note Typical Serial Number

l Prior to January 1, 1983 =

1,

l

After

January

1983

LZ1320

=5NA1234500

INSTALLATION

Information pertaining to the installation of Model PE

water chilling units is available in Installation Bulletin

number PE-L-Gl. A copy of this manual was included

in the envelope shipped with the unit.

MODEL CODE

PE

063J

AN 30 R G A 2 L

UNlT FA::::E-I 1

SPEED CODE

MOTOR CODE

COMPRESSOR MOTOR VOLTAGE

~k;;~~;~;::~R

TYPE OF CHILLER
TUBING

CHILLER CODE

FIGURE 3. UNIT NAMEPLATE

OPERATING INFORMATION

OPERATOR’S RESPONSIBILITY

1.

Before operating the Model PE unit, become famil­iar with the machine and accessory equipment.

2.

If possible, arrange to attend a McQuay centrifugal
operators school.

After the unit has been checked out and approved

3.
for operation by a McQuay centrifugal service
technician, work with him to learn how to prepare
the system for startup. Start and stop the machine
a number of times while observing the operation of
the interlock function(s). The interlock circuit must

be satisfied before the compressor will run. After

operating the unit, place it in the shutdown mode.

Monitor operation and periodically inspect the

4.
equipment, making routine adjustments where
essa ry

nec-

Maintain a log of operating conditions on a daily

5.

basis. (Log sheets are available in pad form from

McQuay.

PRE-START SYSTEM CHECKLIST

p&q

All of the following will have been checked
out by the
during the initial startup procedure. *Items
should always be verified by the unit opera­tor on a routine basis during the operating
season.

A. UNIT

"1.

All service valves are in the operating position.
The control circuit is energized.

“2.

The oil heaters have been operating for a

“3.

minimum of 24 hours. Oil should be hot
(approximately 130 to 140

“4.

The oil charge is visible in the sight glass.
(Mark level on sight glass while machine is
shut down, check level weekly).

Check control circuit, verify that all safety

“5.

switches interrupt compressor starter holding
coil.

“6.

The water flow through the condenser is
correct. (This can be checked from condenser
water pressure drop curves available from

McQuay).

reduced by a plugged strainer which can

cause operating problems and nuisance
outs. New systems are generally susceptible

to blocked water strainers from foreign mate-

rial washing out of the piping.

B. ELECTRICAL

McQuay

On any system, water flow can be

startup technician

F).

trip-

All load equipment is operative (main system

“3.

fans, pumps, etc.).
Condenser fan(s) and controls are operative.

“4.

Condenser water bleed and water treatment

“5.

are adequate (if required).

STARTING

When the 115 volt AC control power supply is applied
to the control panel for the first time or after a power
failure has occurred, the following will take place.

1.

The oil sump heater(s) will be energized.
The external failure light will glow and the external

2.
“R9”)

alarm circuit (energized through Relay

activated.
Push the RESET Button on the control panel. The

3.

external failure light will go out and the external
alarm circuit will be reset (de-energized).

Set the compressor “ON-OFF” switch to “ON”, the

4.
light in this switch will glow. The unit control circuit

has been re-established.

The unit safety circuits have now been reactivated

5.
and the operating portion of the control circuit is

ready to function. (Before the operating portion of

the control circuit can function, the chilled water

pump will have to be running).
The “LRT” (unit cycling thermostat) will, on a call

6.

for chiller operation;

Start the oil pump. (Providing 20 minutes have
elapsed since the unit last stopped and the anti
recycle time delay has timed out and closed its
contacts).

will be

1.

The wire size is correct.

2.

The phase sequence is correct.

“3.

Voltage within plus or minus 10 percent of
rated compressor nameplate voltage.

“4.

Phase voltage unbalance 3 percent or less.

5.

All wiring connections correct per the unit
wiring diagram.

6.

All electrical connections are tight and made

with copper conductors and lugs.

“7.

All starter parts move freely and contacts meet
evenly.

8.

Motor overloads correct size (filled with dash-

C.

SYSTEM

“1. The condenser pump is rotating in the right

direction.

“2. The condenser pump and motor are lubricat-

ed.

When the oil pump develops oil pressure ade­quate to close the oil differential pressure switch

“OD”

(50

psig above suction pressure), the

switch will close.
A time delay relay “PLT” injects a 10 to 60

second time delay into the compressor starting
control circuit and prevents this portion of the
circuit from being energized while oil pressure is
being developed. At the end of this delay, if the
vane closed switch
gized the condenser pump relay “CWR” the
pump starter interlock contacts will close and
energize relay “MCR” located in the unit starter.
The compressor starter will now be energized
and the compressor will start.

“VC”

has closed and ener-

OPERATING

1. With the compressor running, capacity is controlled
by positioning variable inlet vane(s) located in the
suction gas inlet to the compressor. Opening the
vane(s) allows the compressor to pump more gas
and, as a result, increases capacity. Closing the
vane(s) reduces gas flow and reduces capacity. The

5

capacity control system is capable of modulating
the vane position to any capacity from 10 percent
to 100 percent.

The inlet vane(s) are controlled by means of 3
different devices. The capacity will always be
controlled by temperature unless the temperature
control is overridden by Items “b” or “c” below.

a. A temperature sensor located in the leaving

chilled water translates temperature changes
into an electrical signal and through the control
module loads or unloads the compressor (opens
or closes the vane(s).

b. The solid state control module in conjunction

with a current transformer and resistor located in

the compressor motor starter, senses and will
limit current drawn by the compressor motor
depending on the setting of the current limit
control. This controller will override the tempera­ture control and will, whenever motor current
exceeds its setting, open or close the compres­sor vane(s) in response to changes in current.
Whenever the motor current is less than the

setting on the current limit controller, unit
capacity control is returned to the temperature
sensor. The current limit control can be set to
limit current from 30 to 100 percent of name­plate full load current. The control is easily
adjusted by a knob on the face of the control

module.

c. The low pressure override switch “LPO” built

into the unit control panel senses suction pres­sure and is set to open at 2 to 5 psig above the
low pressure safety switch. Whenever the set­ting is reached, the override switch opens and in
turn de-energizes relay

gizes

“SA” and de-energizes “SB” solenoids in
the four way valve. Full oil pressure is applied to
the unloader piston driving the vanes closed.
This action will in most cases catch a momen­tary “sudden” drop in suction pressure such as

may be caused by a slow acting expansion

valve, a drop that without this unloading feature

would open the low pressure switch and stop

the compressor. The “LPO” pressure switch is

automatically reset, it will close when the pres­sure rises to a safe limit and return control of
capacity to the temperature sensor.

During normal operation, the compressor will con­tinue to operate and unload to a minimum of 10
percent until the cycling thermostat is satisfied.
When this occurs, the condenser relay
the motor control relay “MCR” are de-energized
and the compressor motor is stopped.

The unit oil pump will continue to run for a
minimum of one minute after the compressor
starter has been de-energized. This will assure

“R4”,

this in turn ener-

“CWR”

and

adequate lubrication for the compressor during the
spin down period.

In addition, on the next call for cooling, the
compressor capacity control vanes must be in a
closed position before the compressor is allowed to
restart. Contacts “VD” (auxiliary contacts located
in the compressor starter) through relay

energize the unload portion of the unit capacity

control circuit. If the vanes were not fully closed

when the compressor was stopped, oil pressure

will continue to be applied to the unloading piston

through the “SA” portion of the four-way solenoid

valve. This pressure continues to drive the vanes to

the closed position while the oil pump is still
running. This will permit the compressor with a
minimum delay to start on the next call for cooling.
(The compressor will not start until the vanes are in
the closed position).

Rapid cycling of centrifugal compressor motors is
not desirable. A time delay through relay “TDR” is
built into the unit control circuit to prevent rapid
cycling. Relay “TDR” will prevent the compressor
from restarting for a period of 20 minutes after the

compressor is stopped unless the “automatic re­start after power failure with reduced timed off

cycle” accessory option is used.

In the event of a power interruption during unit

operation,

damage by an emergency oil reservoir and spring

loaded piston. During normal operation enough oil

is stored in the emergency cylinder to lubricate the

bearings during spindown. The oil is forced into the
various passages by a spring loaded piston con­tained and compressed in the emergency oil cylin­der. ‘The spring is compressed by normal machine
oil pressure while the compressor is running and on
a loss of power is available along with the piston to
act as an emergency oil pumping device.

CONTROL CENTER
The control center contains all of the unit protective

controls and most of the operating devices. Table 1
“Control Summary” (on page
control information including electrical diagram sym-

bol, control description, setting, reset information,
location, signal light, and information on the control

function.

Eleven indicating lights are utilized on the unit control
panel. Nine of these lights are normally out and only
glow when a safety circuit has tripped.

Repeated tripping of a given control should be investi­gated by a competent air conditioning serviceman or
by a

McQuay
damage. Details of the control center are shown in
Figure 5.

the compressor is protected against

15)

contains general

service technician to avoid costly

“R8”

Two important safety circuits incorporated in the
control system are:

1.

GUARDISTOR
positive motor protection against damage from
motor overheating. Thermistors buried in the motor
winding are super sensitive to changes in motor
winding temperature. These thermistors have been
calibrated to de-energize the “GDR” (guardistor

relay) whenever the motor winding exceeds the
maximum allowable temperature.

The motor protection system, because it is sensing

internal motor winding temperature, provides posi-

tive protection against motor damage from such

heat causing problems as loss of motor cooling, low

voltage, etc. and, is in our opinion, the finest motor

protection system available.
The guardistor control circuit is a manual reset

system which when actuated will require manual
resetting by pushing the reset button on the unit
control panel.

MOTOR PROTECTION - Provides

[-X-l

The control module, through the capacity control
system, is capable of extremely close control of design

set point temperature. Dials provide for manual adjust­ment of the unit control set point and/or for limiting
the current drawn by the compressor motor at any
level between 30 and 100 percent of rated full load
current.

The pulsing action built into the electronic control
module, coupled with needle valve adjustment of the

hydraulic portion of vane control provides a very stable
temperature control arrangement. During normal oper­ation, it will take approximately 3 to 5 minutes to move
from minimum to maximum capacity and one
minute to move from maximum to minimum capacity.

The water chilling unit can be applied to many different
cooling applications and is adaptable to many different
types of control systems. The particular control ar-

rangement used will be incorporated as a part of the

total job control system. Details on the total system

control should be available in the job file. The vane

control system is explained starting on page 11.

(1)

In the event of a power failure to the unit or
control panel, the guardistor relay will trip
and require manual resetting when power is
restored.

2.

SURGEGARDTM- A surge or rotating stall is not a

normal operating condition for a centrifugal com­pressor. Under some abnormal unit operating con-

ditions, a compressor surge condition can develop
and, if allowed to continue, can cause compressor
damage. A surge is caused by many things, such as
dirty condenser tubes, reduction in condenser
water flow, increases in condenser water tempera­ture above design, or any other factor which can
act to increase the pressure difference between

suction and discharge pressure (head).

The

McQuay
against damage from surging by a unique protec­tion system which senses a surge condition, should

it occur,and shuts the

Whenever the machine has been stopped as a
result of a surge condition, the
cating

light on the control panel will glow.

SOLID STATE CAPACITY CONTROL

The solid state control module combines temperature
and current limit control in a single solid state package.
In addition, indicating lights on the module indicate
whether the control is calling for the compressor to
load or unload or whether the current override feature

is in control. By setting a switch, it is possible to place

the unit under manual or automatic control of un-

loading.

centrifugal compressor is protected

machine down

SurgeGardTMindi-

before

CONTROL MODULE CALIBRATION

The control module supplied as a standard part of the
unit control center is a solid state electronic device
which operates from a 24V A.C. power source. Except
for its external sensor(s) and a 5 volt (full load) signal
from a current transformer, and resistor located in the
compressor motor starter,
contained. The module can provide many features and
functions, some of which are:

1.

Proportional temperature control (within k 0.5F of

set point).

2.

Current limit control (manually adjustable).

3.

A pulse rate adjustment which permits the module

response speed for loading or unloading to be
varied to meet application requirements encounter­ed on different systems and/or applications.

4.

A “ramp-up” adjustment which can be utilized at
compressor startup to control the time to load and
the point at which the controlled loading begins.
For example, this adjustment can be used to reduce
the power that would be consumed by the unit if it
were allowed to load the machine without a time
restriction.

Indicating lights which glow when the controller is

5.
calling for loading (green), unloading (red) or
current override (amber).

A selector switch to permit manual or automatic

6.
control of unit capacity.

A selector switch to permit manual control of

7.

loading or unloading.
Can be adapted to accept a signal to reset the

8.

control point in response to a change occurring at

it is completely

self-

8

another location, such as outside air, return chilled
water or an energy management device.

Can be adapted to unload in response to a signal

9.
from an energy management device used to shed
electrical power loads. The compressor capacity
can be reduced as a function of building entrance

power.

CALIBRATION

The control module is factory calibrated and should

not normally require field calibration. In the event
calibration must be checked, a procedure covering the
steps required for both current and temperature
calibration is outlined in the following paragraphs.

CURRENT CALIBRATION

Equipment needed - an accurate

1.

ammeter.
Start the unit and place the control module

2.
selector switch in the manual position.

Open the starter door and place the

3.
the power lead drawing the highest current on the
load side of the starter.

4.

Remove the control module cover.
Set current demand limit selector switch clock-

5.
wise

(4)

against the stop (100%).

6.

Set the blue current limit calibration screw (located
just to the left of the temperature control stem) to
the full counterclockwise

7.

Check the compressor motor nameplate rated load
amperes (RLA against the amperage reading on
the

amprobe.
amperes drawn by the motor match the motor
rated load amperes.

When the nameplate and

8.
are equal, turn the current limit calibration screw
clockwise until the amber light just comes on and
stop. This places the unit in current hold. The
internal circuitry of the module will now insure
that, should the current increase to 105 percent of

rated load amperes, the controller will unload the

compressor.
To verify that the calibration is correct, manually

unload and then reload the compressor to the
rated load ampere value and verify that the current
override light glows. The current limit control
portion of the module is now in calibration.

Check the knob setting, if it needs correcting snap

9.
the top off the control knob, loosen the screw and

rotate the knob to indicate 100% of current.

Tighten screw and replace top.

Replace module cover, remove

IO.

starter door.

Manually adjust the load until the

(-1

position.

amprobe

amprobe

amprobe

amprobe

ampere values

and close

or

on

TEMPERATURE CONTROL CALIBRATION

Equipment required - accurate thermometer and

1.
DC voltmeter.

Remove control module cover.

2.
Allow unit to operate until leaving water tempera-

3.
ture stabilizes. With the thermometer located in
leaving chilled water, read the water temperature.

On the control module turn the temperature control

4.
knob to a point where both the unload (red) and
load (green) lights remain off. Move the knob to the
midpoint between these points.

Check voltage between control module terminals

5.
“IOM” and “COM” using the DC voltmeter. The
voltage reading should be close to 7.5V

Read the leaving water temperature once more.

6.

Check this temperature against the temperature
indicated by the pointer at the base of the tempera-

ture control stem. If they do not agree, hold the

stem and rotate the pointer until it indicates a
temperature on the scale corresponding to the

thermometer reading.

Replace the control module cover. Check the

7.

temperature indicated by the knob against the
cover temperature scale. If the reading is not
correct, snap the top off the knob, loosen the
screw and rotate the knob until it indicates the
correct temperature. Tighten the screw and replace
the top of the knob.

Remove the voltmeter and thermometer (if neces-

8.

sary). The temperature calibration is complete.

LUBRICATION SYSTEM
A separate motor driven oil pump assembly supplies oil

at controlled temperature and pressure to all bearing
surfaces and in addition is the source of hydraulic
pressure for the capacity control and emergency oil

supply.
The unit control system on a call for cooling will not

permit the compressor to start until oil pressure has
been established for at least one minute. When the
system controller is satisfied and stops the compres­sor, the oil pump runs for another minute to assure
adequate lubrication during spindown. In addition,
during this period the compressor is unloaded through
the action of the vane closed switch “VC”. The
compressor will then be ready to start unloaded on the

next call for cooling.

The oil pump is completely self-contained and located

in the oil sump. On Model SE046, 048 and 050 units, it
is located inside the compressor housing, for model

SE063 units the oil pump is located in the oil pump
assembly which is mounted at the rear of the unit
adjacent to the condenser.

(

+

0.5V).

9

FIGURE 5

In either case, it includes the pump, pump motor, oil
heater and oil separator. The Model SE063 includes
shut off valves for discharge, oil return and suction.

Oil is pumped through an externally adjustable oil relief
valve which is factory adjusted to limit the discharge oil
pressure from 100 to 110 psig above the operating
suction pressure. After leaving the relief valve, oil
flows through a refrigerant cooled oil cooler where the
temperature is reduced to approximately 90 to 100 F.
From the cooler it passes through a replaceable five

(5)
micron oil filter located in the compressor casting. On
Model SE046, 048 and 050 units the oil first passes
through the oil filter and thrust pump before entering
the oil cooler. Filtered oil is then distributed through
internal passages in the compressor casting to the
control system and before entering the bearings on
Model SE063 units it passes into the thrust pump
where the oil pressure to the bearings is boosted.

Oil leaving the compressor and motor bearings is re­leased under pressure into the low pressure gear hous­ing where some of this oil vaporizes. This oil vapor is
used to lubricate the gearing. The remaining oil leaving

the bearings drops to the bottom of the gear housing
where it is drained to the oil sump. On Model SE063

units oil from the gear housing and capacity control is
dumped into the scavenger line and returned to the oil

sump. Oil as it circulates in the oil system (because of

the ability of oil and refrigerant to mix in all propor­tions) will always have some refrigerant mixed in it.
Most of this refrigerant flashes from the oil as it enters
the oil sump or is driven from the oil by the oil heater.
This refrigerant gas as it is removed from the oil sump
passes through a centrifugal oil separator located on
top of the oil pump rotor.

10

The oil sump is vented to the suction side of the
system just ahead of the compressor wheel eye. Gas
flowing from the oil sump has to pass through the
spinning oil separator where entrapped oil is removed
by centrifugal force and is thrown back to the oil
sump. The refrigerant gas flows on through to the
compressor suction.

The main oil sump on all units is provided with an
electric heater and, in addition, the Model SE063 units
also include a heater in the gear housing.

THESE OIL HEATERS MUST REMAIN
ON AT ALL TIMES THE COMPRESSOR

IS NOT RUNNING. SHOULD AN EX-

TENDED POWER LOSS OCCUR

(DE­ENERGIZING THE HEATERS) AND AL­LOWING THE OIL TO COOL, IT WILL BE
NECESSARY WHEN POWER IS RE-

STORED TO KEEP THESE HEATERS

ENERGIZED FOR A MINIMUM OF 24
HOURS BEFORE ATTEMPTING TO RE-

START THE COMPRESSOR.

If conditions require the compressor to be restarted
immediately, it will be necessary to drain the system oil
and recharge the unit with new oil which is free of
refrigerant.

The low oil temperature thermostat “LOT” (set for 120

F)

supplied as part of the unit safety controls will, if

adjusted properly, prevent the compressor from start-

ing with cold oil. This thermostat is a manual reset

type and when tripped will cause the oil temperature

light to glow.
Quantities of oil required for Model SE units as well as

the recommended oil specifications are:

OIL CHARGE REQUIRED

MODELS PE046,048, and 050 1.75 gallons

MODEL PE063 . . . . . 8 gallons

RECOMMENDED OIL

SUNISO 4G/4GS

or TEXACO CAPELLA 68WF

EMERGENCY OIL SYSTEM
An oil cylinder with a spring loaded piston is incorpo-

rated in the compressor casting to supply emergency
lubrication for bearings in the event of a power loss.
During normal operation, pressure from the oil pump
fills the emergency oil cylinder and compresses the
piston/spring assembly contained in the cylinder. On a
loss of power (and as a result, a loss of oil pressure) oil
is forced into the bearing lubrication passages as the
spring behind the piston expands and forces oil from
the emergency cylinder. The emergency oil system
contains an adequate oil supply under pressure to
assure adequate bearing lubrication during the spin
down period.

CAPACITY CONTROL

Capacity variation for the unit is accomplished by
opening or closing vane(s) located in the suction inlet
to the compressor. Vane movement is controlled by
positioning a floating piston to which the inlet vane(s)
are linked. The piston (and as a result the vane(s) are
positioned by building up oil pressure on one side of
the piston and draining or not draining the other side,
depending on how far the piston must move to satisfy
the capacity requirements of the system.

Figures 6, 7 and 8 schematically illustrate the control of

the floating piston.

CONTROL SATISFIED

When the system capacity control is satisfied, an
electrical signal is sent to the control module calling for
no change in capacity. Such a condition is illustrated in

Figure 6. The control module has de-energized both
sections
valve. With both sections de-energized, ports Cl and
C2 are open and outlet port
full pressure to both sides of the piston holding it in a
stationary or satisfied position.

“SA” and “SB” of the four way solenoid

#3

is closed. This directs

riziq

COMPRESSOR
UNLOADER
CYLINDER

r

NOTE ADJUSTABLE

NEEDLE VALVES
INTEGRAL
WITH FOUR WAY
SOLENOID VALVE
ARE NOT SHOWN

IOPENlNG]

- OIL UNDER PRESSURE

-

FLOATING PISTON
LINKED TO INLET VANES

-

OPENS VANES

-

CLOSES VANES

FIGURE 6

-LEGEND-

OIL SUMP PRESSURE

SECTION “SA”
DE ENERGIZED

-

FROM OIL
PUMP
DISCHARGE
VALVE

INCREASE CAPACITY

When the unit capacity is not high enough to satisfy
the load (such a condition is illustrated in Figure

7),

a

signal from the control module will energize section

“SB” and de-energize section “SA”. This will drain oil

DRAIN FROM PISTON

--)

from the right hand side of the piston and allow it to

-

c

#3

OUTLET

0 c2

SECTION “SE”
ENERGIZED

SECTION “SA’

DE~ENERGIZED

move to the right and open the vanes. Oil in the right

hand side of the piston will continue to drain through

the open port C2 and outlet

#3.

The piston will
continue to move to the right until the control module
de-energizes section
that position.

“SB”

thus holding the piston at

FIGURE 7

TO OIL

I-

PUMP

SUMP

FROM OIL

*PUMP

DISCHARGE

DECREASE CAPACITY

When the unit has been running at a higher level of

capacity and the load falls off, the system is required
to reduce compressor capacity. Such a condition is
illustrated in Figure 8. The control module energizes
section

“SA” and de-energizes section

“SB”.

This

permits oil to drain from the left side of the piston

through open port Cl to the outlet

#3.

With section
“SB” de-energized, full oil pressure is applied to the
right end of the compressor piston, moving it to the
left. The piston can be stopped at any point in its
leftward movement when the capacity is satisfied and
the control module signals to de-energize “SA”.

The above descriptions are simplified versions of what

actually happens, neglecting the complicated control
function provided by the control module as it pulses to
control the action of solenoids

“SA” and ”SB”.

[CLOSlNGj

FIGURE 8

DISCHARGE
VALVE

11

METERING VALVES
The hydraulic control system utilizes needle type

adjusting valves built into the four way solenoid valve.
These valves are used to adjust the response time for
the floating piston to move through its full length of
travel. The valves are factory set and under normal
operating conditions should not need to be reset.
Attempts to reset the valves by unqualified personnel
will result in very poor operation of the capacity control
system.

MAINTENANCE

It is important that this unit and the air conditioning
system it is part of receive adequate maintenance if full
equipment life and all system benefits are to be
realized.

On a new system,
follow-up inspection of the system after 3 to 4 weeks
of normal operation. Such an inspection is not part of
the unit selling price. It can be provided by McQuay
service at additional cost.

FACTORY MAINTENANCE SERVICE

McQuay offers a variety of maintenance services
through its Nationwide Service Organization. These
contract services include regular inspections and emer­gency service by factory trained technicians. Services

are available around the clock to keep your equipment
running in top condition.

With a McQuay Assured Maintenance contract, all
parts, labor and materials are furnished
additional cost to the customer.

maintenance

should begin with a

. . .

with no

Model PE046, 046 and 050 units have an internal oil

pump and require that the system refrigerant
charge be pumped into the condenser before
attempting to change the filter. After the unit is
pumped down, break the seal on the oil filter access
cover and permit the pressure to bleed off before
removing the cover. After replacing the filter, crack

open the condenser liquid valve and permit the

pressure to build up and purge the oil filter housing.

Replace the cover and check for leaks.

Model PE063 units have an external oil pump

assembly. Close the oil pump discharge valve.

Loosen the flair fitting feeding oil to the filter and
bleed off the pressure by purging slowly. When the
pressure has been relieved, remove the cover and
replace the filter. When reassembling, vent as
much air as possible from the oil lines before
placing the compressor back into operation.

REFRIGERATION CYCLE
Since the Model PE unit has a semi-hermetic compres-

sor and utilizes R-12 or R-500 refrigerant, normal
system pressures, whether the system is operating or
shut down, will always be above atmospheric.

Unit maintenance generally will consist of proper
inspection and maintenance of an operating log. Visual
inspection of oil level as shown in the sight glass and

noting operating suction, discharge and oil pressures
will generally indicate if the unit operating characteris­tics are changing.

ELECTRICAL SYSTEM

It is widely recognized that a good maintenance
program is the essential first step in controlling energy
costs. And through McQuay’s Assured Maintenance
and Energy Management Programs, the owner is
assisted in establishing a comprehensive Energy Man­agement plan to meet his needs. For further informa­tion concerning the many services available, contact
your local McQuay service representative.

LUBRICATION

Once the unit has been checked out and is placed in

service, no additional oil should be required. the oil

level in the oil sight glass should be marked when the

system is shut down and the level checked periodical-

ly.

OIL FILTER

The oil filter must be changed annually. We do not

recommend that untrained personnel attempt to re­place the filter. The filter is contained in a system
under refrigerant as well as oil pressure. If proper care
is not taken when changing the filter personal injury
could occur. In addition air and/or moisture could
enter the system and cause equipment problems.

Generally, maintenance of the electrical system only

involves keeping operating controls clean and electrical
connections tight. In addition, the following items
should be inspected;

1.

The compressor amperage (current) drawn should
be compared to the nameplate rating. Normally, the
current read will be less than nameplate since the
nameplate value represents design full load current.

2.

Check that oil heaters are operative. Heaters are
cartridge type and can be checked by an amperage
reading. They should be energized whenever the
compressor is not operating. When the compressor

runs,

energized.

Once a year all safety controls except compressor

3.
overloads should be made to operate and the
control operating point checked. Any control as it
ages can shift its operating point and this should be
detected.

Pump interlocks and flow switches should interrupt

the control circuit cleanly

switch can be a source of trouble as well as
irritation.

the heater should be automatically

-

a chattering flow

de-

12

4. Motor starter contacts should be inspected and
cleaned annually. All terminal connections should
be tightened.

AUXILIARY EQUIPMENT

It

is important that auxiliary equipment used in
conjunction with the Model PE unit be adequately
maintained. Malfunctions in this equipment often
affect the operation of the condensing unit. For
example; improperly maintained air filters in the system
can restrict air flow to the cooling coils and as a result
cause suction pressure to fall to a point where a
nuisance trip out on the low suction pressure cutout
could occur. Items such as the following should be
checked and maintained.

1.

All filters must be cleaned or replaced. The fre­quency of this service will vary with different
installations.

2.

If evaporative type condenser is used, keep con­denser pump water strainer clean. Inspect and
service on a regular basis.

3.

Maintain condenser water treatment to limit buildup
of scale in condenser tubes (if required).

4.

Inspect condenser, clean when required. If unit has
a belt drive, change belts at least annually.

All fans and belts checked and adjusted.

5.

All condensate drains clean.

6.

7.

All motors lubricated.

8.

All electrical connections tight.

9.

All starter contacts are clean and mechanism moves
freely.

SEASONAL SERVICING

At the end of the cooling season and before the unit is
started in the spring, the following service procedures
should be completed.

A.

Annual Shutdown

When the unit may be exposed to freezing tempera-

1.

tures, water piping should be disconnected from
the supply and drained of all water. The chiller is
not self-draining; If all water must be drained from
the unit, remove the water heads and blow dry air
through each tube.

When it is possible to have the unit and/or piping
exposed to freezing temperatures, the only sure

method of protection is forced circulation of an

antifreeze solution through the water circuit.

When an evaporative condenser is used and the

2.
water pump will be exposed to freezing, be sure to
remove the pump drain plug and leave it out so that
any accumulation of water will drain away.

3.

Take measures to prevent the water supply line
shutoff valve from accidentally being turned on.

4.

Open the compressor disconnect switch and re­move the fusetrons. If a control circuit transformer
is used for unit control power, the disconnect must
remain on to supply power to the oil sump and gear
housing oil heaters. Set the compressor “on-off”
switch to “off”. To guard against the possibility of
an accidental compressor start, remove relay “R7”
from the control panel. (See Figure 4).

ANNUAL START UP

B.

Before commencing with the seasonal start up

1.
procedures, we recommend that the compressor
and oil pump motor resistance be checked. Annual
checking and recording of this resistance will
provide a record of deterioration in the motor
winding insulation should it occur. All new units
have a compressor
megohms between any motor terminal and ground.

Whenever a marked change in resistance shows or
uniform readings of less than 5 megohms are
obtained, THE UNIT SHOULD NOT BE STARTED

SINCE MOTOR FAILURE WOULD BE PRACTI­CALLY CERTAIN. In all probability, the motor will
have to be repaired or replaced. Your McQuay
service representative should be called for recom­mendations and/or repair.

The unit control circuit should have been energized

2.
at all times. If the control circuit has been shut off
and the oil is cool, the machine should not be
started until the heaters in the oil sump (and gear
casing PE063 only) have been energized for a
minimum of 24 hours. If it is necessary to start the
machine without waiting 24 hours, then the oil in

stator

resistance well over 100

the unit should be drained and replaced with fresh

oil.
Check and tighten all electrical connections.

3.
Install fusetrons in the main disconnect switch

4.
they have been removed).

Replace relay “R7” (if it was removed).

5.
Replace drain plug in water pump if it had been

6.
removed.

Reconnect water lines, turn on supply water and

7.
check for leaks.

If evaporative type condenser is used, clean and

8.

flush the sump.

a. Make sure condenser bleed is adequate.
b. Be sure water treatment is adequate to prevent a

buildup of solids in the condenser. Air circulated
through the condenser contains many contami-

nants which are flushed out by the water sprays.
The use of untreated water in most installations

(if

13

can result in a reduction of heat transfer in the
condenser tubes or damage to the tubes as a
result of corrosion, erosion, sliming, scaling, or
algae formation. (This section applies to systems
with evaporative type condensers.)

RECOMMENDATION
The service of a competent water treatment organi-

zation be obtained to determine what, if any, water
treatment is required and their recommendations
implemented.

Mcquay assumes no responsibility for operating

problems or damage occurring as a result of

untreated condenser water.
Clean all surfaces and remove all litter. A clean well

9.

maintained unit is the sign of a good operator.

REPAIR OF THE SYSTEM

Information on pumping unit down, pressure testing,
leak testing, evacuation and charging is contained in
installation manual SE-Gl.

OPERATOR’S CHECKLIST

UNIT CHECKS

1. Suction, discharge and oil pressure normal.

2.

Oil level correct.
Voltage within tolerance (plus or minus 10 percent

3.
of compressor nameplate ratings). Phase unbalance
does not exceed 3 percent.

4.

Motor amperage proper for load conditions.

Vanes open and close under manual and automatic

5.
control.

Motor current limiting control operational.

6.

Safety interlocks interrupt compressor operation.

7.

Unit cycling thermostat set 3 to 5 degrees below

8.

unit control set point.

SYSTEM CHECKS

1.

All motors checked for voltage and running
amperes.

All pumps and motors lubricated.

2.

Water strainer(s) clean.

3.
All fans checked, belts tight, bearings lubricated.

4.

Air filters clean.

5.

All electrical connections tight, starter contacts

6.

clean, starter movement proper.

14