Split System Piping - Trane VUV Installation, Operation And Maintenance Manual

Split System Piping

The following refrigerant piping and interconnecting wiring
instructions apply to unit ventilators with direct expansion type
cooling coils used in conjunction with air-cooled condensing
units. Reference must also be made to the condensing unit
installation and wiring manuals which are shipped with the
condensing unit.
Note: The UL listing mark applied to a unit ventilator does not
apply to any associated refrigerant condensing unit.
Refrigerant Piping
WARNING
Explosion Hazard and Deadly Gases!
Failure to follow all proper safe refrigerant handling
practices could result in death or serious injury.
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.
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
and Weights," p. 11.
Recommended refrigerant line connections for various unit
combinations are given in Table 10, p.
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.
UV-SVX005G-EN
"Dimensions
23. Typical Superheat
Coil Piping and Connections
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 20, p. 27. Follow the procedure documented in the
ASHRAE Systems Handbook, Steam Systems.
Figure 20. Steam piping
Temp. regulating valve
Coil
To condensate
return
F and T trap
Modulating Steam Valves
An optional 2-way modulating steam valve can be selected
with steam coils. The valve is field installed. When plumbing
the valve, the AB port must be connected to the coil.
Figure 21. Belimo steam schematic
COIL
Note: The actuator must be mounted between 0 and 45
degrees from horizontal. Do not install with actuator
below pipe.
H= 12 in.
minimum
Vacuum equalizer
Gravity flow to
vented receiver
Supply
AB A
Return
27