York YLUA0248 Series, Установка, эксплуатация и обслуживание

Страница: 37 / 158

JOHNSON CONTROLS
37
SECTION 4 – INSTALLATION
FORM 150.73-NM2
ISSUE DATE: 09/07/2020
4
When using the Load Limit feature, the
PWM feature will not function. SIMUL-
TANEOUS OPERATION OF LOAD LIM-
ITING AND TEMPERATURE RESET
(PWM INPUT) CANNOT BE DONE.
COMPRESSOR HEATERS
Compressor heaters are standard on all models. If pow-
er is OFF more than two hours, the crankcase heaters
must be energized for 18-24 hours prior to restarting a
compressor. This will assure that liquid slugging and
oil dilution does not damage the compressors on start.
REFRIGERANT PIPING
General
When the unit has been located in its final position, the
unit piping may be connected. Normal installation pre-
cautions should be observed in order to receive maxi-
mum operating efficiencies. System piping should
conform to the Johnson Controls DX piping guide
form 050.40-ES2 or ASHRAE refrigeration handbook
guidelines. All piping design and installation is the re-
sponsibility of the user.
JOHNSON CONTROLS ASSUMES NO WAR-
RANTY RESPONSIBILITY FOR SYSTEM OP-
ERATION OR FAILURES DUE TO IMPROPER
PIPING, PIPING DESIGN, CONTROL PROB-
LEMS, OR LACK OF OIL RETURN.
Filter driers and sight glasses are shipped loose for field
installation on each refrigerant circuit. Field refriger-
ant piping can be connected to the condensing unit.
All expansion valves, liquid line solenoid valves, and
refrigerant piping are field supplied and installed. TXV
sizing should be equal in size or slightly smaller than
the capacity of the circuit. If multiple coil sections are
utilized, a TXV for each section, sized accordingly,
must be installed.
REFRIGERANT PIPING REFERENCE
R-410A Copper Line Sizing
When selecting pipe diameter and material for remote
condenser piping R-410A systems such as used with
YCRL chillers, it is recommended that ASTM B280
material, type “L” or “K” is used. According to ASME
Standard B31.5-2006 (table 502.3.1), ASTM B280
copper does not require a derate when brazed. By
comparison, ASTM B88 material does take an anneal-
ing penalty when brazing, which, in some applications,
could reduce the calculated yield strength to a level be-
low the system design.
YCRL LINE SIZING NOTES
The YCRL chiller has a maximum design working
pressure of 560 psig, a mechanical high pressure cutout
to shut the unit off at 585 psig, and (the unit) is rated at
650 psig. The maximum discharge pipe diameter used
on YCRL is 2-1/8”.
ASTM B280, type “L” pipe, 2-1/8” diameter has a
pressure rating of 608 psi per ASME B31.5-2006 sec-
tion 504.1.2, with an additional 20% increase allowed
in section 502.2.3 “Ratings: Allowance for Variations
from Normal Operation” for a maximum allowable
pressure of 730 psi.
Type “K” pipe (thicker wall), per ASME B31.5-2006
section 504.1.2, has a rating of 725 psi before the ad-
ditional 20% allowance is taken.
For more details, refer to “ASHRAE Refrigeration
Handbook, Chapter 2” and YORK DX Piping Guide
“Form 050.40-ES2”
Table 4 on page 39 lists refrigerant line connections
sizes per unit model number.