YZ Engineering Guide
Form: 161.01-EG1 (0618)
17
Application Data
The following is a guide to the application of YZ chillers to ensure reliable operation. While this guide is directed
towards normal, water-chilling applications, a Johnson Controls sales engineer can provide complete
recommendations on other types of applications.
LOCATION
YZ chillers are virtually vibration free and may generally be located at any level in a building where the construction will
support the total system operating weight.
The unit site must be a floor, mounting pad or foundation which is level within 6.5 mm (1/4") and capable of supporting
the operating weight of the unit.
Sufficient clearance to permit normal service and maintenance work should be provided all around and above the unit.
Additional space should be provided at one end of the unit to permit cleaning of evaporator and condenser tubes as
required. A doorway or other properly located opening may be used if convenient.
The chiller should be installed in an indoor location where temperatures range from 4.4°C to 40.0°C (40°F to 104°F).
The dew point temperature in the equipment room must be below the entering condenser water temperature to prevent
condensing water vapor inside of the VSD. Other areas susceptible to water vapor condensate are outside of the
condenser shell and condenser waterboxes. Example applications include cooling condenser water using chilled water,
wells, river, or other low temperature fluids.
Refrigerant Relief Piping
-
Each chiller is equipped with dual pressure relief valves on the condenser and two dual relief
valves on the evaporator, or two single relief valves on the evaporator if the optional refrigerant isolation valves are
ordered. The dual relief valves on the condenser are redundant and allow changing of either valve while the unit is fully
charged. The purpose of the relief valves is to quickly relieve excess pressure of the refrigerant charge, as a safety
precaution in the event of an emergency such as a fire. They are set to relieve at an internal pressure as noted on the
pressure vessel data plate, and are provided in accordance with local pressure vessel codes.
Sized to the requirements of applicable codes, a vent line must run from the relief device to the outside of the building.
This refrigerant relief piping must include a cleanable, vertical leg dirt trap to catch vent-stack condensation. Vent piping
must be arranged to avoid imposing a strain on the relief connection and should include one flexible connection.
Sound and Vibration Considerations
- A YZ chiller is not a source of objectionable vibration in most air conditioning
applications. Standard neoprene isolation mounts are available with each unit to reduce vibration transmission. Optional
level-adjusting spring isolator assemblies designed for 25.4 mm (1") static deflection are also available for further
isolation. YZ chiller sound pressure level ratings will be provided upon request. Control of sound and vibration
transmission must be taken into account in the equipment room construction as well as in the selection and installation
of the equipment.
Thermal Insulation
-
The chiller’s cold surfaces should be insulated with a vapor barrier insulation sufficient to prevent
condensation. As an option, a chiller can be factory-insulated. This insulation will normally prevent condensation in
environments with dry bulb temperatures of 10.0°C to 32.2°C (50°F to 90°F) and relative humidity up to 75% [19 mm
(3/4") thickness]
, 85% [25.4 mm (1”) thickness], or 90% [38 mm (1.5") thickness]. It is intended for a chiller installed
indoors and, therefore, no protective covering of the insulation is usually required. If insulation is applied to the
waterboxes at the job site, it must be removable to permit access to the tubes for routine maintenance.
