Carrier 30HH - Manual (Page 22)

30HH,HJ
INSTALLATION
glycols or brines are to be cooled. The adjust­
ment tolerance is commonly j- 1 F.
DAMAGE DUE TO THE FREEZING OF A CHILL -
ER IS NOT COVERED BY THE WARRANTY.
The safety thermostat bulb is located in the
leaving chilled water piping stubout.
IMPORTANT: This thermostat should
be checked at the time of installation
and at least once every season. If the
bulb is damaged in handling, its cali­
bration may be off.
To check the safety thermostat:
1. Place the thermal bulb in a vacuum bottle
filled with water and add crushed ice.
NOTE: This is an insert type bulb. On
earlier units, removal opens water sys-
except on 30HH,HJ045 thru 065 units
which use a sealed well. Later units
all use a sealed well.
2. Stir the contents with a thermometer and
note the temperature at which safety thermo­
stat cuts out.
3. Reset the safety thermostat if necessary. To
set the control, use screwdriver in slot and
rotate
dial until the desired temperature at
which compressor is to stop is directly under
indicator "B”.
To recalibrate the safety thermostat;
1. Measure the temperature as close to the bulb
as possible, immediately after the compres­
sor stops.
2. Break the painted seal between the dial and
the adjusting plate with a knife.
3. Carefully loosen the two dial screws. Be care­
ful not to turn the brass cylinder below the
dial during this or any of the following oper­
ations.
4. Turn the dial ONLY so that the fixed indica­
tor points to thè temperature measured at
step 1.
5. Carefully tighten the dial screws.
I ‘-f
FIXED IMDICATOR
ADJUSTING SLOT
Fig. 27 - Safety Thermostat
High and Low Pressure Controls
Pressure control settings are shown in Table 8.
The 30HJ high pressure control settings are suit­
able for use with either air-cooled or evaporative
condensers. The control setting (Table 8) is a
fixed setting and is nonadjustable.
Check the high pressure switch setting by slowly
closing the discharge shut-off valve. The com­
pressor should shut down when the discharge
pressure reaches 260 or 355 psi (as required)
and start up when the pressure drops to 210, or
255 psi (as required).
The 30HH high pressure switches are adjustable
and equipped with a stop to prevent field setting
above 280 lbs.
To check the low pressure switch, close the
suction shut-off valve and allow the compressor
to pump down. The compressor should cut out
when the suction pressure falls to 46 psig, and
automatically
start up again when the suction
pressure builds up to 83 psig.
Both sides should be checked at startup and at
least once a year thereafter.
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