FORM 100.10-NOM2
21
YORK INTERNATIONAL
When using ethylene glycol or other
antifreeze solutions, consult the
YORK Sales Engineer for the required
derating of each coil. It will be neces-
sary to give the percentage of ethyl-
ene glycol required.
STEAM COILS
The operation of steam coils is dependant on air flow
quantity and temperature. Consult the submittal issued
for each specific unit for above information.
Steam coils available are non-freeze coils and standard
steam.
There is no coil that is absolutely free
from freezing. For winterizing - See
“Freeze Protection” section. Also re-
fer to industry guidelines such as
the ASHRAE Handbook and ARI
Guidelines.
HEATING COILS
Hot Water Coils
The temperature rise of the air leaving the coil is de-
pendent on the airflow across the coil, the gallons of
water flow through the coil and the entering water tem-
perature into the coil. Consult the submittal for each
specific job for the above information.
DIRECT EXPANSION COILS (SPLIT SYSTEM)
Each coil must be installed with the suction header on
the entering air face of the coil and with the suction
connection at the lower end. The orientation of the re-
frigerant distributor is not critical but the distributor tubes
must not be kinked or bent in a non-uniform configura-
tion. (See Figure 21)
An individual expansion device must be provided for
each distributor.
Thermostatic expansion valves are to be equipped with
external equalizer tubes that are field connected to the
suction line. The valve should be sized in accordance
with the manufacturers recommendations, allowing ap-
proximately 35 psi pressure drop through the coil and
distributor at full load. Do not oversize the valve. Fol-
low the valve manufacturer’s instructions on the loca-
tion of the thermostatic bulb. Proper expansion valve
operation is necessary in order to realize the rated coil
capacity.
When a DX type coil is operated with a suction tem-
perature below 32°F, a build up of frost will occur on
the finned surface. It is, therefore, not recommended to
operate DX coils for air conditioning purposes at below
freezing suction temperatures. If the full load operating
point for the coil is selected at a “safe” temperature, a
system analysis is required to check for the lowest prob-
able suction temperature at light load conditions. Suc-
tion pressure controlled hot gas bypass valves are avail-
able from various control manufacturers to maintain an
adequate minimum suction temperature.
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