FloAire Compact Direct Fired Heater - Manual (Page 17)

17
Flame Safety Controller
Pulley Combination Chart
Motor RPM 1725
1/3 to 1-1/2 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2
AX BELTS 1VP50 3.4 4.4 3.6 4.6
Open Closed
BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0
AK32H 3 3.2 1941 1995 2048 2102 2156 2210 2264 2318 2372 2426 2480
1/3 to 1-1/2 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2
AX BELTS 1VL44 2.8 3.8 3 4
Open Closed
BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0
AK32H 3 3.2 1617 1671 1725 1779 1833 1887 1941 1995 2048 2102 2156
1/3 to 2 HP MOTOR PULLEY Dd1 Dd2 Pd1 Pd2
AX BELTS 1VL40 2.4 3.4 2.6 3.6
Open Closed
BLOWER PULLEY DATUM DIAMETER PITCH DIAMETER 5 4 1/2 4 3 1/2 3 2 1/2 2 1 1/2 1 1/2 0
AK66 6.2 6.4 701 728 755 782 809 836 863 889 916 943 970
AK54 5 5.2 863 896 929 962 995 1028 1062 1095 1128 1161 1194
AK46 4.2 4.4 1019 1059 1098 1137 1176 1215 1255 1294 1333 1372 1411
AK39 3.5 3.7 1212 1259 1305 1352 1399 1445 1492 1539 1585 1632 1678
AK32 3 3.2 1402 1455 1509 1563 1617 1671 1725 1779 1833 1887 1941
TURNS ON MOTOR PULLEY
7
I
N
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BL
OW
E
R
Pulley Combination Chart
TURNS ON MOTOR PULLEY
TURNS ON MOTOR PULLEY
Sequence of Operation
The direct-fired heater is most easily understood when broken down into smaller individual systems.
There are two main systems, a make-up air fan and a heater. The make-up air fan consists of a blower
and motor. The heater may be further broken down into two control systems, the Flame Safety Control
(FSC) and the Modulating Gas System (MGS). The burner mixes air with the gas (Natural or LP) which
heats the air.
Flame Safety Control
The first system to understand is the Flame Safety Control. The FSC
is there only to monitor the flame, NOT to control temperature. The
FSC uses a flame rectification sensor mounted on the pilot assembly
to detect the presence of flame in the burner. The FSC is also wired
into an airflow switch, which tells it whether there is proper airflow
through the unit (not just any airflow, but proper airflow). Proper airflow
occurs when there is a .15 in. w.c. to .80 in. w.c. differential
pressure drop across the burner. The FSC controls the opening of
the redundant solenoid gas valves and the operation of the spark
igniter to initiate a pilot flame upon start-up.
Upon a call for heat, there is a 15 second Pilot Trial For Ignition (PTFI).
During PTFI, the FSC opens the pilot gas valve and allows gas to flow
to the pilot assembly. At the same moment, the spark igniter is started,
causing the spark to ignite the pilot gas. When the flame rod sensor detects the flame it powers the
modulating gas system. This is the normal operating mode. The FSC continues to monitor the flame and
airflow. Once this occurs, the unit is in a main flame cycle and thus powers the main gas valve and the
modulating gas system. This is the normal operating mode. The FSC continues to monitor the flame and
airflow. If the flame fails to light after 15 seconds of sparking, the FSC goes in to lock-out mode. Anytime
this occurs, the problem must be diagnosed and corrected to avoid future lockouts after resetting. To
begin troubleshooting, or to reset the FSC, shut down power to the heater and restart the heater. This
will clear the alarm from the flame safety.