Engineered air EngA CU Series, Инструкция по установке, эксплуатации и обслуживанию

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CU MANUAL
IOM-14 8 of 46 Feb 06 R4
2. Condensing Unit At The Same Elevation As The Evaporator.
Select suction and liquid lines from the appropriate tables. Horizontal suction lines should slope down in
the direction of flow with a 1:200 slope.
3. Condensing Unit Located Below The Evaporator.
This arrangement should only be considered when other options are not available.
With the compressor below the evaporator, oil return in the suction line is helped by gravity. Horizontal
runs are sloped down in the direction of flow with a 1:200 slope.
The liquid must travel upwards, and there are several issues that must be addressed. As the liquid travels
upward, it must fight gravity and it will LOSE pressure at the rate of 0.5 psig per vertical foot. Adequate
subcooling is required to counteract the pressure losses due to vertical rise, plus the pressure drop due to
friction losses and accessories. Standard subcooling for most condensing units is 10°F, (5°C).
In the off cycle, all liquid refrigerant in the line will drain down to the condenser by gravity. When the
system restarts, time is required for the liquid refrigerant to fill the liquid line and travel to the TX valve. A
low-pressure control bypass timer may be required, to allow time for liquid to reach the TX valve, and
prevent the system from short-cycling during startup.
An EngA Intercooler (optional) may be installed at the TX valve to improve performance and reduce flash
gas during fluctuating load conditions.
Consider installing an additional liquid line sight glass at the TX valve to ensure that a solid column of liquid
reaches the TX valve. This simple step at installation time can save many hours of troubleshooting if there
is a flash gas issue.
PIPING RECOMMENDATIONS
Underground Piping
Caution:
Underground Piping is not recommended.
Improper installation of a condensing unit with underground piping will result in
equipment failure.
Consult Factory on all systems with underground refrigerant piping.
Underground piping will void compressor warranty unless specifically authorized by the
factory.
In the off cycle, the refrigerant charge will migrate to the coldest location. Typically, ground temperatures
are cooler than air temperatures, and the underground piping becomes the coolest location. In this case
the refrigerant charge will migrate to underground piping.
When the compressor starts, any liquid refrigerant in the suction line will enter the compressor causing
both diluted oil and slugging. Either condition will reduce the life of the compressor.