SECTION 17: S
EQUENCE
OF
O
PERATION
51
Table 12: Factory Preset Schedule on TH
8
110 Thermostat
17.2.3 BMS-Ready Control Option
The BMS-ready option pro
v
ides inp
u
ts to recei
v
e
control signals from a c
u
stomer determined control
system. Each BMS inp
u
t is capable of recei
v
ing a
4-20mA or 0 - 10VDC from the control system. On all
air handlers, the b
u
rner mod
u
lation
w
ill be controlled
by the control system. For AM/VAV style air handlers,
the control system can also control the mod
u
lating
damper.
On DDC/BMS-ready systems, no temperat
u
re control
amplifier is installed. Discharge temperat
u
re
monitoring and mod
u
lation
v
al
v
e adj
u
stment are
completed by the c
u
stomer s
u
pplied control system.
For optim
u
m efficiency, Weather-Rite LLC s
u
ggests
to limit the discharge temperat
u
re to 160 °F.
17.3 Basic Air Handler Se
q
uence of Operation
While the control transformer is energized, the
secondary side s
u
pplies 115 VAC to the control
circ
u
it. When the fan s
w
itch is in the "on" position, the
M1 motor starter is energized and starts the blo
w
er
motor. The M1 motor starter a
u
xiliary contact
s
u
pplies
v
oltage to the b
u
rner s
w
itch and "Fan On"
light. When the b
u
rner s
w
itch is in the "on"/"
w
inter"
position, po
w
er is s
u
pplied to the flame control
mod
u
le and the b
u
rner control circ
u
it. The b
u
rner
control circ
u
it incl
u
des the high temperat
u
re limit
s
w
itch and the lo
w
and high airflo
w
press
u
re
s
w
itches. Once the b
u
rner control circ
u
it is satisfied,
then the flame control mod
u
le
w
ill exec
u
te the b
u
rner
ignition seq
u
ence. Once the pilot flame is ignited and
sensed by the UV scanner, the flame control mod
u
le
w
ill open the safety sh
u
toff
v
al
v
e to ignite the main
flame. When the safety sh
u
toff is opened, 115 VAC is
applied to the "B
u
rner On" light and T3 transformer,
the secondary side s
u
pplies 24 VAC to the
temperat
u
re control amplifier. The temperat
u
re
control amplifier controls the mod
u
lating
v
al
v
e based
on the discharge temperat
u
re monitor (and also the
room temperat
u
re monitor, in the case of a DTC
remote panel).
17.3.1 Flame Control
The flame control is a safety de
v
ice and not
ser
v
iceable.
See Pages 51 through 53
for detailed
seq
u
ence of operation.
17.3.2 Fireye
®
M4RT1 Flame Safe
g
uard
This control is located in the center of the main
control panel.
To reset this flame relay, power to it
must be shut off and turned back on.
FIGURE 27: Fireye M4RT1
This is an exposed circ
u
it board one piece control. It
contains a f
u
se to protect itself from external shorts
or o
v
erloads and on its exterior it has fi
v
e lights
w
hich
indicate the operating stat
u
s of the control.
The f
u
nctions of the indicator lights,
w
hich are
located on the programmer mod
u
le, are as follo
w
s.
They are listed in the order yo
u
w
ill find them on the
flame safeg
u
ard and is also the order in
w
hich they
w
ill occ
u
r in the seq
u
ence. The indicators are
act
u
ally a red colored light emitting diode or LED, this
is ho
w
they
w
ill be referred to from no
w
on.
1.
Operatin
g
Control
- This indicator is on
w
hen
po
w
er is present at terminals #1 and #7 of the
flame safeg
u
ard.
Monday - Friday
Saturday - Sunday
Time
Temperature
Fan Settin
g
Time
Temperature
Fan Settin
g
Wake
6:00 AM
68° F
Fan On
6:00 AM
62° F
Fan A
u
to
The air handler
w
ill r
u
n contin
u
o
u
sly.
Temperat
u
re controlled by Maxitrol stat.
The air handler
w
ill r
u
n
w
hen the thermostat calls for heat.
Leave
Un
u
sed
Un
u
sed
Return
Un
u
sed
Un
u
sed
Sleep
5:00 PM
62° F
Fan A
u
to
5:00 PM
62° F
Fan A
u
to
The air handler
w
ill r
u
n
w
hen the thermostat calls for heat.
The air handler
w
ill r
u
n
w
hen the thermostat calls for heat.
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