Water Treatment; Fig. 6 - Pipework Arrangement - York YCAS Series Installation Operation & Maintenance

Installation
Pipework and fi ttings must be separately supported
to prevent any loading on the evaporator. Flexible
con nec tions are recommended which will also minimize
transmission of vibrations to the building. Flexible
connections must be used if the unit is mounted on
anti-vibration mounts as some movement of the unit
can be ex pect ed in normal operation.
Pipework and fi ttings immediately next to the evaporator
should be readily de-mountable to enable cleaning
be fore operation, and to facilitate visual inspection of
the exchanger nozzles.
The evaporator must be protected by a strainer,
pref er a bly of 30 mesh, fi tted as close as possible
to the liq uid inlet connection, and provided with a
means of local isolation.
The evaporator must not be exposed to fl ushing velocities
or debris released during fl ushing. It is recommended
that a suitably sized by-pass and valve arrangement is
in stalled to allow fl ushing of the pipework system. The
by-pass can be used during maintenance to isolate the
heat exchanger without disrupting fl ow to other units.
Thermometer and pressure gauge connections should
be provided on the inlet and outlet connections of each
evaporator.
Drain and air vent connections should be provided at all
low and high points in the pipework to permit drain age
of the system and to vent any air in the pipes.
Liquid systems at risk of freezing, due to low ambient
temperatures, should be protected using insulation and
heater tape and/or a suitable glycol solution. The liquid
pump(s) must also be used to ensure liquid is cir cu lat ed
when the ambient temperature approaches freez ing point.
Insulation should also be installed around the evaporator
noz zles. Heater tape of 21 watts per meter un der the
insulation is recommended, supplied in de pen dent ly and
controlled by an ambient temperature ther mo stat set to
switch on at 37°F (21°C) above the freez ing tem per a ture
of the liquid.
The liquid circulation pump must be controlled by the
unit. This will ensure that when the liquid temperature
falls within 3° or 5°F (2° or 3°C) of freez ing, the pump
will start.
The evaporator is protected by heater mats un der the
in su la tion which are supplied from the unit con trol
system pow er supply. Dur ing risk of freezing the
control sys tem should be powered on to provide the
freeze pro tec tion func tion un less the liq uid systems
have been drained.
30
Any debris left in the water pipework
be tween the strain er and evaporator
could cause se ri ous damage to the
tubes in the evaporator and must be
avoided. The in stall er/user must also
en sure that the quality of the wa ter
in cir cu la tion is ad e quate, with out
any dis solved gas es which can cause
ox i da tion of steel parts within the
evaporator.

WATER TREATMENT

The unit performance given in the Design Guide is based
on a fouling factor of 0.00025 ft
°C/kW). Dirt, scale, grease and cer tain types of water
treat ment will ad verse ly affect the heat ex chang er
sur fac es and there fore unit per for mance. Foreign mat ter
in the water system(s) can increase the heat ex chang er
pres sure drop, reducing the flow rate and caus ing
po ten tial damage to the heat exchanger tubes.
Aerated, brackish or salt water is not recommended for
use in the water system(s). YORK recommends that
a wa ter treatment specialist is consulted to determine
the proposed water composition will not affect the
evap o ra tor materials of carbon steel and copper. The
pH val ue of the water fl owing through the evaporator
must be kept be tween 7 and 8.5.
Isolating Valve - Normally Open
Isolating Valve - Normally Closed
Flow Regulating Valve
Flow Measurement Device
Strainer
Pressure Tapping
Flow Switch
Flanged Connection
Pipework
FIG. 6 – PIPEWORK ARRANGEMENT
FORM 201.19-NM8 (804)
2
hr°F/Btu (0.044m2/hr
Water
Out
Water
In
LD04739
YORK INTERNATIONAL