88 YORK INTERNATIONAL
To maintain the remote setpoint described on page 79,
the EMS Pulse Width Modulation input (terminals 75 and
76) on the Digital Input Board must be refreshed every
30 minutes or less (20 minutes is recommended). In
other words, to maintain the 40°F (4.4°C) RWT setpoint,
the contacts between terminals 75 and 76 must be closed
for a period of 8.5 seconds every 20 minutes. If this is
not refreshed at least every 30 minutes, the Micro Logic
Board will take this as a signal to change the RWT
setpoint back to the original setpoint of 25°F (–3.9°C)
on the Control Panel. See Fig. 62, 63, and 64 for loca-
tion and wiring to TB8.
DUAL CIRCUIT UNITS
FIG. 62 – COMPONENT LOCATION
“OPTIONAL” REMOTE UNLOADING AND DEMAND
LIMITING
A forced unload of the system, independent of water
temperature demand, can be accomplished by closing
a “dry” contact connected between terminals 73 & 74 of
TB8 which is wired into terminals 9 & 10 of the optional
Digital Input Board. This control feature forces turn-off
of the lag compressor. Note: Switch 4 must be in the
“ON” position on the Micro Logic Board. (See Fig. 50.)
See Fig. 62, 63, and 64 for location and wiring to TB8.
LD01635
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