Refrigerant Charging Procedures - Trane TR-OHS RCU Series Installation, Operation And Maintenance Manual

Installation
4. If evacuation is not possible in the system below 150
microns, close the vacuum pump isolation valve and
perform a rate-of-rise test by observing the standing
pressure over time. If the pressure rises slowly (up to
200 microns in 15 minutes) it indicates moisture is in
the system that still needs to be boiled off.
If the pressure rises rapidly up to atmospheric pressure
(more than 50 microns per minute) it indicates a leak
that wasn't detected during
troubleshoot the entire system for leaks and repair
them. Then begin the initial evacuation process again
starting at Step 3.
5. If no leaks are detected after the initial vacuum, release
the vacuum and pressurize the system with 2-3 lbs of
dry nitrogen. Allow the 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 macrons or less. Close the vacuum pump
isolation valve and pressurize the system again with
dry nitrogen and allow the system to stand for two
hours as in Step 5.
7. After two hours release the pressure. Turn on the
vacuum pump and complete the process of evacuating
the system, this time with a goal of achieving a 500
micron vacuum or less. Close the vacuum pump
isolation valve. If the vacuum holds at 500 microns or
lower for at least 2 hours with no significant rise in
pressure, then the system is ready to charge.
8. Replace the Schrader valve cores if removed in the
evacuation steps. Introduce the refrigerant charge
through the Schrader valves.

Refrigerant Charging Procedures

NOTICE
Equipment Damage!
POE oil is used in systems with R407C refrigerant. POE
oil quickly absorbs moisture when exposed to air. High
POE oil moisture levels react with refrigerant to form
acid which results in system contamination. Keep the
entire system sealed as much as possible and minimize
exposure of the POE oil to outside air.
16
Step 2. In this case
WARNING
Confined Space Hazards!
Failure to follow instructions below could result in
death or serious injury. Do not work in confined spaces
where refrigerant or other hazardous, toxic or
flammable gas may be leaking. Refrigerant or other
gases could displace available oxygen to breathe,
causing possible asphyxiation or other serious health
risks. Some gases may be flammable and or explosive.
If a leak in such spaces is detected, evacuate the area
immediately and contact the proper rescue or response
authority.
Note: Refrigerant charging must be performed by a
qualified air conditioning technician. Trane
recommends using the services of our Field
Service Department to assist in start-up and
commissioning.
We have assembled a highly qualified team of
experienced industry professionals who provide expert
start-up services anywhere in the world. They will ensure
the equipment is correctly installed and is operating
properly. This will help to ensure the unit provides years of
trouble-free service while operating at its highest
efficiency. They will also enter the necessary Information
on the Warranty Registration and Start-up Checklist and
ensure it is filed with Trane for the warranty protection.
Estimating Refrigerant Charge
When charging a system with R407C refrigerant it will be
necessary to weigh the refrigerant. Calculate the amount
of refrigerant needed by adding the amount of refrigerant
required for the A/C unit (shown in the A/C unit IOM
provided separately) plus the refrigerant for the RCU
(Table 5) plus the refrigerant piping
Table 5 may be used to estimate the amount of R407C
refrigerant needed (in lb) to charge RCUs by model
number.
The values shown in Table 5
final refrigerant charge weight depends on site-specific
conditions.
Example: Estimate the amount of refrigerant required for
a system using R407C refrigerant consisting of a 5 ton
A/C unit connected with a 1/2 inch x 30 equivalent ft liquid
line and 7/8 inch x 30 equivalent ft discharge line to a RCU-
060 -30°F condensing unit with flooded head pressure
control and receiver.
A/C Unit = 5.2 lb
+ RCU w/Flooded HP Control = 18.8 lb
+ 1/2 in. Liquid Line- 30 × 6.51
+ 7/8 in. Suction Line- 30 × 0.57
= Total Estimated Refrigerant Charge = 26.124 lb
(Round off to the nearest lb = 26 lb)
(Table 6).
are estimated weights. The
= 1.953 lb
100
= 0.171 lb
100
SS-SVX004C-EN