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Installation

32

 AH-SVX008C-EN

System Settings and 
Adjustments

Low/High Pressure Limit Switch

Air conditioning systems using DX refrigerant are 
equipped with hermetically sealed high-pressure and low-
pressure switches. These switches are pre-set by the 
manufacturer and cannot be adjusted.

R407C Pressure Switch Settings

High-pressure switch: opens at 410 psig and has a manual 
reset.

Low-pressure switch: opens at 10 psig (± 4) and closes at 
32 psig (± 5) and has an automatic reset.

Head Pressure Controls-Air Cooled 
Systems

Condenser Fan Cycling (Condenser Model 
SCS-AA, 0°F)

Used for outdoor installations where ambient condenser 
air inlet temperatures are 0°F or higher, this method 
utilizes a high-pressure differential control switch with 
SPST (Single Pole, Single Throw) contacts and an 
automatic reset. The switch activates the condenser fan 
contactor when the dis- charge pressure reaches a 
predetermined value to maintain the condensing 
temperature.

See the Head Pressure Controls section of the SCS Series 
Remote Air Cooled Condensers IOM for information about 
the fan cycling pressure control settings (cut-in and cut-out 
pressures) for the supported refrigerants. Note that the 
pressure values vary according to both the refrigerant type 
and the number of fans in the SCS unit.

Condenser Multi-Speed Fan Switch (Model 
HES-CAA, 0°F)

Used for indoor installations where ambient condenser air 
inlet temperatures are 0°F or higher, the condenser fan 
speed switch senses refrigerant discharge pressure and 
changes the condenser fan speed to maintain proper 
condenser pressures.

The condenser fan speed switch changes the fan from low 
to high speed when pressure rises and returns the fan 
from high speed to low speed when the pressure lowers.

Variable Condenser Fan Speed (Condenser 
Model SCS-SA, -20°F)

Used for outdoor installations where ambient 
temperatures may fall to -20°F, a variable speed condenser 
fan motor control is used to maintain head pressure. The 
variable speed motor is located closest to the header end 
of the condenser. The fan speed control is a continual 
modulation of the motor's speed. The controller is factory 
installed in the outdoor condenser/condensing unit. The 
fan speed controller requires no adjustment.

The fan speed controller will automatically control the 
head pressure at a level to maintain design refrigerant 
discharge pressures. On systems with more than one fan 
on the condenser, the remaining motors cycle on and off 
based on pressure.

Intelligent Control (Condenser Model SCS-EC 
Only, -20°F)

Used for outdoor installations where ambient condenser 
air inlet temperatures may fall to -20°F, intelligent pressure 
control is designed to maintain discharge pressure by 
constantly modulating condenser fan speed. SCS outdoor 
condensers are equipped with highly efficient, 
electronically commutated (EC), axial fan(s). The EC fan 
speed is infinitely variable up to full speed. The control 
system uses refrigerant pressure transducer(s) to monitor 
refrigerant discharge pressure and control the EC fan(s) to 
the precise speed needed to maintain design refrigerant 
discharge pressures.

Flooded Head Pressure Control

(Condenser Model SCS-AA With Fan Cycling, -30°F)

Used for outdoor installations where ambient condenser 
air inlet temperatures may fall to -30°F, flooded head 
pressure control is designed to maintain head pressure 
during low ambient conditions. A head pressure control 
valve and a receiver are used in the refrigeration circuit to 
back up liquid refrigerant into the condenser coil. The head 
pressure control valve is a 3-way modulating valve 
controlled by discharge pressure.

When the A/C unit begins to operate, the discharge 
pressure rises (to approximately 320 psig for R407C) and 
the condenser fan is cycled on, as described in 

“Condenser Fan Cycling (Condenser Model SCS-AA, 0°F),” 
p. 32

. When ambient temperature drops, the discharge 

pressure drops also. When the discharge pressure drops, 
the head pressure control valve diverts discharge gas 
away from the condenser to the receiver. Liquid flow from 
the condenser is restricted, causing liquid to back up in the 
condenser.

Flooding the condenser reduces the area available for heat 
transfer. The desired result is to increase the pressure into 
the condenser, maintaining a minimum discharge 
pressure during low ambient operation, thus ensuring 
proper condensing temperature. The head pressure 
control valve requires no adjustment.

While the fan is running, the flooded head pressure control 
valve modulates the amount of discharge gas entering the 
receiver. As the pressure increases, the valve diverts more 
discharge gas to the condenser, allowing more liquid to 
flow from the condenser to the receiver.

When using this method of head pressure regulation there 
must be enough refrigerant in the system to ensure 
adequate charge at the lowest expected ambient 
temperature in which the system will be operating. A 
receiver is used to store the extra refrigerant when the 
condenser is not using it.

Summary of Contents for CeilAir CW

Page 1: ... equipment The installation starting up and servicing of heating ventilating and air conditioning equipment can be hazardous and requires specific knowledge and training Improperly installed adjusted or altered equipment by an unqualified person could result in death or serious injury When working on the equipment observe all precautions in the literature and on the tags stickers and labels that a...

Page 2: ...ent that is used in these service procedures In addition some states or municipalities may have additional requirements that must also be adhered to for responsible management of refrigerants Know the applicable laws and follow them WARNING Proper Field Wiring and Grounding Required Failure to follow code could result in death or serious injury All field wiring MUST be performed by qualified perso...

Page 3: ...low the company s Environmental Health and Safety EHS policies when performing work such as hot work electrical fall protection lockout tagout refrigerant handling etc Where local regulations are more stringent than these policies those regulations supersede these policies Non Trane personnel should always follow local regulations Introduction AH SVX008C EN 3 Copyright This document and the inform...

Page 4: ...rmostat 22 Air Cooled Split Systems 22 Optional Equipment 26 System Charging Procedures 27 Water Glycol Systems 27 Pump 27 DX Unit Charging Requirements 27 Refrigerant Characteristics 30 Pressure Temperature Settings 30 Saturated Refrigerant Pressure Tables 31 System Settings and Adjustments 32 Low High Pressure Limit Switch 32 Head Pressure Controls Air Cooled Systems 32 Blower Adjustment 33 Comm...

Page 5: ...Table of Contents AH SVX008C EN 5 spection 46 Technical Support 46 Obtaining Warranty Parts 46 Obtaining Spare Replacement Parts 47 Appendix A TR OHS Preventive Maintenance Inspection Checklist 48 ...

Page 6: ...C Chilled Water System G Glycol Cooled W Water Cooled Digit 11 12 Options AWS Alternate Water Source FC Free Cooling LP Low Profile Configuration SF Same Face Air Pattern SP Special Configuration About Digits Model numbers are comprised of digits Each digit or set of digits defines the product model Example using model TR OHS 040 H G FC Overhead System OHS digits 1 2 3 4 5 40 000 MBH Capacity digi...

Page 7: ...net configuration is available in a 2 ft x 4 ft frame for units ranging from 12 000 to 40 000 Btu h spot cooler or ducted or a larger frame for units ranging from 48 000 to 120 000 Btu h ducted only For ducted units there are three configurations of airflow patterns dependent on unit 90o right angle straight through and in out same face see Figure 9 p 14 Refer to the installation drawing provided ...

Page 8: ...the electrical drawing supplied with your unit for details specific to your system Optional Equipment Humidistat Dehumidistat As an option for systems employing an A Tech 1 1 or A Tech 1 2 thermostat a room mounted humidistat and or dehumidistat can be shipped loose for field installation Each device has an adjustment dial on the front where the operator selects the desired setpoint If an optional...

Page 9: ...ir temperature indicative of a fire The system shuts down either through the controller or in an A Tech system via connection to the TR OHS remote stop start terminals Following activation the firestat must be manually reset using the reset button on the firestat before restarting the unit Water Detector As an option Trane offers spot type or strip cable type water detectors In units equipped with...

Page 10: ...oint to increase above the prevailing ambient conditions The indoor units inlet fluid temperature sensor monitors the fluid temperature and deactivates the free cooling mode once the fluid temperature increases above the user adjustable enable setpoint The compressor system becomes the primary cooling source and will activate if the return air temperature increases above the setpoint AWS Operation...

Page 11: ...ssor cut out setpoint temperature is reached provided the minimum run time expires Ifthechilledwaterinlettemperaturerisesabove55oF AWS cooling turns off the control valve closes When the DX cooling stage enable temperature setpoint is reached the compressor turns on and becomes the primary source of cooling In the event of loss of water flow during AWS operation the AWS control valve is closed and...

Page 12: ...er to the National Electrical Code and local codes To minimize the effects of the environment surrounding the conditioned space certain steps must be taken This is especially true for critical precision room preparation computer rooms labs requiring close tolerance control of temperature and humidity The conditioned space should be well insulated and include a vapor barrier The installer should en...

Page 13: ... a secure location where the unit cannot be tampered with and the power service switch cannot be inadvertently turned off Locate the remote condenser condensing unit where the fan is not likely to draw dirt and debris into the coil fins There should be at least one equipment width of clearance around the condenser to ensure adequate airflow to the coil Secure the condenser condensing unit so the s...

Page 14: ...If using the supplied anchors drill two 3 16 in holes and tap in the wall anchors If only the screws are being used drill two 3 32 in holes 4 Fasten the base to the wall using the supplied screws 5 Connect wiring between the thermostat and equipment See the A Tech wiring instructions in Section A Tech1 1ProgrammableThermostat p 22 and A Tech 1 2 Programmable Thermostat p 22 6 Reinstall thermostat ...

Page 15: ...ockable handle to lock power out during maintenance periods The switch is typically mounted to the A C cabinet however it may be shipped loose for field installation The case has a top keyhole mounting slot and two holes in each bottom corner for mounting The hardware for mounting the switch is field supplied Select suitable fasteners for the intended mounting surface The non fused service switch ...

Page 16: ...ear the common return air grille Mount the humidistat and dehumidistat at least 18 in froman outside wall and approximately 5 ft above the floor Controlsmay be installed either ona flushswitch box or on a surface switch box Followthe steps below for mounting Instructions for wiring the unit are provided in Section Humidistat Dehumidistat p 26 1 Pull dial knob off loosen screw located at bottom of ...

Page 17: ... rivets or self tapping screws Piping Connections Refrigerant Self Contained Systems No refrigeration connections are required for self contained air water or glycol cooled systems Models TR OHS 012 040 AS TR OHS 012 120 C and TR OHS 012 120 W G Split Systems Split air cooled systems will require field refrigeration piping All split systems are shipped with a dry nitrogen charge of 100 psig System...

Page 18: ...R407C refrigerant Model No Total Btu h Capacity Compressor to Condenser O D in 50 ft or less 100 ft or less 150 ft or less 012 12 000 1 2 5 8 5 8 018 18 000 1 2 5 8 5 8 024 24 000 5 8 5 8 3 4 032 32 000 5 8 3 4 3 4 040 40 000 3 4 3 4 7 8 048 48 000 3 4 7 8 7 8 048D 48 000 5 8 5 8 3 4 060 60 000 3 4 7 8 1 1 8 072D 72 000 5 8 3 4 3 4 084D 84 000 3 4 7 8 7 8 120D 120 000 3 4 7 8 1 1 8 Table 4 Recomme...

Page 19: ...suction lines must be insulated to prevent condensation from forming on the pipes Refer to the Recommended Suction Line and Recommended Liquid Line sizing tables Chilled Water Water Glycol and Hot Water Reheat Piping The piping connections for water glycol chilled water and systems with hot water reheat are sweat connections Pipe sizes may not necessarily be the same as the unit connection Piping ...

Page 20: ...tionsuppliedbythefactory Refertotheinstallation drawing provided with your unit for the size and location of the connection The humidifier requires normal tap water as the water supply If the supply water is high in particulates an external filter may be needed NOTICE Humidifier Damage Do not use demineralized water in the humidifier Note Refer to the humidifier operator s manual supplied with the...

Page 21: ...nit can operate with a tolerance of 5 if the following change is performed The control transformers within the system must have the primary wire connected to its respective 240V tap instead of the 208V tap Single Phase Units 277V Single phase units require that the hot leg of power be connected to terminal L1 and the neutral wire to terminal L2 of the main power distribution block Three Phase Unit...

Page 22: ... to the control terminal board located within the unit electric box The thermostat provides a terminal strip with box type lugs for wire connections See Figure 18 p 23 and refer to the supplied electrical drawing for proper wire terminations Figure 16 A Tech 1 1 top and 1 2 bottom controller wiring contacts Air Cooled Split Systems The system interconnecting field wiring illustrations in Figure 19...

Page 23: ...Figure 17 A Tech 1 1 control wiring W1 Y1 Figure 18 A Tech 1 2 control wiring A TECH 1 2 Installation AH SVX008C EN 23 ...

Page 24: ...URE ARE NOTIONAL SEE UNIT ELECTRICAL DRAWING FOR ACTUAL NUMBER AND TERMINAL POINTS OF CONDUCTORS Figure 20 Interconnection field wiring remote condensing unit SEE NOTE 3 REMOTE CONDENSING UNIT REMOTE TEMPERATURE HUMIDITY SENSOR OPTIONAL SEE NOTE 3 3 CONDUCTOR SHIELDED CABLE E CONTROLLER DISPLAY E DISPLAY PLUGS DIRECTLY INTO THE CONTROLLER INSIDE THE ELECTRIC BOX 6 CNDCT PHONE TYPE NON SHIELDED CAB...

Page 25: ...OR COUNTS IN FIGURE ARE NOTIONAL SEE UNIT ELECTRICAL DRAWING FOR ACTUAL NUMBER AND TERMINAL POINTS OF CONDUCTORS Figure 22 Interconnection field wiring glycol systems SEE NOTE 3 REMOTE TEMPERATURE HUMIDITY SENSOR OPTIONAL SEE NOTE 3 3 CONDUCTOR SHIELDED CABLE E CONTROLLER DISPLAY E DISPLAY PLUGS DIRECTLY INTO THE CONTROLLER INSIDE THE ELECTRIC BOX 6 CNDCT PHONE TYPE NON SHIELDED CABLE THERMOSTAT C...

Page 26: ...trical drawing s supplied with your unit to determine the exact number of field wires and proper wireterminations requiredspecifically foryour system Remote Shut Down The unit provides an interface that allows for remote shut down A normally closed switch rated at 5 amperes at 24VAC is required for this purpose Two conductors from the normally closed switch must be connected to the control termina...

Page 27: ...foaming due to air in the system Pump If a pump is used ensure the system is filled before turning the pump on If the pump is not self priming it is important that there is pressure at the suction inlet NOTICE Pump Damage Do not run the pump when dry If the pump has no pressure on the discharge side leave the discharge valve partially shut to create a back pressure in the pump so that liquid can b...

Page 28: ...ed by adding the amount of refrigerant required for the condenser see the condenser manual provided separately plus the refrigerant piping Table 6 p 28 plus the refrigerant for the A C unit Table 7 p 28 The values in Table 8 p 31 are the estimated weights for the compressor circuit In the case of dual compressor systems the values are estimated weights for each compressor circuit The values shown ...

Page 29: ...he system to stand for two hours with the dry nitrogen charge This gives time for the nitrogen molecules to disperse in the system absorbing moisture 6 After two hours release the pressure Then turn on the vacuum pump and evacuate the system a second time down to 150 microns or less Close the vacuum pump isolation valve and pressurize the system again with dry nitrogen and allow the system to stan...

Page 30: ...e suction side to achieve the sub cooling temperature 6 If the unit has hot gas reheat optional the previous steps are still followed except the hot gas reheat valve must be open to allow refrigerant to flow into the reheat coil to obtain the proper amount of refrigerant charge This can be done using the system controller to enable a call for dehumidification lower the humidity setpoint This proce...

Page 31: ...llation AH SVX008C EN 31 Saturated Refrigerant Pressure Tables The following table shows the refrigerant pressures are provided for reference for R407C refrigerant Table 9 Refrigerant vapor tables R407C Refrigerant Temp F Pressure psig Saturated Evaporating Temperature 20 37 9 Dew Point Saturated Vapor 22 40 1 24 42 3 26 44 7 28 47 1 30 49 6 32 52 1 34 54 8 36 57 5 38 60 3 40 63 2 42 66 1 44 69 2 ...

Page 32: ...an one fan on the condenser the remaining motors cycle on and off based on pressure Intelligent Control Condenser Model SCS EC Only 20 F Used for outdoor installations where ambient condenser air inlet temperaturesmay fallto 20 F intelligentpressure control is designed to maintain discharge pressure by constantly modulating condenser fan speed SCS outdoor condensers are equipped with highly effici...

Page 33: ...ure or increase the water glycol flow A directional arrow is stamped on the metal housing of the valve stem 350 psig and 450 psig High Pressure Valves Adjustment is made by turning the round holed knob counter clockwise inside the valve s metal housing to increase condensing pressure or decrease water glycol flow and clockwise to decrease the condensing temperature or increase the water glycol flo...

Page 34: ...vels to the condenser No adjustment to the valve is necessary Hot Gas Bypass Optional The two most common systems provided by Trane for hot gas bypass are snap acting and full floating described below Snap Acting Hot Gas Bypass The snap acting hot gas bypass system provides for some modulated capacity control and freeze protection The hot gas bypass system includes a discharge bypass valve that al...

Page 35: ...ot exceed 20 F superheat Exceeding this temperature may cause failure of the compressor The normal control setting for the quench valve is 20 F superheat when there is no call for cooling The valve is factory set and no adjustment should be necessary If adjustment is required remove adjustment cap from the valve Turn the adjusting stem clockwise to increase superheat and counterclockwise to decrea...

Page 36: ...e discharge air temperature 6 Test humidifier operation by creating a demand for humidification Use an amp meter to determine the current draw of the humidifier Visually check for vapor leaving the steam head or feel if the cylinder is warm to verify the humidifier is operational In all cases one to six hours might be required to see a desired level or rise in humidity in the conditioned space Onc...

Page 37: ...he refrigerant on the scale before starting recovery 7 Start the recovery machine and operate in accordance with manufacturer s instructions 8 Do not overfill cylinders They should contain no more than 80 volume liquid charge 9 Do not exceed the maximum working pressure of the cylinder even temporarily 10 When the cylinders have been filled correctly and the process completed make sure that the cy...

Page 38: ...arried out prior to returning the compressor to the suppliers Only electric heating of the compressor body can be employed to accelerate this process When oil is drained from a system it must be carried out safely Labeling Decommissioned Equipment Equipment must be labelled stating that it has been de commissioned and emptied of refrigerant The label must be dated and signed Ensure that there are ...

Page 39: ...tion repairs Always recover all refrigerant prior to any system repairs Failure to do so may result in system over pressurization and rupture Follow the guidelines in Recovering Refrigerant p 37 Turn off power to the unit at the service disconnect switch unless you are performing tests that require power With power and controls energized the unit could begin operating automatically at any time Haz...

Page 40: ... condensate pump should be inspected semi annually and cleaned Ensure that the float works freely Wipe the float with a wet cloth and detergent to remove dirt Clean the tank bottom Check that the discharge line is open and water can pass through it freely Humidifier The optional humidifier s steam cylinder has a limited lifetime and must be replaced periodically Because water conditions and humidi...

Page 41: ...ails to Start a Power failure Check main voltage power source input cable b Control transformer circuit breaker tripped Check for short circuit or ground fault if none reset circuit breaker c Defective contactor Repair or replace Repair or replace d Thermal overload tripped Reset overload and check amperage of motor Compare to setting on overload and adjust to FLA All direct drive motors are inter...

Page 42: ...er strainer feels cold Replace with new drier strainer d Reduced airflow Check belt tension filters and clear evaporator coil of debris Compressor Short Cycles a Low line voltage causing compressor to overheat Check power source for cause of low line voltage b Dirty or iced over evaporator coil Defrost and or clean coil c Reduced airflow when applicable Check filter and belt tension d Lack of refr...

Page 43: ...electrical connections d Humidifier fuses are blown Check for overcurrent by the humidifier electrodes Drain water from tank and refill Replace fuses e Relative humidity is above setpoint Adjust humidistat setpoint f Yellow status LED is flashing Consult humidifier manual g Water conductivity is too low Add a teaspoon of table salt to the water through the top of the cylinder Typically only requir...

Page 44: ... Refrigerant Piping When replacing components within the cabinet of the unit the following consumable materials are recommended 1 Use Sil Fos alloy for copper to copper piping discharge or suction line repairs 2 Use silver solder Stay Silv 45 and flux on copper to brass or copper to steel repairs General Common Repairs Component Replacement Compressor Failure The compressor is the most important c...

Page 45: ...aned using the suction line filter drier method 2 If your unit is equipped with an E controller turn the A C unit off by pressing and holding the Enter key 3 Turnoffpowertotheunitatthemainpowerdisconnect switch 4 Remove the burned out compressor and install the new compressor 5 Install a suction line filter drier designed for acid removal 6 Remove the liquid line drier and install the appropriate ...

Page 46: ... the filter is accessed through an access panel labeled FILTER ACCESS Remove the access panel and old filter Ensuring directional airflow arrowson filter arecorrect insert the new filter and replace the access panel Product Support Product Support provides aftermarket technical and field support warranty authorization and part sales to contractors and end users Factory authorized services are avai...

Page 47: ...art s is conducted and if the part is found to have a manufacturing defect a credit will be issued When returning defective part s complete the Return Material Authorization Tag and the address label provided with the replacement part For prompt processing please affix the RMA in a prominent place on the external packaging of the returned part Obtaining Spare Replacement Parts Maintaining a recomm...

Page 48: ...ass Fail N A Inspect low voltage connections Pass Fail N A Inspect relays and contactors for serviceability i e pitted contacts weak coils Pass Fail N A Note The following should be performed by Trained Service Personnel only Table 14 Record supply voltage L1 GND L2 GND L3 GND L1 L2 L2 L3 L1 L3 Table 15 Unit operation Verify Control Device Operation Pass Fail N A Verify Customer Setpoints Pass Fai...

Page 49: ... L2 L3 Compressor 2 L1 L2 L3 Table 20 Record compressor amp draw Circuit 1 Discharge Pressure Suction Pressure Discharge Line Temp Suction Line Temp Liquid Line Temp Subcooling Superheat EW LWT Circuit 1 Discharge Pressure Suction Pressure Discharge Line Temp Suction Line Temp Liquid Line Temp Subcooling Superheat EW LWT Table 21 Check humidifier operation Check electrical connections Yes No N A C...

Page 50: ...er overloads for damage Yes No N A Table 24 Record heater s amp draw Heater 1 L1 L2 L3 Heater 2 L1 L2 L3 Heater 3 L1 L2 L3 Heater 4 L1 L2 L3 Table 25 Site recommendations 1 2 3 4 5 Table 26 Final verification Technician Signature Date QA Verification Date Appendix A TR OHS Preventive Maintenance Inspection Checklist 50 AH SVX008C EN ...

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Page 52: ...e are committed to using environmentally conscious print practices Trane by Trane Technologies NYSE TT a global climate innovator creates comfortable energy efficient indoor environments for commercial and residential applications For more information please visit trane com or tranetechnologies com AH SVX008C EN 30 Dec 2020 Supersedes AH SVX008B EN Apr 2020 ...

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