Atwood Mobile Products 7920-II, 7916-II Standard Furnace Installation, Furnace / Vent Cutouts FIG

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Spacing of 1/4˝ to ducting within 3 feet of furnace must be provided unless UL listed wire bound vinyl ducts are used. All ducting material should be rated for continuous use of 200˚F.

NOTE: If zero clearance is maintained from furnace to cabinet structure, a 4˝ x 4˝ air intake cutout must be provided to blower wheel side of furnace at air intake opening.

NOTE: Clearances are specifically for plywood or similar building materials surrounding the furnace (i.e. furnace should NOT be located under furniture or in a closet space where clothing or other material could be located.)

NOTE: Furnace efficiency rating is a thermal rating determined under continuous operating conditions, independent of any installation. Eff. rate is given at 77% minimum, actual efficiency rating may be higher.

*When furnaces are installed to minimum clearances, an additional 16 in2 of return air must be provided to blower side of furnace, or a 2˝ clearance the full length and height on blower side must be maintained.

￿WARNING

CARBON MONOXIDE POISONING

Furnace must be installed and vented to these instructions.

Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage.

Improper installation location may cause furnace to produce negative pressure, affecting combustion air or venting of other appliances.

￿CRITICAL INSTALLATION WARNINGS

DO NOT install furnace on material that restricts return air, like carpet or any soft material such as vinyl.

DO NOT install where clearance to combustibles cannot be maintained.

DO NOT modify furnace in any way.

DO NOT alter furnace for a positive grounding system.

DO NOT HI-POT furnace unless electronic ignition system (circuit board) has been disconnected.

DO NOT use battery charger to supply power to DC model furnace even when testing.

DO NOT use 120 volt AC current with DC models.

DO NOT use furnace cabinet area as a storage compartment.

DO NOT vent furnace with venting system serving another appliance.

DO NOT vent furnace to an outside enclosed porch area.

DO NOT use for temporary heating of buildings or structures under construction.

Protect building materials from degrading from flue gas exhaust.

Protect furnace electrical components from water.

USA AND CANADA - FOLLOW ALL APPLICABLE STATE AND LOCAL CODES -

IN THE ABSENCE OF LOCAL CODES OR REGULATIONS, REFER TO CURRENT STANDARDS OF:

Recreation Vehicles ANSI 1192/NFPA 1192.

National Fuel Gas Code ANSI Z223.1 /CAN/CGA B149 Installation Codes

Federal Mobile Home Construction & Safety Standard, Title 24 CFR, part 3280, or when this Standard is not applicable, the Standard for Manufactured Home Installations (Manufactured Home Sites, Communities and Set-Ups), ANSI A255.1 and/or CAN/CSA-Z240 MH Series, Mobile Homes.

Ground - National Electrical Code ANSI/NFPA No. 70 and/or CSA C22.1

Park Trailers ANSI 119.5

NOTE: The direct high voltage spark ignition generates a radio frequency that could cause interference with other microprocessor based equipment. Locate equipment at least five feet from furnace location. If this distance can- not be maintained, purchase KIT MPD 37773 (a shielded high voltage lead).

￿WARNING

CARBON MONOXIDE POISONING

Properly seal vent cap to side wall to prevent carbon monoxide from entering coach.

DO NOT draw combustion air from living area. DO NOT vent exhaust air into the living area or an enclosed porch.

Return air is supplied through openings in furnace grille. The return air passage must be kept clear for furnace to function properly. Refer to MINIMUM CLEARANCE

TO FLOORBOARDS, WALLS & SIMILAR COMBUSTIBLE BUILDING MATERIAL.

STANDARD FURNACE INSTALLATION

General Installation - LOCATION

Install extension box and vent cap through an exterior wall.

DO NOT install furnace near tilt-out rooms, slide-outs, doors or other projections that could obstruct furnace exhaust.

Locate furnace near midpoint of coach for single furnace applications.

DO NOT install vent in areas where projections or door openings come within 6˝ of vent tube opening.

DO NOT install furnace in an area where wires, pipes, or other objects will interfere with installation or operation of furnace.

It is not recommended to install furnace on material that restricts return air, such as directly on carpet, or soft material (like vinyl).

If you must install furnace on carpet or soft material, install furnace on cleats, or on a wood or metal panel extending the full width and depth of furnace plus minimum clearances to combustibles.

Installation Procedure

 

 

 

ZERO CLEARANCE - AIR INTAKE CUTOUT

(FIG 1)

 

AIR INTAKE OPENING SIDE OF THE BLOWER WHEEL

 

 

 

 

 

 

 

CUT OUT DIMENSION

A

B

C

D

CABINET WALL

2-3/4˝

3-5/8˝

A 4˝ x 4˝ cabinet cut out must be provided when there is zero clearance between furnace and cabinet structure.

1.Set aside combustion air box and exhaust tube extensions for instal- lation from outside coach.

FURNACE / VENT - CUTOUTS (FIG. 2)

CUT OUT DIMENSION

A

B

 

INTERIOR CABINET WALL

8-3/8˝

11-1/4˝

 

DO NOT OVERSIZE HOLE - OVERSIZING CAN RESULT IN WATER LEAKAGE

 

 

 

 

CUT OUT DIMENSION

C

D

E

COACH EXTERIOR WALL FOR VENT

4-7/8˝

2-1/2˝

1-3/4˝

DUCTING (FIG. 3)

Proper duct installation is critical to operation of furnace. When installing ducts, use materials rated for continuous use at 200˚F. Front discharge temperature should not exceed 250˚F.

Flexible Ducting System

When designing Flexible Duct Systems:

avoid sharp bends or crushed ducts

stretch all ducts and run them directly to outlets, keeping quantity and angles of bends to a minimum

2.A variety of vent kits are available to provide the correct venting from fur- nace to outside of vehicle. To determine VENT LENGTH (V DIM), measure the distance from the back of furnace casing to outside vehicle side wall. For proper vent kit check your V DIM on VENTING CHART.

3.Ducting available:

TYPE OF DISCHARGE

REMOVE

SIDE ONLY

duct covers from both sides

COMBINATION

front discharge cover plate

FRONT & SIDE

and side duct cover plate

FRONT ONLY

front discharge cover plate

See DUCTING CONFIGURATIONS for covers and their locations.

4.Install the furnace through cutout in cabinet area. Secure furnace with two screws FIG 5-A.

OPTIONAL - Installation: The 79-II furnace may be installed in a

cabinet behind a return air grille FIG 4-I. Door MUST be on furnace.

2Return air grille must supply a minimum of 35 in2 of open area and

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Contents What to do if YOU Smell GAS IndexFurnace / Vent Cutouts FIG Standard Furnace InstallationCritical Installation Warnings Ducting FIGVenting System ChecksVenting Chart Diagnostic ChartHydro flameTM