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Mortex Products, Inc. / FT. WORTH, TX 76106  

G17 / G18 Installation Instructions  

Printed 04/04

16

Mortex Products, Inc. / FT. WORTH, TX 76106  

G17 / G18 Installation Instructions  

Printed 04/04

SEALED COMBUSTION
DOWNFLOW 
GAS FURNACE

FOR INSTALLATION IN:

MANUFACTURED (MOBILE) HOMES,

RECREATIONAL VEHICLES, PARK MODELS, MODULAR HOMES AND 
BUILDINGS

CAUTION:  READ ALL SAFETY GUIDES 
BEFORE INSTALLING THIS FURNACE

Contents   

Page

General Information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Specifications  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Safety Considerations  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Installation Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
High Altitude Installation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Installation Clearances  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Return Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
Alcove & Closet Installations  . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Air Distribution  Systems  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Duct Connector/Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Install Furnace   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Roof Jack Selection  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Cut Openings & Install Roof Jack . . . . . . . . . . . . . . . . . . . . . . . .8
Installing in Snow Regions  . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Roof Jack On Hi-Pitch Roof . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Transit-mode Roof Jack  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-9
Connect Power Supply Wires  . . . . . . . . . . . . . . . . . . . . . . . . . .9
Wall Thermostat  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Connect Thermostat Wires  . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Gas Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-10
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-13
Repair Parts List  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14-15
Final Procedure  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Furnace and Air Conditioner Installations  . . . . . . . . . . . . . . . . .16
High Altitude Deration Chart  . . . . . . . . . . . . . . . . . . . . . . . . . .16

GENERAL INFORMATION

These downflow sealed combustion furnaces install in
Manufactured Homes, Recreational Vehicles or modular 
construction. The furnaces conform to Part 3280 (a) (2) of HUD
Manufactured Home Construction and Safety Standards. They
must be installed only with listed RJ-Roof Jack, sealed 
combustion venting system. 

NOTE: These instructions are intended to assist qualified 
individuals experienced in the installation of heating equipment.
Some state and local codes require installation personnel to be
licensed. Read all instructions before starting the installation.

SAVE THIS MANUAL 

NOTICE

- A furnace set-up and any adjustment needed is the

responsibility of the installer/retailer/contractor and is not 
covered by the furnace manufacturers warranty.

CHECKLIST: FURNACE START-UP

1.  Has furnace roof jack crown been correctly installed?
2.  Has the furnace gas valve and burner orifice been correctly 

converted to L.P. Gas where applicable?

3.  Is the gas line outlet pressure set for the fuel used?

NAT Gas is 3.5” W.C. and  L.P. Gas is 10.0”W.C.

4.  If the home uses a crossover air connector duct, is it installed

per the homebuilders installation instruction?

5.  Has the furnace been operated through a complete 

heating cycle?

INSTALLATION INSTRUCTIONS

FINAL PROCEDURE

INSTALL FURNACE DOOR PANELS

A. Install the lower door panel by engaging 2 tabs on 
bottom cabinet pan into slots on plastic end cap.  Then,
push in top of door panel until clips on the center divider
panel are engaged with latches on door.

B. Install the upper louver door panel in a similar manner,
by first engaging  tabs on the center divider and then 
pushing the panel in to engage the clips at top of the 
cabinet.

FINISH AND TRIM

The alcove or closet installation may be finished and
trimmed out as needed.

AIR CONDITIONING SYSTEMS 

If an air conditioning system is installed which does not use
the blower for air distribution and operates completely 
independent of the furnace, the thermostat system shall
include interlock, which prevents simultaneous operation of
the furnace and air conditioner.  An interlock system 
typically contains a switch, which must be turned to either
HEAT or COOL to activate either heating or cooling 
operation. A cooling thermostat may include a positive OFF
switch for this purpose. 

When used in connection with a cooling unit the furnace
shall be installed parallel with or on the upstream side of
the cooling unit to avoid condensation in the heat 
exchanger. For installations with a parallel flow 
arrangement, the furnace must be equipped with a damper
or other means to prevent cold air from being discharged
up around the heat exchanger.

GAS VALVE CONVERSION INSTRUCTIONS

1. Follow instructions “TO TURN OFF GAS TO APPLIANCE”
2. Remove two bolts securing the gas valve bracket. Pull gas valve

valve bracket and burner orifice holder exposing the main burner orifice. 

3. Install burner orifice specified on the rating plate for the desired gas.

Conversion parts are in a bag attached to the gas valve.

4. Replace valve, bracket/orifice holder, and bolts.

Attach ID tag for the desired gas adjacent to the gas valve.
Ensure that all connections are tight.

5. Unscrew and reverse the pressure regulating cap so the name of the 

desired gas is closest to the valve. See illustration.

HIGH ALTITUDE DERATE CHART- MAIN BURNER ORIFICE SIZE

NATURAL GAS

ELEVATION

60,000 BTUH FURNACE

70,000 BTUH  FURNACE

75,000 BTUH  FURNACE

90,000 BTUH FURNACE

PART NO

ORIF DIA.  DRILL SIZE

PART NO

ORIF DIA. DRILL SIZE

PART NO

ORIF DIA. DRILL SIZE

PART NO

ORIF DIA.

DRILL SIZE

SEA LEVEL

72AG-147

0.1470

26

72AG-159

0.1590

21

72AG-161

0.1610

20

72AG-180

0.1800

15

2,000

72AG-144

0.1440

27

72AG-154

0.1540

23

72AG-161

0.1610

20

72AG-177

0.1770

16

3,000

72AG-140

0.1405

28

72AG-154

0.1540

23

72AG-159

0.1590

21

72AG-173

0.1730

17

4,000

72AG-140

0.1405

28

72AG-152

0.1520

24

72AG-157

0.1570

22

72AG-173

0.1730

17

5,000

72AG-140

0.1405

28

72AG-149

0.1495

25

72AG-154

0.1540

23

72AG-169

0.1690

18

6,000

72AG-136

0.1360

29

72AG-147

0.1470

26

72AG-152

0.1520

24

72AG-166

0.1660

19

7,000

72AG-136

0.1360

29

72AG-144

0.1440

27

72AG-149

0.1490

25

72AG-161

0.1610

20

8,000

72AG-128

0.1285

30

72AG-140

0.1405

28

72AG-147

0.1470

26

72AG-161

0.1610

20

9,000

72AG-128

0.1285

30

72AG-140

0.1405

28

72AG-144

0.1440

27

72AG-157

0.1570

22

10,000

72AG-128

0.1285

30

72AG-136

0.1360

29

72AG-140

0.1405

28

72AG-152

0.1520

24

LP-PROPANE GAS

ELEVATION

60,000 BTUH FURNACE

70,000 BTUH  FURNACE

75,000 BTUH  FURNACE

90,000 BTUH FURNACE

PART NO

ORIF DIA. DRILL SIZE

PART NO

ORIF DIA. DRILL SIZE

PART NO

ORIF DIA. DRILL SIZE

PART NO

ORIF DIA.

DRILL SIZE

SEA LEVEL

72AG-089

0.0890

43

72AG-099

0.0995

39

72AG-101

0.1015

38

72AG-113

0.1130

33

2,000

72AG-086

0.0860

44

72AG-098

0.0980

40

72AG-099

0.0995

39

72AG-110

0.1100

35

3,000

72AG-086

0.0860

44

72AG-096

0.0960

41

72AG-098

0.0980

40

72AG-110

0.1100

35

4,000

72AG-086

0.0860

44

72AG-096

0.0960

41

72AG-096

0.0960

41

72AG-106

0.1065

36

5,000

72AG-082

0.0820

45

72AG-093

0.0930

42

72AG-096

0.0960

41

72AG-106

0.1065

36

6,000

72AG-082

0.0820

45

72AG-093

0.0930

42

72AG-093

0.0930

42

72AG-104

0.1040

37

7,000

72AG-081

0.0810

46

72AG-089

0.0890

43

72AG-093

0.0930

42

72AG-101

0.1015

38

8,000

72AG-078

0.0780

47

72AG-089

0.0890

43

72AG-089

0.0890

43

72AG-101

0.1015

38

9,000

72AG-078

0.0780

47

72AG-086

0.0860

44

72AG-089

0.0890

43

72AG-098

0.0980

40

10,000

72AG-076

0.0760

48

72AG-086

0.0860

44

72AG-086

0.0860

44

72AG-096

0.0960

41

Reference: NFPA No. 54, ANSI Z 223.1 National Fuel Gas Code
Table shows 4% Input Reduction per 1,000 feet elevation.
For Canadian High Altitude (2,000-4,500 feet), reduce gas pressure to burner manifold (manifold Ps.) to 3.0" W.C., and 9.0" W.C. for LP (Propane) Gas

G17D, G18D

Sizes 060-090

WARNING-RISK OF FIRE OF ELECTRICAL SHOCK

Only qualified service personnel shall be used to install
and provide maintenance of this furnace. 

P/N: 61GF0011

Summary of Contents for G17D

Page 1: ...th a cooling unit the furnace shall be installed parallel with or on the upstream side of the cooling unit to avoid condensation in the heat exchanger For installations with a parallel flow arrangement the furnace must be equipped with a damper or other means to prevent cold air from being discharged up around the heat exchanger GAS VALVE CONVERSION INSTRUCTIONS 1 Follow instructions TO TURN OFF G...

Page 2: ...n 6 PART NO DESCRIPTION NOTES 90 RJF1729 AL Body Roof Jack Gas FLAT Height A 73 in 85 in 90 RJF2551 AL Body Roof Jack Gas FLAT Height A 81 in 107 in 90 RJS1729 AL Body Roof Jack Gas SLOPE 3 12 Height B 81 in 101 in 90 RJS2551 AL Body Roof Jack Gas SLOPE 3 12 Height B 97 in 123 in 90 RJS3868 AL Body Roof Jack Gas SLOPE 3 12 Height B 110 in 140 in 90 RJS6399 AL Body Roof Jack Gas SLOPE 3 12 Height B...

Page 3: ...stem have a flame spread classification of 200 or less 6 Non combustible pans having one inch upturned flanges are located beneath openings in the floor return duct system 7 Wiring materials located in the return duct system conform to Article 300 22 B C of the National Electric Code ANSI NFPA 70 8 Gas piping is not run in or through the return duct system 9 The negative pressure in the closet as ...

Page 4: ...ng above the floor Bend sides over onto the floor surface Fig F 8 Install floor base over floor opening with 13x13 flanges down Nail to floor thru 4 holes Fig G INSTALL FURNACE Prior to installing furnace fuel and A C line openings may be cut in See FIG D 1 Remove upper and lower furnace doors 2 Slide furnace onto floor base and push back until cabinet is against rear flange of floor base 3 Secure...

Page 5: ...es gas line connection point To furnace gas control valve To furnace wall thermostat 4 Upper crown in original carton must be stored in a prominent location inside the home until crown installation is made at site location AT MANUFACTURED HOME SITE 5 The transit weather cap is removed and 6 90 RJCRWN AL crown installed per these instructions See FIG K Make sure crown engages RJ body pipes above th...

Page 6: ...ator on the gas control valve must also be converted See label on lower furnace compartment for full instructions If the gas input to the furnace is too high due to excessive gas pressure wrong size burner orifice no orifice high altitude etc the burner flame will be sooty especially with Propane gas This type of furnace operation can produce carbon monoxide which could result in unsafe operation ...

Page 7: ...ADY MODELS G17D060 G17D070 P N 61GFC004 Mortex Products Inc FT WORTH TX 76016 H 2 10 1 4 HP 2 SPD BLOWER HEATING SPEED SELECTION G17D060 G17D070 LO OR HI SPEED TAP FIG N G17D060 G17D070 W PILOT HEATING FIG O G17D060B G17D070B W PILOT A C READY FIG Q G17D090B W PILOT A C READY FIG P G17D090 W PILOT HEATING WARNING ELECTRIC SHOCK HAZARD Disconnect all electric power before servicing 1 Incoming wire ...

Page 8: ... R68CA0005 R86GF0050 R86GF0050 R68GF0001 R68GF0006 R68GF0007 R68BKN007 R86GF0051 R86GF0052 R68GF0004 R68DD0009 R68DD0009 R68DD0008 R68GF0002 R68CA0004 R86GF0053 R86GF0054 R86GF0054 R68GF0005 R76AA0002 R86GF0055 R86GF0123 R86GF0119 R65GF0001 R65GF0002 R65GF0003 R86GF0056 R68DE0001 R68DE0002 R68DE0003 R69AB0001 R68AB0002 R68AB0002 R68CA0007 R68CA0006 R68GF0009 R68GF0008 R86GF0057 R86GF0058 R87NBF007...

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