Page 4
Fan off" timings (time that the blower operates after the
heat demand has been satisfied) are determined by the arĆ
rangement of a jumper across pins on the BCC2-2 blower
control board. See figure 2. To adjust fan off " timings, gentĆ
ly disconnect jumper and reposition across pins correĆ
sponding with new timing. Fan on" time is factory set at 45
seconds and is not adjustable.
Figure 4 shows the various fan off" timings and how jumpĆ
er should be positioned. Unit is shipped with a factory fan
off" setting of 90 seconds. Fan off" time will affect comfort
and efficiency and is adjustable to satisfy individual apĆ
plications.
3-Door Interlock Switch (S51)
A door interlock switch rated 16A at 125VAC is located beĆ
hind the blower access panel. The switch is wired in series
with line voltage. When the blower door access panel is reĆ
moved the unit will shut down.
B-Blower Motors and Capacitors
All G17 units use direct drive blower motors. All motors
used are 120V permanent split capacitor motors to ensure
maximum efficiency. See table1 for ratings.
TABLE 1
G17 BLOWER RATINGS 120V 1PH
BLOWER MOTOR
HP
Q2
Q3
Q3/4
CAP
1/2
1/3
1/4
5MFD 370V
5MFD 370V
7.5MFD 370V
Q5/6
Q4
Q4/5
1/2
7.5MFD 370V
3/4
40MFD 370V
3/4
40MFD 370V
C-Blocked Vent Shutoff Switch (S62)
The blocked vent shutoff switch or spill switch (S62) is loĆ
cated on the right side of the draft diverter. The switch is a
high temperature N.C. SPST manualĆreset limit conĆ
nected in series with ignition control A3. The switch opens
when excess heat is sensed in the draft diverter. Excess
heat in the draft diverter can be caused by a blocked vent
or reversed draft (outside air coming down the flue). Limits
on early production units open at 300
_
F+12
_
F (149
°
C) on
a temperature rise. Later production units use a limit
which opens at 262
_
F+12
_
F (128
°
C). It cannot be adĆ
justed.
D-Flame Rollout Switch (S47)
Flame rollout switch is a high temperature limit located on
top of the burner box. The limit is a N.C. SPST manualĆreset
limit connected in series with the ignition control A3. When
S47 senses rollout, the ignition control immediately stops
ignition and closes the gas valve. If unit is running and flame
rollout is detected, the gas valve will close and ignition conĆ
trol will be disabled. Rollout can be caused by a reverse
draft, blocked flue or lack of combustion air. The switch is
factory set and cannot be adjusted. See table 2. The switch
can be manually reset. To manually reset a tripped switch,
push the red reset button located on the control.
TABLE 2
FLAME ROLLOUT SWITCH SETPOINTS
HEATING INPUT KBTUH
SETPOINT
50, 75
100, 125
260
°
F + 12
°
F
300
°
F + 12
°
F
E-Limit Control (S10)
The primary limit (S10) on G17 units is located in the middle of
the heating vestibule wall. When excess heat is sensed in the
heat exchanger, the limit will open and interrupt current to the
gas valve. If the limit is tripped, the BCC2-2 energizes the
blower. The limit automatically resets when unit temperature
returns to normal. Table 3 shows the temperatures at which
the limit trips on a temperature rise and then closes on a temĆ
perature fall.
TABLE 3
UNIT MODEL NO.
TEMP. RISE
TEMP. FALL
G17Q2-50 Series
G17Q3-75 Series
G17Q3/4-100 Series
G17Q5/6-100 Series
G17Q5/6-125 Series
130
°
F + 5
°
F
100
°
F + 10
°
F
180
°
F + 5
°
F
150
°
F + 8
°
F
180
°
F + 5
°
F
150
°
F + 10
°
F
250
°
F + 5
°
F
220
°
F + 8
°
F
180
°
F + 5
°
F
150
°
F + 10
°
F
PRIMARY LIMIT TEMPERATURES
INSULATING COVER (s)
FIGURE 5
G17 SERIES UNITS
LIMIT CONTROL FOR
SP
ADE CONNECT
ORS
INSULA
TING COVER
LIMIT
LIMIT
F-Robertshaw Electronic Ignition
The Robertshaw electronic ignition is an intermittent pilot
ignition control module located on the vestibule panel. See
figure 1. When there is a call for heat, the control generates
a spark to ignite the pilot, after which the control senses the
flame. If the flame current is too weak (less than 1 microĆ
amp) the control will shutdown and de-energize the gas
valve. Flame current should be between 1 and 5 microĆ
amps. See figure 6.
DANGER
Shock hazard.
Spark related components contain high voltage.
disconnect power before servicing. Control is
not field repairable. If control is inoperable, simĆ
ply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
