C NC NO 1 S C 1 S C M 1 2 3 4 5 RESTRICTOR RC1 RC2 V PE1 TE1 LL1 OFF ON EP1 M DA SEQUENCE OF OPERATION When the fan starts solenoid air valve (EP1) energizes and passes control air to drive damper motor (DM1) fully. EP1 also passes control air to humidity controller (H1). Receiver controller (RC1) senses the discharge air temperature via transmitter (TT2). RC1 sends its signal to modulate face & bypass damper motor (DM2). RC1 also sends its signal to feed receiver controller (RC2). RC2 senses the outside air temperature via transmitter (TT1). RC2 passes its signal to modulate control valve (V1). H1 sends its signal to modulate humidifier valve (V2). If low limit (LL1) senses a temperature below its set point on anyone foot of its element the fan will shut down. If pressure switch (PE1) senses a loss of steam pressure in cold weather as determined by controller (TE1) the fan will shut down. The humidifier must be valved off for summer operation. HL1 This is a system installed in a hospital, serving patient rooms; therefore, the fan runs continuously. If the fan were to shut down at times, you may consider controlling the valves from a pneumatic low limit with automatic reset between the outside air damper and the preheat coil, preventing over-heating of the duct when the fan is down. 7.49 100% OUTSIDE AIR FAN CONTROL EXAMPLE TE1 40˚F 4 NC NO NC FACE & BYPASS DAMPER STEAM HUMIDIFIER SUPPLY FAN HL1 1 3 1 2 5 M PE1 NO DM1 3# -13# DM2 3# - 13# LL1 40˚F V2 NC STEAM STEAM TRAP CONDENSATE V1 NO 14# - 17# RESTRICTOR STEAM PROVING SWITCH H1 SET 85% RH TT2 TT1 STEAM EP1 DA SET 55˚F SET 38˚F = 5% OPEN 32˚F = 100% OPEN NOTE: RC2'S 100% OPEN MAY HAVE TO BE ALTERED TO SUIT SYSTEM. SUPPLY AIR TEMP. OSA TEMP.
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