A Guide To Operating and Maintaining Your
Dual Fuel Heat Pump Unit
NOTE TO INSTALLER
This manual should be left with the equipment owner.
FOR YOUR SAFETY
Do not store or use gasoline or other
flammable vaporsand liquids in the vicinity of this or any other appliance.
Improperinstallation,adjustment,alteration,service or maintenance can cause injury or propertydamage. Refer to thismanual. For assistance
or additional information, consult a qualified installer, service agency, or the gas supplier.
FOR YOUR SAFETY
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not
use any phone in your building.
• Immediately call your gas supplier from
a neighbor’s phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier,
call the fire department.
Before performing recommended maintenance,
be sure gas supply and main power switch to
unit are turned off.Electrical shock could cause
personal injury.
48HX Unit Without Base Rail
48HX Unit With Optional Base Rail
48HX
Dual Fuel Heat Pump Units
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 4
Tab 5a 5a
PC 111 Catalog No. 564-908 Printed in U.S.A. Form 48HX-1SO Pg 1 12-94 Replaces: New
WELCOME TO EFFICIENT
YEAR-ROUND COMFORT
Congratulations on your excellent choice and sound investment in home comfort!
Your new dual fuel heat pump represents both the latest in
engineering development and the culmination of many years
of experience from one of the most reputable manufacturers
of comfort systems.
Your new unit is among the most reliable home comfort products available today. To assure its dependability, spend just
a few minutes with this booklet now. Learn about the operation of your dual fuel heat pump and the small amount of
maintenance it takes to keep it operating at its peak
efficiency.
With minimal care, your dual fuel heat pump will provide
you and your family with satisfying home comfort — both
now and for years to come.
IMPORTANT FACTS
To better protect your investment and to eliminate unnecessary service calls, familiarize yourself with the following
facts:
Improper installation, adjustment, alteration, service,maintenance, or use can cause explosion, fire, electrical shock,
or other conditions which may cause personal injury or
property damage. Refer to this manual. For assistance
or additional information consult a qualified installer,
service agency, distributor, or branch. The qualified installer or agency must use only factory-authorized kits
or accessories when modifying this product.
• Your dual fuel heat pump system should never be operated without a clean air filter properly installed. Plan to inspect the filter periodically.A clogged air filter will increase
operating costs and shorten the life of the unit.
• Supply-air and return-air registers should not be blocked.
Drapes, furniture, and toys are some of the items commonly
found obstructing grilles. Restricted airflow lessens the unit’s
efficiency and life span.
• Outdoor units must have unrestricted airflow.Do not cover
the unit, lean anything against it, or stand upon it. Do not
allow grass clippings, leaves, or other debris to accumulate
around or on top of the unit. Maintain a 12-in. minimum
clearance between the outdoor unit and tall grass, vines, shrubs,
et cetera.
• Your multipurpose indoor thermostat is the control center
for your dual fuel heat pump system. You should familiarize
yourself with its proper operation. Attempting to control the
system by other means — for instance, switching the electrical supply power ON and OFF — may cause damage to
the unit.
• Thermostat ‘‘jiggling’’causes rapid-cycling, which is potentially damaging to the compressor. Do not move the temperature selector on the thermostat for any reason for at least
5 minutes after the compressor has shut off.
• You may find that you can maintain greater personal comfort by running the fan continuously. ‘‘Air pockets’ ’canform
due to the structure of the building, placement of registers,
et cetera. These air pockets may be too cool or warm
for your liking. Continuous fan operation minimizes any temperature differences.Also, systems equipped with electronic
air cleaners and/or humidifiers offer the added benefits of
having the air continuously cleaned year-round, and humidified during the winter season.
• Your dual fuel heat pump will remove humidity from your
home during the cooling season. After a few minutes of operation, you should be able to see water trickle from the condensate drain. Check this occasionally to be sure the drain
system is not clogged. Of course, don’t expect to see much
drainage if you live in a very dry climate.
OPERATING YOUR DUAL FUEL HEAT PUMP
The operation of your dual fuel heat pump is controlled by
the indoor thermostat. You simply adjust the thermostat and
it maintains the indoor temperature at the level you select.
Most thermostats for the dual fuel heat pump systems
include temperature control selector, FAN switch, and
SYSTEM switch. EMERGENCY HEAT (EM HEAT) setting also is provided with the SYSTEM switch. See Fig. 1.
The temperature control selector is a dial or lever that allows
you to establish the temperature that you wish to maintain
for your personal comfort. Some thermostats possess twotemperature control selectors: one for setting the temperature desired during the cooling cycle, and one to set the heating
operation temperature. Typical settings are 78 degrees Fahrenheit for cooling and 68 degrees for heating.
The FAN switch of ferstwo options for controlling the blower:
AUTO and ON.When set to AUTO, the blower will run during the time the dual fuel heat pump is operating. When the
FAN switch is set at the ON position, the blower will run
continuously.
Typically,the SYSTEM switch on your thermostat offers the
following selections: COOL, OFF, HEAT, and EMERGENCY HEAT. Your thermostat may also have another selection, AUTO. The heat pump will not operate when the
SYSTEM switch is set at the OFF position. With the SYSTEM switch set at COOL, your heat pump will operate in its
cooling mode when the indoor temperature rises above the
level that you wish to maintain. With the SYSTEM switch
set at the HEAT position, your dual fuel heat pump will provide warmth whenever the indoor temperature falls below
the level that you have selected.
The AUTO selection found on some thermostats provides
for automatic changeover between cooling and heating cycles.
Withthe SYSTEM switch set in theAUTO position, the cooling mode is activated when the indoor temperature rises above
the thermostatcooling temperature setting, or the heating mode
will be activated when the indoor temperature drops below
the thermostat setting for the heating cycle.
Your home comfort system includes supplementary gas heat.
Your system will turn on gas heat only as necessary to meet
your heating needs during defrost cycles or when outdoor
temperatures are low. In the event of a heat pump malfunction, you can use the EMERGENCY HEAT setting on your
thermostat to manually select gas heat. Heat pump heating
is deactivated when EMERGENCY HEAT is selected. If it
becomes necessary to use EMERGENCY HEAT to provide
heat, call your dealer for service as soon as is practical.
See your thermostat owner’s manual for additional
information.
2
Cooling Cycle — When operating in the cooling cycle,
your dual fuel heat pump will run until the indoor temperature is lowered to the level you have selected. On extremely
hot days, your dual fuel heat pump will run for longer periods at a time and have shorter ‘‘off’’ periods than on moderate days.
The following are typical conditions that add extra heat
and/or humidity to your home. Your heat pump will work
longer to keep your home comfortable under these
conditions:
• Entrance doors are frequently opened and closed
• Laundry appliances are being operated
• A shower is running
• More than the usual number of people are present in the
home
• More than the normal number of electric lights are in
use
• Drapes are open on the sunny side of the home
Heating Cycle — With the SYSTEM switch of your in-
door thermostat set to the HEAT position, the dual fuel heat
pump will operate in its heating mode until room temperature is raised to the level you have selected. Of course, the
heating unit will have to operate for longer periods to maintain a comfortable environment on colder days and nights
than on moderate ones.
DEFROST CYCLE — When your dual fuel heat pump is
providing heat to your home and the outdoor temperature
drops below 45 degrees Fahrenheit, moisture may begin to
freeze on the surface of the outdoor coil. If allowed to build
up, this ice would impede airflow across the coil and reduce
the amount of heat absorbed from the outside air.So, to maintain energy-efficient operation, your dual fuel heat pump has
an automatic defrost cycle.
Depending on which model you have, the defrost cycle starts
at a preset time interval of 30, 50, or 90 minutes. However,
it may be reset. Defrost will start at the preset time only if
the ice is sufficient to interfere with normal heating
operation.
After the ice is melted from the outdoor coil, or after a maximum of 10 minutes in the Defrost mode, the unit will automatically switch back to normal heating operation.
Do not be alarmed if steam or fog appears at the outdoor
unit during the defrost cycle. Water vapor from the melting
ice may condense into a mist in the cold outside air.
EMERGENCY HEAT— The EMERGENCY HEAT setting
on your thermostat refers to supplementary gas heating that
is included in your home comfort system. Operation of the
EMERGENCY HEAT source may be required if the heat
pump malfunctions.
The red light on your thermostat will glow if the
SYSTEM switch is moved from HEAT to the EMERGENCY HEAT setting. This indicates that the heat pump is
off and the supplemental gas heating is selected for
operation.
Also, your particular model of heat pump may include a
Service Sentry™ circuit, which is used with a thermostat that
includes a red warning light. The red warning light will glow
if the compressor malfunctions. Call your dealer for immediate service if you suspect trouble.
TO LIGHT UNIT
Your dual fuel heat pump is equipped with an automatic
direct spark ignition and power combustion blower.
Do not attempt to light by hand; personal injury may
result.
1. Do not turn off the electrical power to unit without
first turning off the gas supply.
2. Before attempting to start the gas heating section, familiarize yourself with all the procedures that must
be followed.
If you do not follow these instructions exactly, a fire or
explosion may result, causing property damage, injury,
or loss of life.
Refer to Fig. 2. See Fig. 3 for location of gas valve. Refer
to Fig. 4 while proceeding with the following steps.
Step 1 — Set the temperature selector on room thermo-
stat to the lowest temperature setting and set SYSTEM switch
to EM HEAT.
Step 2 — Close the external manual shutoff valve.
Step 3 — Turn off the electrical supply to the unit.
Step 4 — Remove the burner access panel with a
5
⁄16-in.
nut driver.
Step 5 — Turn the control dial on the internal gas valve
counterclockwise to the OFF position and wait
5 minutes.
Step 6 — Turn the control dial on the internal gas valve
clockwise to the ON position.
Step 7 — Replace the burner access panel.
Step 8 — Turn on the electrical supply to unit.
Step 9 — Open the external manual shutoff valve.
Fig.1—Typical Thermostat
3
Step 10 — Set the temperature selector on room thermo-
stat slightlyabove room temperature to start unit. The induceddraft combustion-air fan will start. Main gas valve will open
and main burners should ignite within 5 seconds. If the burner
does not light within 5 seconds, the ignition module will go
into a Retry mode after a period of approximately 22 seconds (following the 5-second ignition period).
If the burners do not light within 15 minutes of the initial
call for heat, there is a lockout.
Step 11 — Set the temperature selector on room ther-
mostat to desired setting.
1. If the main burners fail to light, or the blower fails
to start, shut down gas heating section and call your
dealer for service.
2. Never attempt to manually light the main burners on
unit with a match, lighter, or any other flame. If the
electric sparking device fails to light the main burners, refer to the following shutdown procedures, then
call your dealer as soon as possible.
Failure tofollow these requirements couldresult in serious
personal injury.
TO SHUT UNIT OFF
Do not turn off the electrical power to unit without first
turning off the gas supply.
Failure to follow these procedures can result in serious
fire or personal injury.
NOTE: If unit is being shut down because the heating season has ended, make sure to turn on power to cooling
system.
If unit is being shut down because of a malfunction, call
your dealer as soon as possible.
Should overheating occur or the gas supply fail to shut
off, shut off the manual gas valve to the unit before shutting
off the electrical supply.
Do not use this unit if any part has been under water. Immediately call a qualified service technician to inspect the
unit and to replace any part of the control system and any
gas control which has been under water.
Refer to Fig. 5 while proceeding with the following steps.
Step 1 — Set the temperature selector on room thermo-
stat to lowest temperature setting and set SYSTEM switch
to OFF.
Step 2 — Close the external manual shutoff valve.
Step 3 — Turn off the electrical power supply to the unit.
Step 4 — Remove the burner access panel.
Step 5 — Turn the control dial on the internal gas valve
counterclockwise to the OFF position.
Step 6 — Replace the burner access panel.
Step7— Restore electrical power to the unit and set SYS-
TEM switch to COOLto ensure operation of the cooling system during the cooling season.
ROUTINE MAINTENANCE
All routine maintenance should be handled by skilled, experienced personnel. Your dealer can help you establish a
standard procedure.
For your safety, keep the unit area clear and free of combustible materials, gasoline, and other flammable liquids and
vapors.
To assure proper functioning of the unit, flow of combustion and ventilating air must not be obstructed from reaching
the unit. Clearance of at least 30 in. is required on all sides
except the duct side.
MAINTENANCE AND CARE FOR THE
EQUIPMENT OWNER
Before proceeding with those things you might want to
maintain yourself, please carefully consider the following:
1. TURN OFF GAS SUPPLY AND ELECTRICAL
POWER TO YOUR UNIT BEFORE SERVICING
OR PERFORMING MAINTENANCE.
2. Do not turn off electrical power to this unit without
first turning off the gas supply.
3. When removing access panels or performing maintenance functions inside your unit, be aware of sharp
sheet metal parts and screws. Although special care
is taken to reduce sharp edges to a minimum, be extremely careful when handling parts or reaching into
the unit.
Air Filters — Air filter(s) should be checked at least ev-
ery 3 or 4 weeks and changed or cleaned whenever it becomes dirty. Dirty filters produce excessive stress on the blower
motor and can cause the motor to overheat and shut down.
Table 1 indicates the correct filter size for your unit. Refer
to Fig. 6 to access the filter(s).
To replace or inspect filter(s) (or accessory filter rack when
supplied):
1. Remove the filter access panel using a
5
⁄16-in. nut driver.
2. Remove the filter(s) by pulling the filter(s) out of the unit.
If the filter(s) is dirty, clean or replace with new one.
When installing the new filter(s), note the direction of the
airflow arrows on the filter frame.
If you have difficulty in locating your air filter(s), or if
you have questions concerning proper filter maintenance, contact your dealer for instructions. When replacing filters, always use the same size and type of filter that was supplied
originally by the installer.
BURNER
ACCESS PANEL
Fig. 2 — Dual Fuel Heat Pump
4
Table 1 — Indoor-Air Filter Data
UNIT SIZE
48HX
030,036 048,060
Filter Size 24x24 24x30
Never operate your unit without filter(s) in place. Failure to heed this warning may result in damage to the
blower motor and/or compressor. An accumulation of
dust and lint on internal parts of your unit can cause
loss of efficiency and, in some cases, fire.
Heat Exchanger — To ensure dependable and efficient
heating operation, the heat exchanger should be checked by
a qualified maintenance person before each heating season,
and cleaned when necessary. This checkout should not be
attempted by anyone not having the required expertise and
equipment to properly do the job. Checking and/or cleaning
the heat exchanger involves removing the gas controls assembly and the flue collector box cover and, when completed, reinstalling the gas controls assembly for proper operation. Also, the flue collector box cover must be replaced
correctly so that a proper seal is maintained. Contact your
dealer for the required periodic maintenance.
Fans and Fan Motor — Periodically check the con-
dition of fan wheels and housings and fan-motor shaft
bearings. No lubrication of outdoor- or indoor-fan bearings
or motors is required or recommended.
Indoor and Outdoor Coils — Cleaning of the coils
should only be done by qualified service personnel. Contact
your dealer for the required annual maintenance.
Condensate Drain — The drain pan and condensate
drain line should be checked and cleaned at the same time
the cooling coils are checked by your dealer.
Compressor— All compressors are factory-shipped with
a normal charge of the correct type refrigeration grade oil
and should rarely require additional oil. The service person
must be certain the proper oil level is maintained in the compressor when it is installed and running.
Outdoor Fan
Do not poke sticks, screwdrivers, or any other object
into revolving fan blades. Severe bodily injury may
result.
The fan must be kept free of all obstructions to ensure proper cooling. Contact your dealer for any required
service.
Electrical Controls and Wiring — Electrical con-
trols are difficult to check without proper instrumentation;
therefore, if there are any discrepancies in the operating cycle,
contact your dealer and request service.
Refrigerant Circuit — The refrigerant circuit is diffi-
cult to check for leaks without the proper equipment; therefore, if inadequate cooling is suspected, contact your local
dealer for service.
Combustion Area and Vent System — The com-
bustion area and vent system should be inspected visually
before each heating season. The normal accumulation of dirt,
soot, rust, and scale can result in loss of efficiency and improper performance if allowed to build up.
If your unit makes an especially loud noise when the
main burners are ignited, shut down the gas heating section and call your dealer.
Proceed as follows to inspectthe combustion area and powerventing system of your unit.
1. Turn off electrical power and gas supply to your unit.
2. Remove burner access panel. (See Fig. 2.)
3. Using a flashlight, carefully inspect the burner areas for
dirt, soot, rust, or scale. See Fig. 3.
If dirt, soot, rust, or scale accumulations are found,
call your dealer and do not operate your heating section.
4. When you have completed your inspection, follow the
start-up procedures in this manual to restore your unit to
operation.
5. Observe unit heating and emergency heating operations.
Components in heat section may be hot after unit
has been started up. When observing flame, be careful not to get close to or touch heating components
or serious personal injury may result.
Watch the burner flame to see if it is bright blue. If you
observe a suspected malfunction or if the burner flames
are not bright blue, call your dealer.
6. Replace burner access panel.
BURNERS
GAS VALVE
FLUE HOOD
Fig. 3 — Gas Heat Section Detail
5
STEP 1
STEP 2
STEP 3
STEP 4
STEP 5
STEP 6
STEP 7
STEP 8
STEP 9
STEP 10
Fig.4—ToLight Unit
6
STEP 1
STEP 2
STEP 3
STEP 4
STEP 5
STEP 6
STEP 7
Fig.5—ToShut Unit Off
7
UnitPanels— After performing any maintenance or serv-
ice on the unit, be sure all panels are fastened securely in
place to prevent rain from entering unit cabinet and to prevent disruption of the correct unit airflow pattern.
REGULAR DEALER MAINTENANCE
In addition to the type of routine maintenance you might
be willing to perform, your unit should be inspected regularly by a properly trained service technician. An inspection
(preferably each year, but at least every other year) should
include the following:
1. Inspection of all flue product passages — including the
burners, heat exchanger, and flue collector box.
2. Inspection of all combustion- and ventilation-air passages and openings.
3. Close inspection of all gas pipes leading to and inside of
your unit.
4. Inspection and, if required, cleaning of the outdoor and
indoor coils.
5. Inspection and, if required, cleaning of the indoor drain
pan.
6. Inspection and cleaning of blower wheel housing and
motor.
7. Inspection of all supply-air and return-air ducts for leaks,
obstructions and insulation integrity.Any problems found
should be resolved at this time.
8. Inspection of the unit base to ensure that no cracks, gaps,
etc., exist which may cause a hazardous condition.
9. Inspection of the unit casing for signs of deterioration.
10. Inspection of all electrical wiring and components to assure proper connection.
11. Inspection for leaks in the refrigerant circuit. Pressurecheck to determine appropriate refrigerant charge.
12. Inspection of compressor oil level.
13. Operational check of the unit to determine working conditions. Repair or adjustment should be made at this time.
Your servicing dealer may offer an economical service contract that covers seasonal inspections. Ask for further
details.
Complete service instructions can be found in the unit
Installation, Start-Up and Service Instructions.
WARRANTY
The 48HX warranty is located at the back of this book. Be
sure to read the warranty carefully to determine the coverage for your unit.
BEFORE YOU CALL FOR SERVICE,
CHECK FOR SEVERAL EASILY-SOLVED
PROBLEMS
If insufficient heating or cooling is suspected:
( ) Check for sufficient airflow. Check the air filter for dirt.
Check for blocked return-air or supply-air grilles. Be sure
they are open and unobstructed. If these checks do not reveal the cause, call your servicing dealer.
If your unit is not operating at all, check the following list
for easy solutions:
( ) Check to be sure that your thermostat temperature selector is set above the indoor temperature during the heating
season, or below the indoor temperature during the cooling
season. Be sure the system switch is in the proper HEAT or
COOL position and not in the OFF position.
( ) Is the electrical supply switch ON?Are any fuses blown,
or has the circuit breaker tripped?
( ) During the heating season, check the external manual
shutoff valve. Is this lever parallel with the pipe, indicating
that the valve is open? Or is the lever at a right angle,
indicating that the valve is closed? If closed, has the gas been
shut off for safety reasons? Otherwise, you may open the
valve and follow the start-up procedures listed in this manual.
NOTE: Before proceeding with the next check, turn OFF
the gas supply, then the electrical power supply to the unit.
Remove the control access door.
( ) During the heating season, check the control dial on the
internal gas valve. Is it in the ON position? If it is not, be
sure it was not turned off for the purpose of safety. If no
safety hazards exist, follow the start-up procedures in this
manual.
( ) If your unit still fails to operate, call your servicing dealer
for troubleshooting and repairs. Specify the model and serial
numbers of your unit. (Record them in this manual in the
space provided.) If the dealer knows exactly which unit you
have, he may be able to offer suggestions over the phone, or
save valuable time through knowledgeable preparation for
the service call.
IN CASE OF TROUBLE
If after performing the above and unit performance is still
unsatisfactory, shut off the unit and call your dealer.
Dealer’s Name
Telephone
Unit Model
Unit Serial Number
FILTER ACCESS PANEL
Fig.6 — FilterAccess Panel —Vertical SupplyShown
8
DETACHAND MAIL PRODUCT REGISTRATION
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Copyright 1994 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book 1 4
Tab 5a 5a
PC 111 Catalog No. 564-908 Printed in U.S.A. Form 48HX-1SO Pg 12 12-94 Replaces: New
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