Year-Round Heat Recovery Preheat System Control - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

YEAR-ROUND HEAT RECOVERY PREHEAT SYSTEM CONTROL

Functional Description
12
PUMP START SETPOINTS:
COOLING SETPOINT = ANYTIME OA
TEMPERATURE IS
ABOVE RA TEMPERATURE.
HEATING SETPOINT = ANYTIME OA
TEMPERATURE IS
BELOW SA TEMPERATURE SETPOINT
DETERMINED BY SUPPLY
SYSTEM CONTROL.
Item
No. Function
1,2 Fans start and enable pump control upon
HVAC demand for ventilation (See FAN
SYSTEM START-STOP CONTROL).
3,4 Dampers close upon fan shutdown.
5 Pump runs when temperature conditions are
suitable for beneficial results.
6,10 The OA and RA temperature difference
determines when pump operation is beneficial.
7 Mixing valve prevents too much RA heat from
being transferred such that the SA temperature
ENGINEERING MANUAL OF AUTOMATIC CONTROL
3.0
DEGREES
1.5
DEGREES
AIR HANDLING SYSTEM CONTROL APPLICATIONS
26
11
OPEN
4
EXHAUST
N.C.
EA
COIL
ON
5
100
28
7
30
6
C
OA
N.C.
OPEN
3
exceeds that demanded by the HVAC control
system. Mixing valve also keeps water
entering the exhaust coil from dropping below
freezing to prevent the coil from frosting.
8,9 HVAC system SA temperature setpoint
determines valve position in winter.
11 Operator information.
12 Dynamic graphic sequence display permits
the operator to adjust program setpoints.
233
2
ON
PUMP
PERCENT OPEN
TO SUPPLY COIL
SETPOINT
8
N.C.
9
N.O.
SUPPLY FAN
SUPPLY
COIL
ON
1
HEATING SETPOINT DETERMINED
BY SUPPLY SYSTEM CONTROLS.
10
24
RA
13
28
SA
M15167