10
Evacuation
All new installations must be evacuated to a deep vacuum in order that all noncondensible gases
and moisture are removed prior to charging the system. Air in a system causes high condensing
pressure, which increases power consumption and reduces performance. The presence of moisture
in a system can render it inoperable in a very short time. Proper evacuation assures a dry, uncontaminated
system. Here is the recommended evacuation procedure:
1.Connect vacuum pump to both liquid and suction valve service ports.
2.Evacuate the interconnecting tubing and indoor coil to 500 microns or less for a minimum
of 30 minutes. Close the valve to the vacuum pump and wait 15 minutes. Vacuum should
not rise above 800 microns. If unable to obtain 500 microns, or vacuum rises above 800
microns over 15 minutes period, discontinue evacuation, pressurize and check for leaks.
Repair any leaks found and repeat the step 2.
3.Close valve to the vacuum pump and stop pump.
4.When sure of a tight, well evacuated system, charge with refrigerant.
Charging the System
(For systems with capillary tube or fixed orifice metering device)
Before checking the system charge, make sure that the outdoor unit and indoor coil must be an
approved match per the unit specification. The indoor conditions should be within 2 F of the desired
comfort conditions.
! WARNING
-
Do not vent refrigerant to the atmosphere
! It is a violation of federal law to do
so. If the refrigerant needs to be removed from a system to correct the charge inside, always use a
recovery or recycling device.
! WARNING
- To prevent personal injury,
wear safety glasses and gloves when handling
refrigerant
.
1. Check subcooling and superheat.Systems with TXV application should have a subcooling of
9±2°F and superheat of 9 to 11°F.
a.If subcooling and superheat are low,adjust TXV to 9 to 11°F superheat,then check subcooling.
NOTE:To adjust superheat,turn the valve stem clockwise to increase and counter clockwise to
decrease.
b.If subcooling is low and superheat is high,add charge to raise subcooling to 9±2°F then check
superheat.
c.If subcooling and superheat are high,adjust TXV valve to 9 to 11°F superheat,then check
subcooling.
d.If subcooling is high and superheat is low,adjust TXV valve to 9 to 11°F superheat and remove
charge to lower the subcooling to 9±2°F.
NOTE:Do not adjust the charge based on suction pressure unless there is a gross undercharge.
2. Disconnect manifold set,installation is complete.
Subcooling formula=Sat.Liquid Temp.-Liquid line Temp.
Sub-cooling charging for units with TXV
Summary of Contents for HR18D2VAE
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