Carrier 380B - Manual (Page 8)

Table 6 — Service Data
Refrigerant Charging
— The 38QB units contain
correct operating charge for complete system when
connected to28HQ,VQ,40QB or 40AQ indoor units
with 25 ft (7.6 m) of tubing of recommended diam­
eter. Charge adjustment is required on other sys­
tems. Adjust system charge for refrigerant line
lengths and diameters that differ from 25 ft (7.6 m)
and 3/8 in. (9.53 mm) OD (liquid line), respectively,
using refrigerant weights below. Twenty-five ft
(7.6-m), 3/8-in. (9.53-mm) OD tubing contains
14.4 oz (.4 kg) of R-22. Add R-22 charge to system
if liquid line is over 25 ft (7.6 m); remove charge
if liquid line is shorter than 25 ft (7.6 m).
When recharging is necessary during heating or
cooling season, weigh in total charge indicated in
Table 6. (Charge must be weighed in during heating
season.) Remove any refrigerant remaining in
system before recharging. If system has lost com­
plete charge, triple-evacuate system to 5000 microns
(29.7 in. [100.5 kPa] vacuum) before recharging.
Service port connections are provided on liquid and
suction line service valves for evacuation and charg­
ing. (See Fig. 6 for correct service port location
on cooling and heating cycles.) Dial-a-charge
charging cylinder is an accurate device used to re­
charge systems by weight. These cylinders are avail­
able at refrigeration supply firms.
To check and/or adjust charging during cooling
season, use correct Cooling Cycle Charging Chart
(Fig. 8, 10, 12, 14, 16) and follow Charging Chart
Method below. The charging chart may also be used
as an alternate method of recharging system.
To check system operation during heating cycle,
use correct Heating Cycle Operation Check Chart
(Fig. 9, 11, 13, 15, 17). These charts indicate
whether a correct relationship exists between system
operating pressures and air temperatures entering
indoor and outdoor units. If pressure and tempera­
ture lines do not intersect on chart, the system
refrigerant charge may not be correct or other
system abnormalities may exist. Do not use Opera­
tion Check Charts to adjust refrigerant charge.
Weigh charge into system.
LIQUID LINE
DIAM (in.)
OUNCES OF R-22/FT LENGTH
OF LIQUID LINE
3/8 58
5/16 36
1/4 .21
0 AV (•<*
M ' '
tm
urn ,08
UNIT38QB
I
018
1 1
030
1
036
1
042
R-22 CHG (lb)
i
m Ì 4,5
3,04
1
72 1 .7,3 ! 7,8
1
8,5
REFRIG CONTROL | AccuRater™' (Bypass Type)
FAN
i 1
Cfin 1800 i 3000
t/4 1 Ml#
Rpm
1
107S
Diam (in.) 14-3/4 1 , 20
\ 1 ' ' '
Fig. 6 — 38QB Refrigerant Flow Diagrams
COOLING CYCLE CHARGING CHART
METHOD
1. Operate unit a minimum of 10 minutes before
checking charge, and after each charge
adjustment.
2. Measure suction pressure by attaching a gage to
outdoor unit suction service port. (See Fig. 6
for correct service port location on cooling cycle.)
3. Measure outdoor (coil inlet) air dry-bulb tem­
perature with service thermometer.
4. Using a sling psychrometer, measure wet-bulb
temperature of air entering indoor unit.
5. Refer to correct Charging Chart. Locate on
curves where outdoor air dry-bulb and indoor
air wet-bulb temperature lines intersect.