United CoolAir VariCool EZ-Fit Series, Installation, Operation And Maintenance Manual

Installation, Operation and Maintenance Manual

VariCool EZ-Fit

36

Subject to change without notice.

Start-Up Procedures 

(R-410a Systems)

1� 

Start up must be performed by a qualified HVAC 

Technician

2� 

Make certain that all power is disconnected at the main 

power circuit breaker or service disconnect before 

starting any of this procedure

3� 

Check all electrical screw terminals and wiring lugs 

for tightness internal to the equipment Components 

may have loosened due to vibration during transit 

or handling Verify that the main power block lug 

connections made in the field are tight and secure

4� 

Confirm that the voltage rating of the equipment data 

tag coincides with the power that will be delivered to 

the unit

5� 

Verify that the circuit protection for the unit satisfies 

Local and National Codes according to the unit data 

tag Minimum Circuit Ampacity (MCA) and Maximum 

Fuse Size (MFS)

6� 

Leak check the refrigerant system While the unit was 

leak checked at the factory, leaks can develop during 

transit and / or handling

7� 

Confirm that the unit condensate has been adequately 

trapped and taken to a suitable point for disposal

8� 

Verify that the filters are in place, clean and usable

9� 

Apply power to the unit Switch the circuit breaker or 

field supplied electrical service disconnect switch to the 

on position

NOTE: If the unit has crankcase heaters and the surrounding 

ambient is 70˚ F or lower, let the compressors sit for 

approximately 24 hours before proceeding�

10� 

Record the voltage at the unit terminals

11� 

On the wall controller, navigate to the system enables 

menu Set the compressor to OFF Set the system  

ON/OFF menu to the ON position

12� 

Verify that the evaporator blower(s) are rotating in the 

correct direction (three phase units only)

NOTE: If the evaporator blower motor runs backwards, 

shut off all power to the unit. Switch any two of the 

incoming power leads at the unit main power terminal 

block. The unit has been wired and phased properly 

at the factory� DO NOT change any factory wiring to 

correct for a phase problem�

NOTE: Before conducting the following start up sections 

connect a refrigerant gauge set to the unit Schrader 

connections� Install temperature sensors or probes to 

record the appropriate refrigerant line temperatures�

13� 

Set the wall controller to a temperature set point 

approximately 5˚ lower than the entering air 

temperature This should energize the compressor(s)

NOTE: Dependent upon the options and/or the thermostat, 

there may be a delay for the compressor(s) operation�

14� 

While waiting for the compressor(s) to stabilize, record 

the External Static Pressure (ESP) for the evaporator 

blower

NOTE: Make sure all the unit access panels are in place when 

taking these readings.

WARNING

HEAT EXCHANGER FREEZE RISK:

Heat Exchanger will fail if operated at or 

near  the  freezing  point  of  water/glycol 

mixture
The following precautions must be taken:

•  At startup, fluid side must be started 

first

•  At shutdown, refrigerant side must be 

shut down first

•  Fluid side outlet must have temperature 

monitoring and emergency shutdown 

equipment in case temperature 

approaches too close to the freezing 

point

15� 

Verify that the incoming water / fluid pressure does not 

exceed the rating for the water / fluid control valves

16� 

Verify that the unit piping and heat exchangers will not 

be subjected to freezing conditions

17� 

Confirm that no joints are leaking in the cooling fluid 

circuit(s)

18� 

Document the type of fluid being used as the cooling 

medium If glycol is being used, make sure the mixture 

is adequate for any low ambient conditions that may be 

possible

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