Installation and Maintenance Manual

Installation—Piping
UV-SVN03F-EN 25
the condensing unit installation and wiring manuals which
are shipped with the condensing unit.
Note: The ETL listing mark applied to a unit ventilator
does not apply to any associated refrigerant
condensing unit.
Refrigerant Piping
Unit ventilators with direct expansion cooling contain a
nitrogen holding charge in the evaporator coils.
Connections are “pinched-off” at the factory.
To connect the condensing unit lines, cut off the stubouts
and swage. The condensing unit lines can then be brought
into the swage and brazed. Trane recommends the use of
nitrogen purge when brazing refrigerant lines to prevent
formation of oxides in the lines.
Install the refrigerant suction and liquid lines as described
in the condensing unit installation instructions. The TXV is
factory installed on the unit ventilator. Piping should be
run straight out through the back of the unit. Access piping
knockouts are located in the rear panels of the unit, as
shown “Dimensions and Weights,” p. 11.
Recommended refrigerant line connections for various
unit combinations are given in Table 8, p. 24. Typical
Superheat Charging Charts are shown in the Trane Service
Facts found in the condensing unit section manual.
Refrigerant charge weights can also be determined with
your local Trane sales engineer using a valid Trane
Selection Program.
Steam Piping
When air, water or another product is heated, the
temperature or heat transfer rate can be regulated by a
modulating steam pressure control valve. Since pressure
and temperature do not vary at the same rate as load, the
steam trap capacity, which is determined by the pressure
differential between the trap inlet and outlet, may be
adequate at full load, but not some lesser load.
There are detailed methods for determining condensate
load under various operating conditions. However, in
most cases this is not necessary if the coils are piped as
shown in Figure 13. Follow the procedure documented in
the ASHRAE Systems Handbook, Steam Systems.
Modulating Water Valves (Option)
The actuator on the valve is a 24V, 3-point floating valve.
The actuator can be easily removed from the valve body
by pressing in on the locking tab and rotating the actuator
45° counter-clockwise (see Figure 14). The 2-way valves
are bi-directional flow; the 3-way valves can be mixing or
diverting (see Figure 15, p. 26).
Note: The actuator must be removed if soldering is being
conducted near the valve. High heat may cause
damage to the actuator’s plastic body/
mechanisms.
WARNING
Hazard of Explosion and Deadly Gases!
Never solder, braze or weld on refrigerant lines or any
unit components that are above atmospheric pressure
or where refrigerant may be present. Always remove
refrigerant by following the guidelines established by
the EPA Federal Clean Air Act or other state or local
codes as appropriate. After refrigerant removal, use dry
nitrogen to bring system back to atmospheric pressure
before opening system for repairs. Mixtures of
refrigerants and air under pressure may become
combustible in the presence of an ignition source
leading to an explosion. Excessive heat from soldering,
brazing or welding with refrigerant vapors present can
form highly toxic gases and extremely corrosive acids.
Failure to follow all proper safe refrigerant handling
practices could result in death or serious injury.
Figure 13. Steam piping
Figure 14. Remove modulating valve actuator by
pressing in tab (inset) and turning actuator
45° counterclockwise
Vacuum Equalizer
H= 12"
minimum
F&T Trap
See text for sizing
Gravity flow to
vented receiver
Coil
To Condensate
return
Temp. Regulating Valve
UV-SVN03_.book Page 25 Thursday, January 24, 2013 5:27 PM