Rapid 7500 136 Installation, operation & service manual - page 113
SECTION 15: S
EQUENCE
OF
O
PERATION
101 of 143
The 8.5 Remote Panel incl
u
des S
u
mmer/Off/Winter
s
w
itch and
b
lo
w
er,
bu
rner, and flame fail
u
re
indicators in a NEMA 1 enclos
u
re and temperat
u
re
controller.
Blo
w
er Indicator:
Indicates the air t
u
rno
v
er
u
nit is s
u
pplying po
w
er to
the main fan motor
v
ia the motor controls.
B
u
rner Indicator:
Indicates that the air t
u
rno
v
er
u
nit has s
u
pplied
po
w
er
w
hich opens the main f
u
el sh
u
t off
v
al
v
es.
Flame Fail
u
re Indicator:
The
bu
rner control mod
u
le has experienced a fa
u
lt
and
w
ill need to
b
e reset. The
bu
rner control mod
u
le
m
u
st
b
e reset at the air t
u
rno
v
er
u
nit. Refer to the
Maintenance and Tro
ub
le Shooting sections of this
man
u
al to determine the ca
u
se of the fa
u
lt.
S
u
mmer/Off/Winter S
w
itch:
S
u
mmer position:
The
b
lo
w
er
w
ill operate
w
itho
u
t the
bu
rner for
s
u
mmer
v
entilation.
Winter position:
The
b
lo
w
er and
bu
rner
w
ill operate as needed for the
application to maintain airflo
w
and temperat
u
re.
The On-Off / Staged / Mod
u
lating temperat
u
re
controller (
w
hether space / discharge / ret
u
rn air)
w
o
u
ld
b
e set from here.
15.1.3 DDC - Ready Option
The DDC-ready option pro
v
ides inp
u
ts to recei
v
e
control signals from a c
u
stomer determined control
system and o
u
tp
u
ts to pro
v
ide seq
u
ence stat
u
s to the
same. With this option, the c
u
stomer's control system
w
o
u
ld s
u
pply the
b
lo
w
er and call for heat on/off
f
u
nction. For temperat
u
re control, this option allo
w
s
for the c
u
stomer to s
u
pply the follo
w
ing inp
u
t signals;
On/Off, T
w
o-Stage or Mod
u
lation (4-20 mA, 0 or 2-10
v
dc). The c
u
stomer may control the temperat
u
re
either
b
ased on discharge, space or ret
u
rn air
temperat
u
re. A discharge sensor is req
u
ired
w
hene
v
er space or ret
u
rn air control is
u
sed to limit
the discharge temperat
u
re for proper air t
u
rno
v
er
u
nit
performance. For optim
u
m efficiency, Rapid
Engineering LLC s
u
ggests to limit discharge
temperat
u
re to 120° F (48.9° C).
15.2 Basic Se
q
uence of Operation
The follo
w
ing is an o
v
er
v
ie
w
of the seq
u
ence of
operation. Depending on the application and options
s
u
pplied
w
ith the air t
u
rno
v
er
u
nit, this can
v
ary
greatly. Thoro
u
ghly re
v
ie
w
all doc
u
mentation for the
air t
u
rno
v
er
u
nit, incl
u
ding the electrical print, to
familiarize and
u
nderstand the act
u
al seq
u
ence of
operation.
Summer (Blower Only)
With po
w
er s
u
pplied to the air t
u
rno
v
er
u
nit and the
S
u
mmer/Off/Winter s
w
itch on the remote panel in the
SUMMER position, po
w
er is s
u
pplied to the
b
lo
w
er
motor starter coil(s), allo
w
ing the
b
lo
w
er motor(s) to
start. The
bu
rner circ
u
it is NOT energized.
Winter (Blower & Burner)
With po
w
er s
u
pplied to the air t
u
rno
v
er
u
nit and the
S
u
mmer/Off/Winter s
w
itch on the remote panel in the
Winter position, po
w
er is s
u
pplied to the heating
circ
u
it.
The flame relay is po
w
ered
u
p thro
u
gh the air
t
u
rno
v
er
u
nit's airflo
w
s
w
itch
w
arm-
u
p
b
ypass timer
circ
u
it, high temperat
u
re limit s
w
itch, and lo
w
gas
press
u
re s
w
itch and high gas press
u
re s
w
itch (if
pro
v
ided).
When com
bu
stion airflo
w
is pro
v
en
b
y the
bu
rner
airflo
w
s
w
itch, the
bu
rner ignition system is
energized.
After the pilot flame or main flame is pro
v
en
b
y the
flame detector, the main and
b
locking
v
al
v
es are
opened and the ignition system is de-energized.
The temperat
u
re control system is po
w
ered
separately and controls the flo
w
of the f
u
el/air
mixt
u
re to maintain applica
b
le space / discharge /
ret
u
rn air set point temperat
u
re.
NOTE: Refer to the separate man
u
fact
u
rer's literat
u
re
incl
u
ded
w
ith the doc
u
mentation shipped
w
ith the air
t
u
rno
v
er
u
nit for proper set-
u
p and operation of the
temperat
u
re controls s
u
pplied.
After the heat exchanger reaches operating
temperat
u
re, the fan controller closes and po
w
er is
s
u
pplied to the air t
u
rno
v
er
u
nit's fan motor starter
coil(s), allo
w
ing the
b
lo
w
er motor(s) to start. The air
t
u
rno
v
er
u
nit's airflo
w
s
w
itch closes and the
w
arm-
u
p
b
ypass timer completes its time o
u
t cycle, remo
v
ing
the
b
ypass circ
u
it and allo
w
ing the
bu
rner to f
u
nction
only as long as airflo
w
is present thro
u
gho
u
t the air
t
u
rno
v
er
u
nit.
Li
g
ht-Off of On/Off Burners
This firing mode is only a
v
aila
b
le for models ha
v
ing
an inp
u
t of 2,500 MBH (732.7 kW) or less.
The com
bu
stion air dampers are adj
u
sted and locked
in place for the most efficient firing rate. Smooth light-
off on gas is achie
v
ed
b
y the
u
se of a slo
w
opening