Suburban DD-17DSI User manual

DD-17DSI • DD-17DSIW
NT-12S/SE • NT-16S/SE • NT-20S/SE
NT-24SP • NT-30SP • NT-34SP
NT-40
P-30S/40
SF-20 • SF-25 • SF-30 • SF-35 • SF-42
SF-20F • SF-25F • SF-30F • SF-35F • SF-42F
SH-35 • SH-42
SH-35F • SH-42F
SHD-2542
SFV-35 • SFV-42
SFV-35F • SFV-42F
SUBURBAN MANUFACTURING COMPANY
676 Broadway Street
Dayton, Tennessee 37321
423-775-2131
Fax: [phone]
www.rvcomfort.com
[e-mail]
Suburban
RV FURNACES
SERVICE MANUAL

2
TABLE OF CONTENTS
Page
GeneralServiceInformation...........................................................3
FurnaceSpecSheet.................................................................4
Installation ........................................................................5
VentAssemblyIllustrations ........................................................ 6-16
ReturnAirIllustrations ..............................................................16
DuctingIllustrations ................................................................17
Installation Requirements (DD, NT and P Model Furnaces) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Installation Requirements (SF, SH and SHD-2542 Model Furnaces) . . . . . . . . . . . . . . . . . . . . . . . . . . 19
InstallationRequirement(SFVModelFurnaces) ..........................................20
Furnace Specifications (DD, NT and P Model Furnaces) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Furnace Specifications (SF, SFV, SH, and SHD-2542 Model Furnaces) . . . . . . . . . . . . . . . . . . . . . . . 22
Sequence of Operation (Time Delay Relay Equipped Furnaces) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Sequence of Operation (Fan Control Module Board (520820) Equipped Furnaces) . . . . . . . . . . . . . . . 24
Sequence of Operation (24 VAC Fan Control Module Board (520947) . . . . . . . . . . . . . . . . . . . . . . . . . 25
SequenceofOperation(SHD-2542Furance) ............................................26
Trouble Shooting Flow Chart (Furnaces Equipped with Time Delay Relay) . . . . . . . . . . . . . . . . . . . . . 27
Trouble Shooting Flow Chart (Furnaces Equipped with Fan Control Module Board) . . . . . . . . . . . . . . 28
Service Hints, Diagnosis and Corrective Measures
for Suburban 24-Volt AC Electronic Ignition Furnaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-30
WiringDiagrams................................................................ 30-34
FurnaceRemoval ............................................................... 35-36
SF, SH and SHD-2542 Electrode Gap Specifications & Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
NT and Park Model Electrode Gap Specifications & Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Maintenance ......................................................................39
Cautions&SafetyInformation ................................................ Back Cover
NOTE: Our service technicians are available to assist you in making repairs or parts replacements
from 8:00 a.m. to 5:00 p.m. Eastern Standard Time, Monday through Friday (except holidays), by
calling 423-775-2131 extension 7102. E-mail address: [e-mail]

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GENERAL SERVICE INFORMATION
Suburban DYNATRAIL furnaces installed in recreational vehicles are classified as Direct Vent Sealed Combustion
Furnaces. A forced draft furnace utilizes a sealed combustion chamber which is vented to the outside atmosphere.
The intake air for combustion is also taken from outdoors and is completely isolated from the room air. A motor is used
to drive an impeller wheel to draw intake air into the chamber to support combustion and force the exhaust gases
through the furnace chamber to the outside atm osphere. A second impeller wheel (driven by the same motor yet totally
isolated from the combustion air) is used to circulate room air across the furnace chamber where it is heated. The
blower then forces the hot air into the living area either through a duct system or through a front grille on the furnace
cabinet on direct discharge models.
Suburban furnaces operate on 12-volt DC power which is supplied either by a 12-volt battery or a converter system.
A recreational vehicle furnace that is specifically designed for “park model” trailers operates on 120 volts AC. These
are designed and tested under the same standards as the 12-volt models.
Suburban forced draft combustion furnaces used in recreational vehicles are designed for use with Propane gas.
Although a few recreational vehicle furnaces are approved for use with natural gas, one should never attempt to
convert such a unit to natural gas unless the conversion is approved by the manufacturer of the furnace.
Gas Supply Pressure Requirements
Line Pressure:
Minimum 11" W C*, Maximum 14" W C
*WC - water column
Voltage Requirements
Voltage DC: 12 volt D.C.
Minimum 10.5 volts D.C., Maximum 13.5 volts D.C.
Service Tools Required
Manometer gauge/ U-Tube
Volt ohm meter capable of testing above 15 amps
Module board tester #641511
Gas leak detector OR approved leak check liquid
Assorted wrenches
Assorted hand tools
Safety glasses

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Suburban
RV FURNACES
12 VDC Direct BTU/h Shipping
Discharge Input Height Width Depth Ignition Weight
NT-12SE 12,000 9 3/8" 9 3/8" 21-27 3/4" Electronic 27
NT-16SE 16,000 9 3/8" 9 3/8" 21-27 3/4" Electronic 27
NT-20SE 19,000 9 3/8" 9 3/8" 21-27 3/4" Electronic 27
DD-17DSI 17,000 12" 10 1/2" 22-29" Electronic 25
Accessories Description
260197 Vent Kit 2" - 4" DD Models
260198 Vent Kit 4" - 6" DD Models
260199 Vent Kit 6" - 9" DD Models
12 VDC Ducted BTU/h Shipping
Furnaces Input Height Width Depth Ignition Weight
NT-12S 12,000 9 3/8" 9 3/8" 22 3/4-29 1/2" Electronic 27
NT-16S 16,000 9 3/8" 9 3/8" 22 3/4-29 1/2" Electronic 27
NT-20S 19,000 9 3/8" 9 3/8" 23 3/8-30 1/8" Electronic 27
NT-24SP 24,000 12 1/2" 12" 23" Electronic 40
NT-30SP 30,000 12 1/2" 12" 23" Electronic 40
NT-34SP 34,000 12 1/2" 12" 23" Electronic 40
NT-40 40,000 12 1/2" 12" 23" Electronic 42
SF-20F 20,000 7 1/2" 17" 20" Electronic 35
SF-25F 25,000 7 1/2" 17" 20" Electronic 35
SF-30F 30,000 7 1/2" 17" 20" Electronic 35
SF-35F 35,000 7 1/2" 17" 20" Electronic 35
SF-42F 40,000 7 1/2" 17" 20" Electronic 35
SH-35F 35,000 9 1/4" 17" 20" Electronic 40
SH-42F 40,000 9 1/4" 17" 20" Electronic 42
SF-20* 20,000 7 1/2" 17" 20" Electronic 35
SF-25* 25,000 7 1/2" 17" 20" Electronic 35
SF-30* 30,000 7 1/2" 17" 20" Electronic 35
SF-35* 35,000 7 1/2" 17" 20" Electronic 35
SF-42* 40,000 7 1/2" 17" 20" Electronic 35
SH-35* 35,000 9 1/4" 17" 20" Electronic 40
SH-42* 40,000 9 1/4" 17" 20" Electronic 42
SHD-2542 25/40,000 9 1/4" 17" 20" Electronic 44
Accessories Description
6258ACW *Door, Optional Access, Colonial White, Standard SF Models
6258APW *Door, Optional Access, Polar White, Standard SF Models
6267ACW *Door, Optional Access, Colonial White, Standard SH Models
120 VAC Park BTU/h Shipping
Model Furnaces Input Height Width Depth Ignition Weight
P-40 40,000 12 1/2" 12" 23" Electronic 46
Accessories Description
050733 Duct Cover
050715 Duct Collar 4"
051240 Duct Collar 2"
280552 Rain Shield
062164 Bottom Duct Gasket, NT-24/30/34SP, NT-40, P40
070853 Bottom Duct Gasket, SF Models Except SF-42, (F)
520009 Bottom Duct Kit W/Gasket, NT-24/30/34SP, NT-40. P40
520576 Bottom Duct Kit W/Gasket, SF Models Except SF-42, (F), SH35 (F)
520753 Bottom Duct Kit W/Gasket and Door, SF-42, (F)
520864 Bottom Duct Kit W/Gasket SH-42 (F) SHD-2542
Wall Thermostats are included with All Models, except SF.
Vent Assemblies are included with all units, except DD.

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Figure 1
INSTALLATION
There are several important aspects of the installation which will pertain to all Suburban forced draft furnaces, regardless of the model or the
method in which they are installed. They are:
1. Selecting a Location
2. Venting
3. Return Air
4. Ducting
Refer to the furnace installation manual for all installation requirements.
Location and Installation- Locate the furnace near lengthwise center of the coach. Choose a location for installation out of the way of wires,
pipes, etc. which might interfere with the installation. Adhere to the minimum clearances from cabinet to combustible construction as
listed in the installation manual for your specific furnace model. Secure furnace cabinet to the floor of the coach using the holes
provided in the furnace cabinet.

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Figure 2
SF
Figure 2A
SH
VENTING
Venting- By definition of a Direct Vent Sealed Combustion Furnace, it must be vented to the outside atmosphere and also draw combustion air
from outdoors. Therefore, it is imperative that the vent be unobstructed and there must be a seal between the exhaust and intake (caulking) . Refer
to the vent assembly installation in the manual. The vent must be straight. There can be no offsets or turns in the vent. All vent tubes which
connect to the furnace exhaust and intake must overlap a minimum of 1/2" on intake, and 1 1/4" on exhaust. Check your furnace model
number for vent installation procedures. Vents cannot be altered as supplied from the factory.
VENT ASSEMBLY INSTALLATION (SF and SH SERIES)

7
Figure 3
SF
Figure 3A
SH and SHD-2542
VENT ASSEMBLY INSTALLATION (SF and SH SERIES)

8
Figure 4
SF
Figure 4A
SH
VENT ASSEMBLY INSTALLATION (SF and SH SERIES)

9
Figure 5
Figure 5A
VENT ASSEMBLY INSTALLATION (SFV)

10
Figure 6
Figure 6A

11
Figure 7
VENT ASSEMBLY INSTALLATION (DD SERIES)
Note: Vent cap must be installed on DD furnace when bench testing.

12
Figure 10
NT-12/16S
Figure 8
NT-12/16/20SE
Figure 9
NT-12/16/20S and SE
VENT ASSEMBLY INSTALLATION (NT SERIES)

13
Figure 11
NT-20S
Figure 12
NT-24/30/34SP
P-30S
VENT ASSEMBLY INSTALLATION (NT SERIES)

14
EXTENSION TUBE
KIT NUMBER
MIN./MAX. LENGTH
(Extension Tube Range)
520593 2-1/4" to 3-1/8"
520594 3-1/8" to 4-7/8"
520595 4-7/8" to 7"
520596 7" to 9"
Figure 15
NT-40
P-40
Figure 13
NT-24/30/34SP
P-30
EXTENSION TUBE
KIT NUMBER
MIN./MAX. LENGTH
(Extension Tube Range)
520498 2-1/4" to 3-1/8"
520499 3-1/8" to 4-7/8"
520500 4-7/8" to 7"
520501 7" to 9"
Figure 14
NT-24/30/34SP
P-30S
VENT ASSEMBLY INSTALLATION (NT SERIES)

15
Figure 17
P-40
Figure 16
NT-40
VENT ASSEMBLY INSTALLATION (NT-40 and P-40)

16
Figure 19
Figure 18
NT-40
P-40
*THE TOTAL, FREE, UNOBSTRUCTED RETURN AIR OPENING
TO THE FURNACE MUST NOT BE LESS THAN THE MINIMUM
RETURN AIR
Return Air - The cabinet that the furnace may be installed in will have louvers or openings for the return air back to
the furnace. When the furnace is installed, it is imperative that the return air louvers on the furnace cabinet opening
are not obstructed.
Usually, these furnaces are installed under a counter, sofa or bed in order to be out of the way. A grille or opening must
be built into the cabinetry or into the base area of the sofa or bed. Return air from the living area of the trailer is drawn
in through the grille and into the return air openings in the furnace cabinet. Figure 19 illustrates the return air circulation
of the furnace. Note: Refer to the installation manual for the minimum return air area for your specific furnace
model.
Insufficient return air will cause the furnace to overheat and cycle on limit. Another symptom of a return air problem
is:
1. Furnace seems to run continuously in an effort to satisfy the thermostat.

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Figure 20
DUCTING
Ducting - Suburban furnaces require that a minimum duct area be maintained throughout entire duct system including
through the register. It is very important to adhere to the minimum duct area in order to keep the furnace from cycling
on high limit and to assure proper operation of the sail switch (sometimes referred to as a microswitch.) NOTE: (Refer
to the installation manual for the minimum ducted square inches area for each model.)
NOTE: Ducts terminating in a dead air space (like holding tank compartments or cargo areas (Toy Boxes) with
no means for return air recirculation should not be counted in the required duct area. Also, ducts 2" in
diameter or smaller should not be counted in the required duct area.
W hen installing a duct system, avoid making a lot of turns. The straighter the duct system, the less the resistance to
air flow and the better the performance of the furnace.
Avoid making sharp turns in the duct system. Sharp turns will increase the static pressure in the plenum area of the
furnace and could cause the furnace to cycle on limit.
The duct connections to the furnace cabinet should be tight to eliminate any heat loss which could result in overheating
of the component parts on the furnace as well as a reduction in the heated air flow through the ductwork.

INSTALLATION REQUIREMENTS
Models Clr Front Clr
Top
Clr
Btm
Clr
Back
Clr
Left
Clr
Right
Ducts Req’d Btm Duct
Sq Inch
Top Duct
Sq Inch
L & R Side Duct
Sq Inch
Return Air
Sq inch
DD-17DSI See *1 0" 0" 0" 0" 0" n/a n/a n/a n/a n/a NT-12S 3/8" 1" 0" 0" 1" 1" 2-4" n/a n/a 25" 55" NT-16S 3/8" 1" 0" 0" 1" 1" 2-4" n/a n/a 25" 55" NT-20S 1" 1" 0" 0" 1" 1" 2-4" n/a n/a 25" 55" NT-12SE See *1 5/8" 0" 0" 5/8" 5/8" n/a n/a n/a n/a n/a NT-16SE See *1 5/8" 0" 0" 5/8" 5/8" n/a n/a n/a n/a n/a NT-20SE See *1 5/8" 0" 0" 5/8" 5/8" n/a n/a n/a n/a n/a NT-24SP 0" 0" 0" 0" 1" 1" 3-4" 48" n/a 36" 55" NT-30SP 0" 0" 0" 0" 1" 1" 3-4" 48" n/a 36" 55" NT-34SP 0" 0" 0" 0" 2" 2" 4-4" 48" n/a 48" 55" NT-40 1" 1" 0" 0" 2" 2" 4-4" 48" n/a 48" 113" P-30 0" 0" 0" 0" 1" 1" 4-4" 48" n/a 48" 55" P-40 1" 1" 0" 0" 2" 2" 4-4" 48" n/a 48" 113"
*1 - Special clearances for discharge grills. Refer to Installation and Instruction Manual. *2 - Return air should be 142" if 4 ducts are used. May be reduced to 88" if 5 ducts are used. NOTE: 0" clearance is to spacer (flanges)

INSTALLATION REQUIREMENTS
Models Clr Front Clr
Top
Clr
Btm
Clr
Back
Clr
Left
Clr
Right
Ducts Req’d Btm Duct
Sq Inch
Top Duct
Sq Inch
L & R Side Duct
Sq Inch
Return Air
Sq inch
SF-20/20F 1" 0" 0" 0" 0" 0" 2-4" 56" 56" 25" 55" SF-25/25F 1" 0" 0" 0" 0" 0" 3-4" 56" 56" 36" 55" SF-30/30F 1" 0" 0" 0" 0" 0" 3-4" 56" 56" 36" 55" SF-35/35F 1" 0" 0" 0" 0" 0" 4-4" 56" 56" 48" 55" SF-42/42F 1" 1" 0" 0" 2" 2" 4-4" 72" SEE *3 56" 48" SEE *2 SH-35 1" 0" 0" 0" 1" 1" 4-4" 56" 56" 48" 55" SH-42 1" 1" 0" 0" 2" 2" 4-4" 72" SEE *3 56" 48" See *2 SHD-2542 1" 1" 0" 0" 2" 2" 4-4" 72" SEE *3 56" 48" SEE *2
NOTE: 0" clearance is to spacer (flanges) *1 - Special clearances for discharge grills. Refer to Installation and Instruction Manual. *2 - Return air should be 142" if 4 ducts are used. May be reducted to 88" if 5 ducts used. *3- Bottom duct required. SF42 uses kit # 520753, SH-42 and SHD-2542 uses kit #520864.

INSTALLATION REQUIREMENTS
Models Clr Front Clr
Top
Clr
Btm
Clr
Back
Clr
Left
Clr
Right
Ducts Req’d Btm Duct
Sq Inch
Top Duct
Sq Inch
L & R Side Duct
Sq Inch
Return Air
Sq inch
SFV-20/20F 1" 1" 0" 0" 1" 1" SEE *4 52" SEE *4 SEE *4 55" SFV-25/25F 1" 1" 0" 0" 1" 1" SEE *4 52" SEE *4 SEE *4 55" SFV-30/30F 1" 1" 0" 0" 1" 1" SEE *4 52" SEE *4 SEE *4 55" SFV-35/35F 1" 1" 0" 0" 1" 1" SEE *4 52" SEE *4 SEE *4 55" SFV-42/42F 1" 2" 0" 0" 1" 1" SEE *4 52" SEE *4 SEE *4 142"
NOTE: 0" clearance is to spacer (flanges) *1 - Special clearances for discharge grills. Refer to Installation and Instruction Manual. *2 - Return air should be 142" if 4 ducts are used. May be reducted to 88" if 5 ducts used. *3- Bottom duct required. SF42 uses kit # 520753, SH-42 and SHD-2542 uses kit #520864. *4- Vertical mount furnace review table below for ducting requirements. The duct requirements must be followed in order to assure proper operation of the furnace. The minimum open duct areas listed below must be maintained through the entire duct system including through register.
MODEL
TOP AND FRONT
DUCTS
(4" Round)
BOTTOM LEFT
DUCT
RIGHT
DUCT
Minimum
Duct Area
Minimum
Duct Area
Minimum
Duct Area
SFV-20(F) *Optional Required 52
SQ. IN.
*Optional *Optional
SFV-25(F) *Optional Required 52
SQ. IN.
*Optional *Optional
SFV-30(F) *Optional Required 52
SQ. IN.
*Optional *Optional
SFV-35(F) 48 SQ. IN. (Bottom
Front Duct Not To be
Used)
52 SQ. IN. 56 SQ. IN.
SFV-42(F) 48 SQ. IN. (Top Front
Duct Not To Be
Used.)
52 SQ. IN. 56 SQ. IN. 72 SQ. IN.
*Use of these ducts are in addition to the required use of the bottom duct.