Technical data

If pumps discharge through the chiller, the strainer may
be located upstream from pumps to protect both pump
and chiller. (Piping between strainer, pump and chiller
must be very carefully cleaned before start-up.) If
pumps are remotely installed from chiller, strainers
should be located directly upstream of the chiller.
4.10 Water Treatment
The unit performance given in the Design Guide is
based on a fouling factor of 0.044 m²°C/kW (0.00025
ft²hr °F/Btu). Dirt, scale, grease and certain types of
water treatment will adversely affect the heat exchanger
surfaces and therefore unit performance. Foreign
matter in the water system(s) can increase the heat
exchanger pressure drop, reducing the flow rate and
causing potential damage to the heat exchanger tubes.
Aerated, brackish or salt water is not recommended for
use in the water system(s). York recommend that a
water treatment specialist is consulted to determine that
the proposed water composition will not affect the
evaporator materials of carbon steel and copper. The
pH value of the water flowing through the heat
exchangers must be kept between 7 and 8.5.
4.11 Glycol Solutions
For unit operation with chilled liquid temperatures
leaving the cooler at below 4°C, glycol solutions should
be used to help prevent freezing. Section 9, gives
recommended solution strength with water, as a
percentage by weight, for the most common types of
glycol. It is important to check glycol concentration
regularly to ensure adequate concentration and avoid
possible freeze-up in the cooler.
When using glycol solutions, pressure drops
are higher than with water. Special care must
be taken not to exceed the maximum pressure
drop allowed.
4.12 Condenser Water Circuit
For proper operation of the unit, condenser refrigerant
pressure must be maintained above cooler pressure. If
operating conditions will fulfill this requirement, no
attempt should be made to control condenser water
temperature by means of automatic valves, cycling of
the cooling tower fan or other means, since chillers are
designed to function satisfactorily and efficiently when
condenser water is allowed to seek its own temperature
level at reduced loads and off-peak seasons of the year.
However, if entering condenser water temperature can
go below the required minimum, condenser water
temperature must be maintained equal to or slightly
higher than the required minimum. Refer to Figure 4.3
for a typical water piping schematic.
4-4 035L02381-GB0
Figure 4.3 Typical Piping Arrangement