THDC IOM 0707
A e r o S y s I
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Installation and Maintenance Instructions THDC Series Remote Condensing Unit Congratulations on selecting a THDC condensing unit from AeroSys. With proper installation and maintenance, your system will provide you with years of satisfactory operation. This system is compatable with a properly sized and Laboratory Listed direct expansion indoor air handler.
Site Preparation and Installation To insure a satisfactory air supply, locate condensing units in a clean area, away from loose dirt and foreign matter that may clog the coil. The condensing unit’s coil/blower side must not be located near any exhaust of steam, hot air, grease or corrosive fumes. The condensing unit should be located at least 30 inches from a wall, adjacent unit or other obstruction that may restrict accessibility for maintenance. For multiple unit installations, space the units so that the hot exhaust air is not directed toward the air inlet of an adjacent unit. Install on a solid base, capable of supporting the weight of the condensing unit. The base should be higher than the surrounding grade and larger than the dimensions of the condensing unit base. The base of the unit is sloped to drain water away from the maintenance access side of the equipment. When installing Blower Motor
Condenser Blower
the unit(s), make sure to maintain the drainage angle toward the coil side of the condensing unit. Maximum recommended refrigerant line length is 50 feet. Condenser Air Ducting (if used) The total external static pressure for the inlet and outlet ducts, including grille, must not exceed 0.5 inches of water. If the condensing unit draws ducted air from the outside of the building, rain hoods must be installed. In addition, install screens over rain hood openings to eliminate the possibility of birds, water, or debris entering the unit. Normal operating sound may be objectionable if the condensing unit is placed directly over quiet work areas. Use flexible ductwork or nonflammable cloth collars to attach ductwork to the unit and to control vibration transmission to the building. Locate the unit and ductwork so that the discharge air does not short circuit to the condenser air inlet.Avoid directing the hot exhaust air toward adjacent doors or windows.
Suction Line Service Valve
Electrical Connections Each unit ships from the factory with all internal wiring completed. Refer to the electrical schematic when making connections.
Liquid Line Service Valve
! WARNING! UNIT CONTAINS HAZARDOUS ELECTRICAL VOLTAGE. DISCONNECT POWER SUPPLY BEFORE WORKING ON IT. THE LINE SIDE OF DISCONNECT REMAINS ENERGIZED WHEN DISCONNECT IS “OFF”. Electrical connections necessary for the condensing unit at the installation site are:
Electric Box
1) Power supply to the condensing unit line side contactor,
32 Thomas Johnson Drive - Frederick, Maryland 21702
2) 24 VAC Control wiring between the evaporator unit and the condensing unit, again connected to the condensing unit contactor coil. Power Connections All power and control wiring and ground connections must be in accordance with the National Electrical Code and local codes. Refer to unit nameplate for voltage, wire size and circuit protection requirements. USE COPPER CONDUCTORS ONLY The outdoor condensing unit requires its own power source and earth ground, with a disconnect switch (field supplied) to isolate the unit for maintenance. Route the supply power to the disconnect switch and then through one of the cabinet’s holes to the unit’s contactor. Connect an earth ground to the lug provided in the electric junction box. Control Connections A field-supplied 2 wire control connection (24VAC) is required between the evaporator and the condensing unit. Control wiring must be installed in accordance with the National Electrical Code (NEC), Class 1 circuit. Control wiring between the evaporator and the condensing unit must not allow a voltage drop in the line of more than 1 volt (16 gauge minimum for 75 feet). Piping Connections Two refrigerant lines, an insulated copper suction line and a copper liquid line, are required between the evaporator and the condensing unit. A refrigerant drier must be installed in the liquid line. When piping to the unit’s refrigerant service valves, wrap the service valves with a wet rag to prevent damage to the valve.
Motor Capacitor
Field pressure testing evacuation, and refrigerant charging may be done through the side ports on the suction and liquid line service valves. These ports are open to the field side of the piping. After field evacuation, open both service valves (back valve stem out) all the way for proper system operation. Refrigeration piping should be installed with high temperature brazed joints. ALWAYS use damp rags wrapped around the valve body to protect the valve from heat damage.Good refrigeration practices should be employed for piping supports, leak testing, dehydration, and charging of the refrigeration circuits. Vibration isolating supports should be used to isolate the refrigeration piping from the building. Pack a soft flexible material around tubing to prevent damage when sealing openings in walls and to reduce vibration transmission. NOTE ON TRAPS When installing remote condensing units above the evaporator, the suction gas line should be trapped at the evaporator. This trap will retain refrigerant oil in the off cycle. When the unit starts, oil in the trap is carried UP the vertical riser and returns to the compressor. When installing remote condensing units below the evaporator, the suction gas line should be trapped with an inverted trap the height of the evaporator. This prevents refrigerant migration to the compressor during off cycles. Refrigerant Pressures Suction and discharge pressures will vary with load and ambient conditions. Normal pressures are: Suction pressure 58-75 psig. Discharge pressure 180-275 psig at 95o F Superheat 12-18o F
Maintenance
Electric Box Ground Lug
Contactor
Each year the components of the refrigeration system should be inspected for proper function and signs of wear. Since in most cases evidence of malfunction is present prior to component failure, periodic inspections can be a major factor in the prevention of most system failures. Electric Panel The electric panel should be cleaned and inspected annually for any loose electrical connections.
Compressor Capacitor
24 VAC Contactor coil Connections
High Voltage Contactor Connections
Direct Drive Blower Package Blower impellers should be thoroughly inspected and any debris removed. Check to see if they are tightly mounted on the fan shaft and do not rub against the fan housing during rotation.
32 Thomas Johnson Drive - Frederick, Maryland 21702
Once every year add 3 drops of SAE 20 weight non-detergent oil to each of the two oil holes on the fan motor if your system is supplied with oil ports. Air Distribution Since all unit models are designed for constant volume air delivery, any unusual air flow restrictions must be avoided. Restricted airflow through the condenser coil will reduce the operating efficiency of the unit. Additionally, it can result in high compressor head pressure and loss of cooling. Using compressed air or a commercial coil cleaner, clean the
condenser coil of all debris that will inhibit airflow. In winter, do not permit snow to accumulate around the side or underneath the condenser. Check for bent or damaged coil fins and repair as necessary. Check all refrigerant lines and capillaries for vibration and support as necessary. Carefully inspect all refrigerant lines for signs of oil leaks. Refrigeration System Inspect refrigerant lines every year for signs of wear and proper support.
Trouble Shooting Guide Symptom
Possible Cause
Evaporator Coil Low airflow Ices 1) Dirty filters 2) Blower rotating backwards 3) Motor speed too low Also see “Low 4) Discharge louvers closed Suction Pressure” Thermostat located in wrong location for additional information Temperature setting too low
Possible Remedy 1) replace filters 2) reverse rotational wires 3) increase motor speed setting 4) open louvers Move thermostat to measure return air temp. Increase temp setting
Air short cycling back to return air inlet Obstruction below discharge louvers, redirect air pattern
Low Suction Pressure Also see “Evaporator” Coil Ices” for additional information
System low on charge
Add refrigerant
Leak in refrigerant piping
Find and repair leak
Expansion device stuck or clogged
Remove and replace or clean valve
Drier/strainer clogged
Remove and replace drier/strainer
System low on charge
Add refrigerant
Leak in refrigerant piping
Find and repair leak
Expansion device stuck or clogged
Remove and replace or clean valve
Drier/strainer clogged
Remove and replace drier/strainer
Temperature setting too low
Increase temp setting
Inadequate initial charge
Add refrigerant
Inadequate air flow
See “Low airflow” above
Condensing temperature too low
32 Thomas Johnson Drive - Frederick, Maryland 21702
Symptom Noisy Compressor
Possible Cause
Possible Remedy
Head pressure too high
See section for “Condenser pressure too high”
Condenser pressure too high
See section for “Condenser pressure too high”
Expansion valve open(Liquid “slugging”) Abnormally cold suction lineFeeler bulb loose; tighten& insulate
Condenser Head Pressure too High
Compressor “short cycles”
System over charged
Recover excess refrigerant
Vibration mounts tight
Loosen vibration mount nuts
Worn or scarred compressor bearings
Replace Compressor
Broken compressor valves
Replace Compressor
Restricted air flow at outside heat exchanger
Remove restriction for airflow. Wall sleeve installed incorrectly.
Condenser air discharge recirculating to condenser coil inlet
Deflect air discharge away from condenser coil inlet
Access panel not on unit, air not passing over condenser coil
Put condenser access panel on unit
Debris on condenser coil
Clean debris away; clean condenser coil
Low motor RPM
Increase fan motor speed settings
High static pressure to condenser fan
Check and remove fan restrictions
System is over charged
Recover excess refrigerant
Condenser fan running in reverse
Reverse fan rotation
Non-condensable gas (or wrong refrigerant) in refrigerant system
Recover refrigerant, evacuate system and recharge with new gas. Install new drier/strainer
Condenser fan not operating
Defective contactor motor or capacitor. Replace contactor, motor and/or capacitor
Defective contactor, motor or capacitor
Replace contactor, motor and/or capacitor
Dirty or iced evaporator coil
Clean coil, See “Evaporator Coil Ices” above
Compressor cycling on high or low pressure switches (if supplied)
Check and replace switch(es) if defective
Low voltage to compressor
Check voltage to system and correct.
Loose power terminal
Tighten electrical terminals
Compressor cycling on internal overloads
Check for, and correct: Low suction pressure, high suction and/or discharge temperature, voltage out of operating range, defective run capacitor
32 Thomas Johnson Drive - Frederick, Maryland 21702
THDC 36 = 50 MFD
:$//6/((9( 237,21$/
$
(;7(5,25%8,/',1*685)$&( 68&7,21$1'5(7851 5()5,*(5$17/,1(67
n
c
o
r
p
o
r
a
t
e
d
Installation and Maintenance Instructions THDC Series Remote Condensing Unit Congratulations on selecting a THDC condensing unit from AeroSys. With proper installation and maintenance, your system will provide you with years of satisfactory operation. This system is compatable with a properly sized and Laboratory Listed direct expansion indoor air handler.
Site Preparation and Installation To insure a satisfactory air supply, locate condensing units in a clean area, away from loose dirt and foreign matter that may clog the coil. The condensing unit’s coil/blower side must not be located near any exhaust of steam, hot air, grease or corrosive fumes. The condensing unit should be located at least 30 inches from a wall, adjacent unit or other obstruction that may restrict accessibility for maintenance. For multiple unit installations, space the units so that the hot exhaust air is not directed toward the air inlet of an adjacent unit. Install on a solid base, capable of supporting the weight of the condensing unit. The base should be higher than the surrounding grade and larger than the dimensions of the condensing unit base. The base of the unit is sloped to drain water away from the maintenance access side of the equipment. When installing Blower Motor
Condenser Blower
the unit(s), make sure to maintain the drainage angle toward the coil side of the condensing unit. Maximum recommended refrigerant line length is 50 feet. Condenser Air Ducting (if used) The total external static pressure for the inlet and outlet ducts, including grille, must not exceed 0.5 inches of water. If the condensing unit draws ducted air from the outside of the building, rain hoods must be installed. In addition, install screens over rain hood openings to eliminate the possibility of birds, water, or debris entering the unit. Normal operating sound may be objectionable if the condensing unit is placed directly over quiet work areas. Use flexible ductwork or nonflammable cloth collars to attach ductwork to the unit and to control vibration transmission to the building. Locate the unit and ductwork so that the discharge air does not short circuit to the condenser air inlet.Avoid directing the hot exhaust air toward adjacent doors or windows.
Suction Line Service Valve
Electrical Connections Each unit ships from the factory with all internal wiring completed. Refer to the electrical schematic when making connections.
Liquid Line Service Valve
! WARNING! UNIT CONTAINS HAZARDOUS ELECTRICAL VOLTAGE. DISCONNECT POWER SUPPLY BEFORE WORKING ON IT. THE LINE SIDE OF DISCONNECT REMAINS ENERGIZED WHEN DISCONNECT IS “OFF”. Electrical connections necessary for the condensing unit at the installation site are:
Electric Box
1) Power supply to the condensing unit line side contactor,
32 Thomas Johnson Drive - Frederick, Maryland 21702
2) 24 VAC Control wiring between the evaporator unit and the condensing unit, again connected to the condensing unit contactor coil. Power Connections All power and control wiring and ground connections must be in accordance with the National Electrical Code and local codes. Refer to unit nameplate for voltage, wire size and circuit protection requirements. USE COPPER CONDUCTORS ONLY The outdoor condensing unit requires its own power source and earth ground, with a disconnect switch (field supplied) to isolate the unit for maintenance. Route the supply power to the disconnect switch and then through one of the cabinet’s holes to the unit’s contactor. Connect an earth ground to the lug provided in the electric junction box. Control Connections A field-supplied 2 wire control connection (24VAC) is required between the evaporator and the condensing unit. Control wiring must be installed in accordance with the National Electrical Code (NEC), Class 1 circuit. Control wiring between the evaporator and the condensing unit must not allow a voltage drop in the line of more than 1 volt (16 gauge minimum for 75 feet). Piping Connections Two refrigerant lines, an insulated copper suction line and a copper liquid line, are required between the evaporator and the condensing unit. A refrigerant drier must be installed in the liquid line. When piping to the unit’s refrigerant service valves, wrap the service valves with a wet rag to prevent damage to the valve.
Motor Capacitor
Field pressure testing evacuation, and refrigerant charging may be done through the side ports on the suction and liquid line service valves. These ports are open to the field side of the piping. After field evacuation, open both service valves (back valve stem out) all the way for proper system operation. Refrigeration piping should be installed with high temperature brazed joints. ALWAYS use damp rags wrapped around the valve body to protect the valve from heat damage.Good refrigeration practices should be employed for piping supports, leak testing, dehydration, and charging of the refrigeration circuits. Vibration isolating supports should be used to isolate the refrigeration piping from the building. Pack a soft flexible material around tubing to prevent damage when sealing openings in walls and to reduce vibration transmission. NOTE ON TRAPS When installing remote condensing units above the evaporator, the suction gas line should be trapped at the evaporator. This trap will retain refrigerant oil in the off cycle. When the unit starts, oil in the trap is carried UP the vertical riser and returns to the compressor. When installing remote condensing units below the evaporator, the suction gas line should be trapped with an inverted trap the height of the evaporator. This prevents refrigerant migration to the compressor during off cycles. Refrigerant Pressures Suction and discharge pressures will vary with load and ambient conditions. Normal pressures are: Suction pressure 58-75 psig. Discharge pressure 180-275 psig at 95o F Superheat 12-18o F
Maintenance
Electric Box Ground Lug
Contactor
Each year the components of the refrigeration system should be inspected for proper function and signs of wear. Since in most cases evidence of malfunction is present prior to component failure, periodic inspections can be a major factor in the prevention of most system failures. Electric Panel The electric panel should be cleaned and inspected annually for any loose electrical connections.
Compressor Capacitor
24 VAC Contactor coil Connections
High Voltage Contactor Connections
Direct Drive Blower Package Blower impellers should be thoroughly inspected and any debris removed. Check to see if they are tightly mounted on the fan shaft and do not rub against the fan housing during rotation.
32 Thomas Johnson Drive - Frederick, Maryland 21702
Once every year add 3 drops of SAE 20 weight non-detergent oil to each of the two oil holes on the fan motor if your system is supplied with oil ports. Air Distribution Since all unit models are designed for constant volume air delivery, any unusual air flow restrictions must be avoided. Restricted airflow through the condenser coil will reduce the operating efficiency of the unit. Additionally, it can result in high compressor head pressure and loss of cooling. Using compressed air or a commercial coil cleaner, clean the
condenser coil of all debris that will inhibit airflow. In winter, do not permit snow to accumulate around the side or underneath the condenser. Check for bent or damaged coil fins and repair as necessary. Check all refrigerant lines and capillaries for vibration and support as necessary. Carefully inspect all refrigerant lines for signs of oil leaks. Refrigeration System Inspect refrigerant lines every year for signs of wear and proper support.
Trouble Shooting Guide Symptom
Possible Cause
Evaporator Coil Low airflow Ices 1) Dirty filters 2) Blower rotating backwards 3) Motor speed too low Also see “Low 4) Discharge louvers closed Suction Pressure” Thermostat located in wrong location for additional information Temperature setting too low
Possible Remedy 1) replace filters 2) reverse rotational wires 3) increase motor speed setting 4) open louvers Move thermostat to measure return air temp. Increase temp setting
Air short cycling back to return air inlet Obstruction below discharge louvers, redirect air pattern
Low Suction Pressure Also see “Evaporator” Coil Ices” for additional information
System low on charge
Add refrigerant
Leak in refrigerant piping
Find and repair leak
Expansion device stuck or clogged
Remove and replace or clean valve
Drier/strainer clogged
Remove and replace drier/strainer
System low on charge
Add refrigerant
Leak in refrigerant piping
Find and repair leak
Expansion device stuck or clogged
Remove and replace or clean valve
Drier/strainer clogged
Remove and replace drier/strainer
Temperature setting too low
Increase temp setting
Inadequate initial charge
Add refrigerant
Inadequate air flow
See “Low airflow” above
Condensing temperature too low
32 Thomas Johnson Drive - Frederick, Maryland 21702
Symptom Noisy Compressor
Possible Cause
Possible Remedy
Head pressure too high
See section for “Condenser pressure too high”
Condenser pressure too high
See section for “Condenser pressure too high”
Expansion valve open(Liquid “slugging”) Abnormally cold suction lineFeeler bulb loose; tighten& insulate
Condenser Head Pressure too High
Compressor “short cycles”
System over charged
Recover excess refrigerant
Vibration mounts tight
Loosen vibration mount nuts
Worn or scarred compressor bearings
Replace Compressor
Broken compressor valves
Replace Compressor
Restricted air flow at outside heat exchanger
Remove restriction for airflow. Wall sleeve installed incorrectly.
Condenser air discharge recirculating to condenser coil inlet
Deflect air discharge away from condenser coil inlet
Access panel not on unit, air not passing over condenser coil
Put condenser access panel on unit
Debris on condenser coil
Clean debris away; clean condenser coil
Low motor RPM
Increase fan motor speed settings
High static pressure to condenser fan
Check and remove fan restrictions
System is over charged
Recover excess refrigerant
Condenser fan running in reverse
Reverse fan rotation
Non-condensable gas (or wrong refrigerant) in refrigerant system
Recover refrigerant, evacuate system and recharge with new gas. Install new drier/strainer
Condenser fan not operating
Defective contactor motor or capacitor. Replace contactor, motor and/or capacitor
Defective contactor, motor or capacitor
Replace contactor, motor and/or capacitor
Dirty or iced evaporator coil
Clean coil, See “Evaporator Coil Ices” above
Compressor cycling on high or low pressure switches (if supplied)
Check and replace switch(es) if defective
Low voltage to compressor
Check voltage to system and correct.
Loose power terminal
Tighten electrical terminals
Compressor cycling on internal overloads
Check for, and correct: Low suction pressure, high suction and/or discharge temperature, voltage out of operating range, defective run capacitor
32 Thomas Johnson Drive - Frederick, Maryland 21702
THDC 36 = 50 MFD
:$//6/((9( 237,21$/
$
(;7(5,25%8,/',1*685)$&( 68&7,21$1'5(7851 5()5,*(5$17/,1(67
