Emerson AE4-1395 Manuel D’Utilisation

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© 2012 Emerson Climate Technologies, Inc.

Printed in the U.S.A.

Application Engineering

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7.  Using the appropriate lifting devices, carefully 

remove the compressor from the system.

The following steps should be followed to install the digital 

compressor into the system.

1.  Before removing the rubber plugs, install the 

compressor in the unit on the mounting grommets 

using the appropriate lifting devices.

2.  Install the compressor mounting bolts.
3.  Connect the suction and discharge lines using 

standard brazing practices.

4.  If the compressor has an external modulation valve 

and tubing (3 to 7.5 ton only) refer to 

Figure 8 for the 

correct valve orientation and position. Wrap a wet 

rag around the valve and complete the assembly 

by brazing the valve and tubing into place.

5.  Check for leaks using nitrogen with a properly sized 

regulating and relief valve.

6.  Connect conduits and wiring to the compressor. 

Inspect and/or replace the contactor. If the 

compressor is 1-phase, install the correct run 

capacitor.

In the system with a digital compressor, the refrigerant 

flow control valve is required to control flow across a wide

range of flow rates and varying pressure differentials.

Most balanced port thermostatic expansion valves can 

control flow down to about 40% of their rated capacity.

Excessive hunting and loss of superheat control can 

result when asking a thermostatic expansion valve to 

operate outside of its design range. For this reason, 

the expansion device needs to be evaluated to ensure 

reliable operation over the expected operating range. 

Limiting the minimum compressor modulation rate to 

a value that the expansion valve can tolerate should 

be considered. Electronic expansion valves should be 

considered if modulation over the entire range of the 

compressor’s modulation range is anticipated.

For the highest level of energy savings, comfort, and 

efficiency the variable capacity system should be capable

of  varying  the  air  flow.  Variable  frequency  drives  and

tapped  blowers  are  two  means  of  reducing  air  flow.

Reducing  air  flow  in  humid  or  maritime  climates  is

important to maintain coil temperatures low enough to 

remove latent heat. In desert and arid climates, because 

of low or no latent loads, air flow is less critical.
The controls required for variable air flow are not provided

by Emerson so the contractor may need to consult with 

controls experts in this field.

Modulating the condenser air flow is not critical to the

success of the application. For the highest level of energy 

savings, condenser air flow will be reduced based on the

compressor modulation rate, condensing temperature, 

ambient temperature, etc.

The preferred modulation control for retrofit applications

is the Commercial Comfort Controller. This controller is a 

closed loop controller that is installed in the conditioned 

space. The controller measures the space temperature 

and through an algorithm in the controller, controls the 

modulation of the digital scroll. The controller can be 

positioned up to 300 feet from the compressor/unit, is 

configurable for roof top unit or heat pump, and is wired

like a commercial room thermostat. For more information 

on the Commercial Comfort Controller please refer to 

AE8-1393.

 

3 To 7.5 Ton Modulation Valve Brazing Procedure
The external modulation valve is purchased and shipped 

separately from the 3 to 7.5 ton digital scroll. Therefore, 

assembly is required in the OEM manufacturing plant. 

Figure 8 illustrates the correct position and orientation 

of the modulation valve. Please note the direction of the 

arrow on the valve, it must point to suction.

When brazing the modulation valve into the system, 

the valve must be wrapped with a wet rag to help keep 

the valve cool. The torch flame must be directed away

from the valve and the brazing operation should be 

done quickly so the valve isn't overheated. The brazing 

operation should be performed with a nitrogen purge to 

prevent the build-up of copper oxide. The solenoid coil 

should be installed after the brazing operation, so the 

leads are kept away from the brazing operation and the 

wet rag is able to fully contact the valve body.

Pressure Testing
The pressure used on the OEM assembly line to meet 

the UL burst pressure requirement cannot be higher 

than

 400 psig (27.6 bar) for R-407C & R-22 and 475 

psig (32.8 bar) for R-410A. Higher pressure may result 

in permanent deformation of the compressor shell and 

possibly cause misalignment or bottom cover distortion.