Lennox G17QX-50, G17Q3-100, G17Q3-75, G17Q3X-75, G17Q4-100 Unit Information
...
SERVICE
UNIT
INFORMATION
G17
Corp. 9132-L11
G17 SERIES UNITS
G17 and G17X series units are mid-efficiency gas furĆ
naces manufactured with Duracurve heat exchangers
formed of cold rolled steel. G17 units are available in heatĆ
ing capacities of 50,000 to 125,000 Btuh and cooling apĆ
plications up to 6 tons. Refer to Engineering Handbook for
proper sizing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LPG operation. All G17 and
G17X units use electronic (intermittent pilot) ignition. The
G17X unit meets the California Nitrogen Oxides (NO
x
Standards and California Seasonal Efficiency requireĆ
ments. G17X units use only natural gas. All units use a reĆ
dundant gas valve to assure safety shut-off as required by
A.G.A.
A burner box damper assembly located on the intake side of
the burners is featured on G17 series units. A damper door in
the burner box shuts during unit off cycles to retain heat in the
unit. A damper prove switch ensures that damper is open beĆ
fore gas valve is energized. G17 furnaces use atmospheric
burners without an induced draft motor. All G17 units use a
draft hood which allows the use of standard single wall vent
connectors.
SPECIFICATIONS
Model No.
Input Btuh
Output Btuh
*A.F.U.E.
California Seasonal Efficiency - X" Models
Flue connection (in. diameter) round
Temperature rise range
High static certified by A.G.A.(in wg.)
Gas Piping Size I.P.S. inches - Natural (**LPG)
Blower wheel nominal diameter x width (in.)
Blower motor hp
Number and size of filters (in.)
**Optional LPG Conversion Kit
Electrical characteristics
Continuous Low Speed Blower Kit (Optional)
Bottom Return Air
Filter (Optional)
Return Air Cabinet (Optional)
•Not available with LPG.
*Annual Fuel Utilization Efficiency based on D.O.E. test procedures and according to F.T.C. labeling requirements. Isolated combustion system rating for non-weatherized furnaces.
**LPG kit must be ordered extra for field changeover.
***G17Q5/6XĆ100 model furnished with 25 x 26 x 1 filter.
〈°F)
Part No.
Media Cut Size (in.)
G17Q2-50
•G17Q2XĆ50
48,000
38,000
78.0%
72.3% 73.4% 73.7% 72.5% Ć Ć Ć Ć
4
20-50
.50
1/2 (1/2)
9 x 7
1/4
1, 1-1/2, 2Tons of cooling that can be added
120 volts Ċ 60 hertz Ċ 1 phase (less than 12 amps) Ċ All Models
Ć Ć Ć Ć
Ć Ć Ć Ć Ć Ć Ć Ć Ć Ć Ć Ć
RA10Ć16Ć49
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as a recĆ
ommendation only and do not supersede or replace local
or state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommended only and do not constitute
code.
)
G17Q3-75
•G17Q3XĆ75
75,000
59,000
78.0% 78.0% 78.0% 78.0%
4556
35-65 35-65 25-55 35-65
.50 .50 .75 .50
1/2 (1/2) 1/2 (1/2) 1/2 (1/2) 1/2 (1/2)
10 x 7 10 x 8 12 x 12 12 x 12
1/3 1/2 3/4 3/4
2-1/2 or 3 5 or 6 5 or 63, 3-1/2 or 4
(1) 16 x 25 x 1
Ć Ć Ć Ć Ć Ć Ć Ć LBĆ62752DA (NonĆX Models)
RA10Ć16Ć49 RA10Ć16Ć53 RA10Ć16Ć53RA10Ć16Ć49
G17Q3/4-100
•G17Q3/4XĆ100
100,000
79,000
LB-62384DB (All Models)
LB-63646A (All Models)
G17Q5/6-100
G17Q5/6-100
•G17Q5/6XĆ100
•G17Q5/6XĆ100
100,000
79,000
***(1) 20 x 25 x 1
25 x 26 x 1
G17Q5/6-125
Litho U.S.A.
125,000
98,000
Page 1
1992 Lennox Industries Inc.
G17 PARTS IDENTIFICATION
UPPER ACCESS
PANEL
MANIFOLD
GAS VALVE
BURNER BOX
DAMPER ASSEMBLY
TOP STRIP
GAS
DRAFT
HOOD
bIGNITION
CONTROL
ROLL-OUT
SWITCH
PILOT/ELECTRODE
ASSEMBLY
BLOCKED VENT
SHUTOFF
SWITCH
BURNER BOX
BURNERS
REAR BAFFLE
HEAT
EXCHANGER
LIMIT
CONTROL
BLOWER
CABINET
CONTROL BOX
G17 CONTROL BOX
NEUTRAL
TERMINALS
INB
DAMPER
MOTOR
N1
CABN
N
XFMRN
SPEED TAP
LINE
VOLTAGE
CAB
COOLING
TERMINAL
A
L1
120VAC
CONSTANT FAN
XFMR
TERMINAL
NOT
USED
D
TRANSFORMER
BCC2 BLOWER CONTROL CENTER
24VAC
VALV E
SENSE
LIMIT W RWYTG
FIGURE 1
TOP VIEW
TERMINALS
SPEED TAP
TERMINAL
DDH
CF
270
150
210
90
24V T COM
DUMMY
HEATING
ACC
ACCESSORY
TERMINAL
BLOWER TIME
ADJUSTMENT
TRANSFORMER
GROUND
SCREW
JUMPER
DOOR
INTERLOCK
SWITCH
THERMOSTAT
CONNECTIONS
FIGURE 2
Page 2
I-UNIT COMPONENTS (Figures 1)
G17 unit components are shown in figure 1. The blower
controls, gas valve and burners can be accessed by reĆ
moving the upper access panel.
G17 units are factory equipped with bottom return air panels
and bottom side return air panels in place. The panels are deĆ
signed to be field removed as required for bottom air return or
side air return. All X models are factory equipped with the botĆ
tom return air panel removed.
DANGER
Possibility of exhaust gas recirculation.
X models are factory equipped with bottom return
air panel removed. If opening is not used and if
not properly sealed, exhaust gases can recircuĆ
late through the opening and enter supply air
stream resulting in personal injury or death.
A-Control Box Components(Figure 3)
On G17 series units the unit control box is located in the
blower compartment between the burner box and the blowĆ
er housing. The hinged control box can be lowered for serĆ
vice access by removing two securing screws, one located
on either side. At the top right corner of the control box is the
door interlock switch (S51).
Housed in the control box are the unit transformer (T1) and
BCC2-2 blower control (A15).
G17 CONTROL BOX Ć FRONT VIEW
DOOR
DAMPER
DOOR
INTERLOCK
S51
BCC2-2 is a printed circuit board which controls the blower
and monitors primary limit and gas valve operation. The
control has a non-adjustable, factory preset on" fan timĆ
ing. Fan off" timings are adjustable. The board is divided
into two sections, 120 and 24VAC. Line voltage comes into
the board on the 120VAC side. See figure 2.
CAB" and XFMR " send 120VAC to the damper motor and
transformer, respectively. The active cooling and heating
blower speed terminals and three dummy D" terminals are
located on the 120VAC side of the BCC2-2. Also located on
the 120VAC side of the control are neutral terminals and a
terminal for accessories such as an electronic air cleaner.
24VAC comes from the transformer into terminal 24V" on
the 24VAC side of the BCC2-2. Thermostat connections
and safety circuit terminals are also located on the 24VAC
side of the control. Fan off" timings may be adjusted by
changing the position of a jumper across terminal pins.
The CF" terminal provides 120VAC power for continuous
fan option or other accessories.
Later production units are equipped with a 3A fuse located
inline between the transformer and terminal XFMR on the
blower control. The fuse provides overcurrent protection
to all components located in the low voltage control circuit.
Fan Timings
DANGER
Shock hazard. Avoid control damage or personĆ
al injury. Make sure to disconnect power before
changing fan off" timings.
FANĆOFF TIME ADJUSTMENT
TIMING
JUMPER
To adjust fan-off timings:
Remove jumper from BCC2 and select
one of the other pin combinations to
achieve the desired time.
BCC2-2
CONTROL
A15
BLOWER
FIGURE 3
1- Control Transformer (T1)
A transformer located inside the control box provides powĆ
er to the low voltage section of the unit. Transformers on all
models are rated 30VA with a 120V primary and a 24V secĆ
ondary.
2- BCC2-2 Blower Control (A15)
All G17 units utilize the BCC2-2 blower control. The
TRANSFORMER
T1
Page 3
TIMING PINS
(seconds)
270
210
Leave jumper off to
achieve
330 second fan-off timing.
150 90
FIGURE 4
NOTEĊIf fan off" time is set too low, residual heat in
heat exchanger may cause primary limit S10 to trip reĆ
sulting in frequent cycling of blower. If this occurs, adĆ
just blower to longer time setting.
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
BLOWER MOTOR HP
Q2
Q3
Q3/4
Q4
Q4/5
Q5/6
G17 BLOWER RATINGS 120V 1PH
1/4 5MFD 370V
1/3
1/2
1/2 7.5MFD 370V
3/4 40MFD 370V
3/4 40MFD 370V
5MFD 370V
7.5MFD 370V
CAP
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
50, 75
100, 125
SETPOINT
260°F + 12°F
°F + 12°F
300
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
PRIMARY LIMIT TEMPERATURES
UNIT MODEL NO. TEMP. RISE TEMP. FALL
130
G17Q2-50 Series
G17Q3-75 Series
G17Q3/4-100 Series
G17Q5/6-100 Series
G17Q5/6-125 Series
INSULATING COVER
SPADE CONNECTORS
°F + 5°F 100°F + 10°F
°F + 5°F 150°F + 8°F
180
°F + 5°F 150°F + 10°F
180
°F + 5°F 220°F + 8°F
250
180
°F + 5°F 150°F + 10°F
LIMIT CONTROL FOR
G17 SERIES UNITS
LIMIT
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
LIMIT
INSULATING COVER (s)
FIGURE 5
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.
Page 4
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