S-1. SEQUENCE OF OPERATION
GENERAL:
The AHU is a mixed air variable volume system with a supply fan S-1. an exhaust/return fan ER—1, a chilled water coil, and a hot water preheat coil.
S—1. is equipped with a variable frequency drive (VFD) for speed control of the fan.
START/STOP CONTROL:
(this has been modified to use motor frequency as proof of operation instead of current sensing relay)
The Base _____ __ (BAS) starts ER—1 through an optimal start program for morning
warm—up based on building occupation time, earliest and latest start
times, outside air and space temperatures. When ER—1 is proven to be
running via current sensing relay CSR—2, S—1. starts and ramps up to
minimum speed. S—1 proof is accomplished via current sensing relay
CSR—1. When building occupation time is reached, the outside and
exhaust air dampers open, and the return air damper closes to their
respective minimum positions. When the system goes into unoccupied
mode, fans S—1 and ER—1 are stopped and the dampers go to their normal
positions.
STATIC PRESSURE CONTROL:
Supply static pressure sensed by PTE—1 is reset from PTE—2 located
2/3 downstream of the supply. The S—1 VFD is modulated, controlling
fan speed to maintain the supply static pressure setpoint of 2” W.C.
(adjustable). A signal returns from the VFD to indicate fan speed for
monitoring purposes. PTE—3 sensing supply air flow is used for
monitoring purposes only. Hi fan static or suction sensed by DPS—1 or
DPS—2 will shut down S—1 on such a condition. The fan is not allowed
to start until the switch is reset.
DISCHARGE CONTROL:
The cooling valve V—1, the heating valve V—2, and the O.A./R.A./E.A. dampers are modulated in sequence to maintain the discharge air temperature setpoint of 55 degrees F (adjustable) sensed by TTE—1. The discharge humidifier is controlled from space humidity sensor at 30%. RH (adjustable). Humidity hi limit H—1 shall override and control duct humidity at 85%. RH (adjustable).
MIXED AIR CONTROL:
When the mixed air temperature sensed by TTE-2 falls below the
setpoint of 55 degrees F (adjustable), the O.A./R.A./E.A. dampers are
modulated closed to minimum position reducing the outside air intake
and increasing the return air. Mixed air control shall be locked out
and the O.A./R.A./E.A. dampers go to minimum position when the outside
air temperature sensed by TTE—3 rises above 60 degrees F (adjustable). If a
low temperature of 35 degrees F is sensed by LTDE—1 at the coils, S-1
will shut down and the O.A./R.A./E.A. dampers will close. The fan
shall not be allowed to start again until the switch is reset.
NIGHT OVERRIDE:
During unoccupied mode, the system can be manually overridden into
occupied mode for an extended period of one hour (adjustable) hen ,the remote
switch Sw—1 is depressed. SW—1 has no effect during occupied mode.
S-2 SEQUENCE OF OPERATION
GENERAL:
The AHU is a mixed air variable volume system with a supply fan S—
1. an exhaust/return fan ER—1. a chilled water coil, and a hot water
preheat coil. S—2 is equipped with a variable frequency drive (VFD)
for speed control of the fan.
START/STOP CONTROL:
The BAS starts ER—2 through an optimal start program for morning
warm—up based on building occupation time, earliest and latest start
times, outside air and space temperatures. When ER—2 is proven to be
running via current sensing relay CSR—2, S—2 starts and ramps up to
minimum speed. S—2 proof is accomplished via current sensing relay
CSR—2. When building occupation time is reached, the outside and
exhaust air dampers open, and the return air damper closes to their
respective minimum positions. When the system goes into Unoccupied
mode, fans S—2 and ER—21 are stopped and the dampers go to their normal
positions.
STATIC PRESSURE CONTROL:
Supply static pressure is sensed by PTE—1 is reset from PTE2 located
2/3 downstream.)of the supply. The S—2 VFD is modulated, controlling
fan speed to maintain the supply static pressure setpoint of 2’W.C.
(adjustable). A s-i-al returns from the VFD to indicate fan speed for
monitor VS purposes. PTE-3 sensing supply air flow is used for
monitoring purposes only. Hi fan static or suction sensed by DPS—1 or
DPS-2 will shut down S—1 on such a condition. The fan is not allowed
to start until the switch is reset.
DISCHARGE CONTROL:
The cooling valve V—1, the heating valve V—2, and the
O.A./R.A./E.A. dampers are modulated in sequence to maintain the•
discharge air temperature setpoint of 55 degrees F (adjustable) sensed by
TTE—1. The discharge humidifier is controlled from space humidity
sensor at 307. RH (adjustable). Humidity hi limit H—1 shall override and
control duct humidity at 857. RH (adjustable).
MIXED AIR CONTROL:
When the mixed air temperature sensed by TTE—2 falls below the
setpoint of 55 degrees F (adjustable), the O.A./R.A./E.A. dampers are
modulated closed to minimum position reducing the outside air intake
and increasing the return air. Mixed air control shall be locked out
and the O.A./R.A./E.A. dampers go to minimum position when the outside
air temperature sensed by TTE—3 rises above 80 degrees F (adjustable). If a
low temperature of 35 degrees F is sensed by LTDE—1 at the coils, S—2
will shut down and the O.A./R.A./E.A. dampers will close. The fan
shall not be allowed to start again until the switch is reset..
NIGHT OVERRIDE:
During unoccupied mode, the system can be manually over-ridden into
occupied mode for an extended period of one hour (adjustable) when the remote
switCh SW—1 is depressed. SW—1 has no effect during occupied mode.
S-3 SEQUENCE OF OPERATION
GENERAL:
The AHU .j.s a mixed air variable volume system with a supply fan S-.
3. an exhaust/return Ian ER—3, a chilled water coil, and a hot water
preheat coil. S—3 and ER-3 are equipped with a variable frequency
drives (VFD) ‘for speed control of the fans.
START/STOP CONTROL:
The BAS starts ER—3 and ramps up to minimum speed through an
optimal start program ‘for morning warm—up based on building occupation
time, earliest and latest start times, outside air and space
temperatures. When ER—3 is proven to be running via current sensing
relay CSR-2, S—3 starts and ramps up to minimum speed. 5—3 proof is
accomplished via current sensing relay CSR—1. When building
occupation time is reached, the outside and exhaust air dampers open,
and the return air damper closes to their respective minimum
positions. When the system goes into unoccupied mode, fans S—3
and ER—3 are stopped and the dampers go to their normal positions.
STATIC PRESSURE CONTROL:
Supply static pressure sensed by PTE—1. is reset from PTE—2 located
2/3 downstream of the supply. The S—3 and ER-3 VFDS are modulated
together, controlling ‘fan speed to maintain the supply static pressure
setpoint of 2”W.C. (adjustable). A signal returns from the VFDs to indicate
fan speed ‘for monitoring purposes. PTE—3 and PTE—4 sensing supply and
return air flow are used for monitoring purposes only. Hi fan static
or suction sensed by OPS—)., DPS—2, or DPS—3 will shut down the
respective fan on such a condition. The fan is not allowed/to start
until the switch is reset.
DISCHARGE CONTROL:
The cooling valve V—1 and the O.A./R.A./E.A. dampers are modulated
in sequence to maintain the discharge air temperature setpoint of 55
degrees F (adjustable) sensed by TTE—1. The discharge humidifier is
controlled from space humidity sensor at 30Y. RH (adjustable). Humidity hi
limit H—1 shall override and control duct humidity at 95Y. RH(adjustable).
MIXED AIR CONTROL:
When the mixed air temperature sensed by TTE—2 falls below the
setpoint of 55 degrees F’ (adjustable), the D.A./R.A./E.A. dampers are
modulated closed to minimum position reducing the outside air intake
and increasing the return air. Mixed air control shall be locked out
and the O.A./R.A./E.A. dampers go to minimum position when the outside
air temperature sensed by TTE—3 rises above 60 degrees F (adjustable). If a
low temperature of 35 degrees F is sensed by LTDE—l. at the coils, 5—3
will shut down and the O.A./R.A./E.A. dampers will close. The fan
shall not be allowed to start again until the switch is reset.
NIGHT OVERRIDE:
During unoccupied modes the system can be manually over ridden into
occupied mode for an extended period of one hour (adjustable) when the remote
switch SW—1 is depressed. SW—1 has no effect during occupied mode.
VAV BOX CONTROL
GENERAL:
The system consists of a VAV or CAy box with hot water reheat coil.
SPACE CONTROL:
Pneumatic thermostat T—1 modulates the VAV box damper and reheat
coil valve in sequence to maintain a space temperature setpoint c-f 72
degrees F (adjustable). Below setpoint, air flow will be at minimum and the
reheat valve V—1 is modulated open. Above setpoint, the valve is closed and the box damper is modulated open to provide cooling.
HOT WATER SUPPLY SYSTEM CONTROL
GENERAL:
The system consists of 2 boilers and associated pumps.
HOT WATER SUPPLY CONTROL:
Control of the H WS is internal thru boiler controls.
HOT WATER BYPASS CONTROL:
When the differential pressure sensed by DPR— 1 across the HW
pumps becomes excessive, valve V—1. is modulated to reduce pressure.
TERMINAL REHEAT HOT WATER BYPASS CONTROL:
When the differential pressure
sensed by DPR—2 across the TRW pump becomes excessive, valve V—2 is modulated to reduce pressure.
TRW LOCKOUT:
When the outside air temperature rises above 60 degrees F (adjustable),the BAS closes valve V—3 restricting the flow of HWS to the VA’) boxes.
BOILER COMBUSTION DAMPER CONTROL:
When either boiler is on, the interlocked combustion damper will -open. Status of the boilers is monitored thru the BAS.
HOT WATER PUMP CONTROL:
Pumps are started and stopped t
hru the BAS base
d on occupancy.—Status of the pumps is
via current sen
sing relay.
LAB 2 CONTROL
GENERAL:
The system consists of a lab containing 2 fume hoods and a VAV box
supplying the lab.
FUME HOOD START/STOP AND CONTROL:
A fume hood is started and stopped thru the operator panel. When
the BAS receives a signal that any fume hood has been started, fume
hood exhaust fan E—1. is started. If none of the hoods are in
operation, E—1 is off. The fume horod controller FHC—1 maintains a
constant air velocity of 100 fpm (adjustable) thru the fume hood sash based
on the sash position and the air flow thru the fume hood exhaust duct,
by modulating the fume hood exhaust damper.
PERCHLORIC FUME HOOD START/STOP CONTROL:
The perchioric fume hood exhaust fan E—3 is started directly thru
the fume hood switch provided by others. Current sensing relay CSR—1
is for monitor only.
VAV BOX CONTROL:
Room sensor TTE-i, thru the BAS, modulates the VAV box damper and
reheat coil valve in sequence to maintain a space temperature setpoint
of 72 degrees F (adjustable). Below setpoint, afr flow is at minimum and the
reheat valve V—1 is modulated open. Above setpoint, the valve is
c
osed and the box damper is modulated open to provide cooling.
LAB CONTROL:
The BAS monitors the supply air flow to the lab at the VAV box, the
room exhaust air flow, and the fume hood exhaust air flow thru
respective velocity sensors. Control of space temperature is thru the
VAV box controls as supply air volume to the room is varied.
Depending on how much air is supplied thru the VAV box and how much
air is exhausted thru the fume hoods, the BAS modulates the room
exhaust damper to maintain a CFM differential setpoint of 200 CFM
(adi ) total exhaust (room exhaust + fume hood exhaust + perchioric
fume hood exhaust) air flow greater than room supply air flow, keeping
the lab at a negative pressure.
If the CFII setpoint cannot be maintained as the differential rises
above setpoint (supply too low or exhaust too high), the VAV box
damper will be overridden to modulate open providing more supply CFM
to the room, while the reheat valve will be modulated open attempting
to maintain space temperature setpoint.
If the CFM setpoint cannot be maintained as the differential drops
below setpoint (supply too high or exhaust too low with the
possibility of the lab becoming positive), the VAV box damper will be
overridden to modulate closed providing less supply CFM to the room.
LAB 3 CONTROL
GENERAL:
The system consists of a lab containing 2 fume hoods and
a VAV box
supølying the lab.
FUME HOOD START/STOP AND CONTROL:
A fume hood is started and stopped thru the operator
panel. When the BAS receives a signal that any fume hood has been start
ed, fume hood exhaust fan E—1 is started. If none of the hoods are
in
operation, E—1 is off. The fume hood controller FHC—1. or F
HC—2
maintains a constant air velocity of 100 1pm (adjustable) thru the fume
hood
sash based on the sash position and the air flow thru the fume hOod
exhaust duct or by sensing wall air velocity, by modulating th
e fume
hood exhaust damper.
VAV BOX CONTROL:
Room sensor TTE—1., thru the BAS, modulates the VAV box damper a
nd
reheat coil valve in sequence to maintain a space temper
ature setpoint
of 72 degrees F (adjustable). Below setpoint, air flow is at minimum and
the
reheat valve V—1 as modulated open. Above setpoint, the valve is
closed and the box damper is modulated open to provide cooling.
LAB CONTROL:
The BAS monitors the supply air flow to the lab at t
he VAV box, the
-am exhaust air flow, and the fume hood exhaust air flow
thru
spective velocity sensors. Control of space temper
ature is thru the
VAV box controls as supply air volume to the room is varie
d.
Depending on how much air is supplied thru the VAV box and h
ow much
air is exhausted thru the fume hoods, the BAS modulates th
e room
exhaust damper to maintain a CFM differential setpoint of 2
00 CFM
(adjustable) total exhaust (room exhaust + fume hood exhaust) air flow
greater than room supply air flow, keeping the lab at a neg
ative
pressure.
If the CFM setpaint cannot be maintained as the differenti
al rises
above setpoint (supply too low or exhaust too high), th
e VAV box
damper will be overridden to modulate open providing more
supply CFM
to the room, while the reheat valve will be modulated open
attempting
to maintain space temperature setpoint.
If the CFM setpoint cannot be maintained as the differential dr
ops
below setpoint (supply too high or exhaust too low with the
possibility of the lab becoming positive), the VAV box damper
will be
overridden to modulate closed providing less supply CFM to
the room.
LB CONTROL
GENERAL:
The system consists of a lab containing 2 fume hoods and a YV box supplying the lab.
FUME HOOD ST,RT/STOP ND CONTROL:
P fume hood is started and stopped thru the operator panel. When the BS receives a signal that any fume hood has been started, fume hood exhaust fan E—1 is started. If none of the hoods are in operation, E—1 is off. The fume hood controller FHC— 1. or FHC—2 maintains a constant air velocity of 100 fpm (adjustable) thru the
fume hood sash based on the sash position and the air flow thru the fume
hood exhaust duct, by modulating the fume hood exhaust damper.
VAV BOX CONTROL:
Room sensor TTE—1, thru the BAS, modulates the VAV box damper and reheat coil valve in sequence to maintain a space temperature set poin tof 72 degrees F (adjustable). Below set point, air flow is at minimum and the reheat valve V—1 is modulated open. Above setpoint, the valve is closed and the box damper is modulated open to provide cooling.
LAB CONTROL:
The BS monitors the supply air flow to the
lab at the VAV box, the room exhaust air flow, and the
fume hood exhaust air flow thru respective velocity sensors. Control of space temperature is thru the(V box controls as supply air volume to the room is varied. Open ding on how much air is supplied thru the VAV box and how much air is exhausted thru the fume hoods, the BAS modulates the room exhaust damper to maintain a CFM differential. setpoint of 200 CFM(adjustable) total exhaust (room exhaust + fume hood exhaust) air flow greater than room supply air flow, keeping the lab at a negative pressure.
If the CFM setpoint can not be maintained as the differential rises above setpoint (supply too low or exhaust too high), the VAV box damper will be over ridden to modulate open providing more supply CFM to the room, while the reheat valve will be modulated open attempting to maintain space temperature setpoint.
If the CFM setpoint can not be maintained as the differential drops below setpoint (supply too high or exhaust too low with the possibility of the lab becoming positive), the VAV box damper will be overridden to modulate closed providing less supply CFM to the room.
LAB 7 CONTROL
GENERAL:
The system consists of a lab containing 2 fume hoods and a VAV box supplying the lab.
FUME: HOOD START/STOP AND CONTROL:
A fume hood is started and stopped thru the operator
panel. When the BAS receives a signal that any fume hood has been started, fume hood exhaust fan E—1 is started. If none of the hoods are
in operation, E—1 is off. The fume hood controller PHC—1 or FHC—2
maintains a constant air velocity of 100 fpm (adjustable) thru the fume
hood
sash based on sensing wall air velocity, by modulating the fume hood
exhaust damper.
VAV BOX CONTROL:
Room sensor TTE—1, thru the BAS, modulates the VAV box damper and
reheat coil valve in sequence to maintain a space temperature set point
of 72 degrees F (adjustable). Below setpoint, air flow is at minimum and the
reheat valve V—1 is modulated open. Above setpoint, the valve is
closed and the box damper is modulated open to provide cooling.
LAB CONTROL:
The BAS monitors the supply air flow to the lab at the VAV box, the
room exhaust air flow, and the fume hood exhaust air flow thru
respective velocity sensors. Control of space temperature is thru the
IAV box controls as supply air volume to the room is varied.
Depending on how much air is supplied thru the VAV box and how much
air is exhausted thru the fume hoods, the BAS modulates the room
exhaust damper to maintain a CFM differential setpoint of 200 CFM
(adjustable) total exhaust (room exhaust + fume hood exhaust) air flow
greater than room supply air flow, keeping the lab at a negative
pressure.
If the CFM setpoint cannot be maintained as the differential rises
above setpoint (supply too low or exhaust too high), the VAV box
damper will be overridden to modulate open providing more supply CFM
to the room, while the reheat valve will be modulated open attempting
to maintain space temperature setpoint.
If the CFM setpoint cannot be maintained as the differential drops
below setpoint (supply too high or exhaust too low with the
possibility of the lab becoming positive), the VAV box damper will be
overridden to modulate closed providing less supply CFM to the room.
LAB B CONTROL
GENERAL:
The system consists of a lab containing 1 fume hood and a VAV box
supplying the lab.
FUME HOOD START/STOP AND CONTROL:
A fume hood is started and stopped thru the operator panel. When
the BAS receives a signal that any fume hood has been started, fume
hood exhaust fan E—1 is started. If none of the hoods are in
operation, E—1 is off. The fume hood controller FHC—1 maintains a
constant air velocity of 100 fpm (adjustable) thru the fume hood sash based
on the sash position and the air flow thru the fume hood exhaust duct,
by modulating the fume hood exhaust damper.
VAV BOX CONTROL:
Room sensor TTE—1, thru the BAS, modulates the VAV box damper and:
reheat coil valve in sequence to maintain a space temperature setpoint
of 72 deg rees F iTV f 1 ow1 a € in i man
reheat va’Tis modulated open. Above setpoint, the valve is
closed and the box damper is modulated open to provide cooling.
—. —.---.-. —.. -—. ——
LAB CONTROL: j/
The GAS monitors the supply air flow to the lab t t e VAV box, the
om exhaust air flow, the exhaust air flow thru
respective velocity sensors. Control of space temperature is thru the
VAV box controls as supply air volume to the room is varied.
Depending on how much air is supplied thru the VAV box and how much
air is exhausted thru the fume hood, the GAS modulates the room
exhaust damper to maintain a CFM differential setpoint of 200 CFM
(adjustable) total exhaust (room exhaust + fume hood exhaust) air flow
greater than room supply air flow, keeping the lab at a negative
pressure.
If the CFM setpoint cannot be maintained as the differential rises
above setpoint (.supply _... too low or exhaust too high) the VAV box
— —• —‘.-— - —. -.-,----—.--— —.. .--‘ - —..‘ .
(damper will be overridden to modulated open providing more supply CFM
to the room, w i e the reheat valve wi be modulated open attempting
to maintain space temperature setpoint.
If the CFM setpoint cannot be maintained as the differential drops
below setpoint (supply too high or exhaust too low with the
possibility of the lab becoming positive), the VAV box damper will be
overridden to modulate closed providing less supply CFM to the room.
EXHAUST FAN E-1 CONTROL:
Fume hood exhaust fan E—1 is frequency modulated to control a constant static pressure at the fan inlet based on fume hood operation. (CHECK WHERE THE SP SENSOR IS LOCATED)
The VFD is modulated to maintain
a total suction static
pressure et,oint of 1”W.C. (adjustable) i
n the fume hood exhaust.
Suction static
is sensed by PTE—1 6c PTE—2 and is controlled by selecting the
lower one requiring the greater suction.
EXHAUST FAN E-2 CONTROL:
Storage room exhaust fan E—2 is started and stopped based on
occupancy. Current sensing relay
CSR—2 indicates fan status.
Return air temperature sensor TTE—1 is for monitor only..