Unit installation

803 C – 01/05 A – pag. 5/17
• When using a cooling tower, add glycol solution to the chilled water system. Freeze point should be
approximately 6°C below minimum design ambient temperature.
• Insulate field water piping, especially on the chilled water side.
Note: Freeze damage is not considered a warranty failure and is not the responsibility of McQuay International.
Water piping
Due to the variety of piping practices, it is advisable to follow the recommendations of local authorities. They can
supply the installer with the proper building and safety codes required for a safe and proper installation.
Basically, the piping should be designed with a minimum number of bends and changes in elevation to keep
system cost down and performance up. It should contain:
1. Vibration eliminators to reduce vibration and noise transmission to the building.
2. Shut-off valves to isolate the unit from the piping system during unit servicing.
3. Manual or automatic air vent valves at the high points of the system. Drains at the low parts in the system. The
evaporator should not be the highest point in the piping system.
4. Some means of maintaining adequate system water pressure (e.g., expansion tank or regulating valve).
5. Water temperature and pressure indicators located at the unit to aid in unit servicing.
6. A strainer or some means of removing foreign matter from the water before it enters the pump. The strainer
should be placed far enough upstream to prevent cavitation at the pump inlet (consult pump manufacturer for
recommendations). The use of a strainer will prolong pump life and help maintain high system performance
levels.
7. A strainer should also be placed in the supply water line just prior to the inlet of the evaporator. This will aid in
preventing foreign material from entering and decreasing the performance of the evaporator.
8. If the unit is used as a replacement chiller on a previously existing piping system, the system should be
thoroughly flushed prior to unit installation and then regular chilled water analysis and chemical water treatment
is recommended immediately at equipment start-up.
9. In the event glycol is added to the water system, as an afterthought for freeze protection, recognize that the
refrigerant suction pressure will be lower, cooling performance less, and water side pressure drop greater.
System safety devices such as freeze protection and low pressure protection must be reset.
Prior to insulating the piping and filling the system, a preliminary leak check should be made.
Chilled Water Thermostat
The PFS water-cooled chiller is equipped with the MicroTech II leaving water controller. Be careful when working
around the unit to avoid damaging lead wires and sensor cables. Check lead wires before running the unit. Avoid
rubbing the lead wires on the frame or other components. Verify the lead wires are firmly anchored. If the sensor is
removed from the well for servicing, do not wipe off the heat conducting compound supplied in the well.
Refrigerant Charge
All units are designed for use with HFC-134a and are shipped with a full operating charge. The operating charge
for each unit is shown in the Physical Data Table.
Flow Switch
A water flow switch must be mounted in either the entering or leaving water line to insure that there will be
adequate water flow to the evaporator before the unit can start. This will safeguard against slugging the
compressors on start-up. It also serves to shut down the unit in the event that water flow is interrupted to guard
against evaporator freeze-up. A flow switch is available from McQuay and it is a "paddle" type switch and
adaptable to any pipe size from 1" (25mm) to 8" (203mm) nominal.
Certain minimum flow rates are required to close the switch and are listed in Table 1.