York D1SV300 Installation Instructions Manual page 17

After the pre-start check list has been completed:
1.
L
-) .
Start the supply air blowers,
Adjust the resistances in both the supply and the return
duct systems to balance the air distribution throughout
the conditioned space. The job specifications may re-
quire that this balancing be done by someone other than
the equipment installer.
To check the supply alr CFMafter the initial balancing has
been completed:
1. Drl[l two 5/16" holes (A & B) as shown in Figure 16.
2. Install two 1/4" O.D. tubes, one between the filters and
the air entering side of the evaporator coil and one be-
tween the supply air blower(s) and the air leavingside
of the evaporator coil.
RIGHT END
VIEW
' DIA.
5{16" DIA.
J
B
o \
= UNIT
DRAIN
—
— —
— 30''--- +–– -33" —
FIG. 16 – HOLE LOCATIONS
FOR SUPPLY AIR
CFM CHECK
NOTh": To get a proper staric pressurereading, [he sensing
tubes should (A) be inserted through the rear or
condensate drain side of the unit (B) be located
approximately 6 inches away from the coil surface
and as close to the center of the coil height as pos-
sible (C) extend into the unit approxiwutely 12
inches.
3, Make sure thfit the access panels [or
both
the suppl} mr
blower motor findt be filters ~le secured. These panels do
not hove to be secuJeclwherr the 1/4 ]nch tubes entel
the units because the blowel and falter compartments
operate at a negative pressure.
4, Make sure that the tube openings are perpend]cu]ar to the
Iir tltnv so that vekrcity pressure will not affect the statIc
L
pressure reurilngs.
CAUTION.
530.25-N2
If this method is used, the holes must be sealed
with dot plugs (P/N 029-13880) or equivalent
to prevent moisture from leaking into the unit.
I
1
)
,
1
;0
80
43
160 1;0 1;0
1;0
PERCENT NOMINAL CFM
[
% OF NOMINAL CFM
MODE L
80
90
100
I
110 120
C.F .M.
DSV300 8000
I
9000
10000 11000 12000
DSV360
9600 10800 12000
13200 14400
DSV480
12800
I 14400 16000 17600 19200
FIG. 17 –
PRESSUREDROP ACROSSA DRY
EVAPORATOR COl L VS SUPPLY AIR CFM
5. Usingan inclined manometer, determine the pressure drop
across a dry evaporator coil. Since the moisture on an evap-
orator coil may vary greatly, measuring the pressure drop
across a wet coil under field conditions would be inaccu-
rate,
NOTE: Disconnect the compressors befhre taking an,v test
measurements to
assure a
drv
evaporator coil.
6. Knowing the pressure drop across a
dry coil,
the
actual
CFM through the unit can be determined from the curve
in Figure 17.
,~rOTk-. On D SVun[ts a[iau- LwhitHe dampers ih unit and
termitlal bc)xesill du(t s)'stem nwst be c>pen when
checkitlg air quattti[>',
If the CFM ISabove or below the specified value, the supply
air motor pulley may have to be readjusted, Alter one hour
of operation, check all belts and pulleys for t]ghtness and
alignment.
WAR,VI,}'G.Failure to properly adjtist the total system CFM
can result in extensive blower damage.
Cerltral Environmental Systems 17