Atwood Mobile Products MPD 32072, 7916-II, 8012-II, 7920-II Venting, System Checks

be in front of door to furnace. Provide an access opening for service and/or removal of furnace. The furnace must be side ducted (NO front discharge). Secure furnace to floor with one screw FIG 4-J.

5.Remove cover plate from furnace FIG 4-D. To install duct adapters for side discharge models, insert back flange over casing and insert tab into square notch, then twist adapter 180˚ FIG 4-E.

6.Insert furnace into cabinet opening and secure with two screws through holes in control box flanges FIG 5-A.

7.For side duct applications, slide 4˝ flexible ducting material over duct adapters and secure FIG 3.

VENTING

1.To install extension box FIG 4-C, apply mastic or sealant to back of flanges on box. Slide through outside wall cut out and into furnace

air channel. DO NOT FORCE OR BEND PARTS.

2.Apply mastic or sealant to the top and sides of outer edge of vent cap. DO NOT PLUG HOLES. Slide assembly over furnace exhaust tube FIG 4-B, push into wall and secure with two screws. Note that bottom flange is not sealed to allow water drainage.

3.The extension box has no minimum clearance requirement FIG 4-C.

4.The vent outlet shall be installed as to be in the same atmospheric pressure zone as the combustion air intake. No modification of vent system is allowed.

￿WARNING

CARBON MONOXIDE POISONING

•Properly seal vent system preventing carbon monoxide from entering coach.

5.Install return-air system to ensure negative pressure, created by the circulating blower, does not effect another appliance’s combustion air supply or act to mix products of combustion with circulating air. All appliances in the furnace cabinet must be directly vented outside.

DIRECTIONAL AIRBOX INSERT (FIG. 7)

1.Remove front door of furnace.

2.Follow shutdown procedure instructions affixed to furnace.

3.Remove sheet metal screw holding circuit board plate to air box. Retain to fasten Air Box Insert to bottom of air box FIG 7-A.

4.Install Air Box Insert into air box (pay attention to the direction you would like warm air diverted). Make sure two holes in Air Box Insert line up with existing holes in air box FIG 7-B.

5.Fasten Air Box Insert to top of air box using a 1/4˝ long #6 sheet metal screw. Fasten bottom of Air Box Insert and circuit board plate to bottom of air box using the screw removed.

6.Follow lighting instructions to place furnace in operation.

7.Replace front door on furnace.

PROPANE GAS CONNECTION (FIG. 5)

Connect gas line to brass fitting on left side of furnace. Be sure all male pipe threads, other than flare fittings, are treated with a sealing compound resistant to the action of propane (LP) gas. DO NOT put seal- ing compound on flare fittings.

1.Insert gas line through hole on left side.

2.Connect gas line to brass fitting inside furnace casing immediately ahead of gas control valve FIG 5-B.

3.A 3/8˝ flared fitting connection is provided at gas control valve inlet for gas supply connection to furnace. The gas supply line of furnace must be of ade- quate size to provide 11˝ W.C. gas pressure. This pressure must be main- tained under maximum flow conditions with all gas appliances operating.

4.A 1/8˝ N.P.T. plug is accessible for test gauge connection on gas valve assembly FIG 5-H.

5.Use two wrenches to hold brass fitting and flare nut when tightening gas line to brass fitting. DO NOT twist valve assembly FIG 6.

ELECTRICAL CONNECTION

￿WARNING

INJURY OR PROPERTY DAMAGE

•Label all wires before disconnecting for service. Wiring errors can cause improper, dangerous operation. Verify proper operation after servicing.

•Disconnect electrical power before servicing.

Conductor Sizing Table - MAX. 10% VOLTAGE DROP - (12 VDC)

CURRENT DRAW (AMPS)
	3	4	5	6	7	8	9	10	15
GAGE	MAX. LENGTH OF SAE CONDUCTOR (IN FEET) FROM SOURCE TO DEVICE
18	61	45	36	30	26	23	20	18	12
16	96	72	58	48	41	36	32	29	19

￿CAUTION

PROPERTY DAMAGE

•This connection is for low-voltage battery or direct current only. Do not connect to 120- or 240- volts AC.

This furnace is designed for negative ground 12 volts DC only. DO NOT attempt to alter furnace for a positive ground system or connect furnace directly to 120 volts AC. Damage to furnace components will occur and warranty will be voided.

Use a minimum of 22-18 GA wire to minimize voltage drop. The furnace must be installed so electrical components are protected from water. To make electri- cal connections: SEE WIRING DIAGRAM FIG 8

1.Remove screw from junction box on right side of furnace FIG 5-B.

2.Route wiring to right side of furnace.

3.Connect red wire FIG 5-C to positive side of power supply.

4.Connect black wire FIG 5-D to grounded side of power supply.

5.Connect white wire from furnace to thermostat FIG 5-E.

6.Connect thermostat wire from thermostat to +12VDC of power supply FIG 5-F.

7.Reinstall junction box cover FIG 4-F.

For best performance of furnace when power supply is from a converter equipped with a charging port, wire the converter to furnace parallel with battery. This pro- vides consistent voltage to furnace, increasing component life, filtering power surges and AC spikes FIG 4-G & H.

NOTE: All units are supplied with a power switch which when turned off for servicing will remove power through the furnace wiring. Switch must be in ON position for the furnace to operate FIG 5-I.

THERMOSTAT INSTALLATION

The thermostat is very sensitive. HANDLE WITH CARE AT ALL TIMES. Locate thermostat 48˝ to 54˝ above floor on an INTERIOR wall away from areas of abnormal heat or cold. EXTERIOR wall location must have a 3/4˝ spacer between thermostat and exterior wall.

Follow manufacturer’s installation instruction provided with thermostat. When thermostat is not supplied, use a thermostat rated for 12 VDC or 24 VAC min. 1 AMP.

DOOR INSTALLATION

Install door by sliding door flange over control box top flange and fastening door at bottom with 1/4 turn fastener. Note: To assure sufficient return air to circulating blower maintain specified clearances.

SYSTEM CHECKS

￿WARNING

FIRE OR EXPLOSION

•Never check for leaks with an open flame.

PROPANE GAS PRESSURE TEST

The furnace and any individual shut-off valve must be disconnected from gas sup- ply piping system during any pressure testing of system at test pressures of more than 1/2 PSI.

Before furnace is connected piping systems must be tested to be leak free. The test must maintain air pressure of at least 6˝ of mercury or 3 PSI for at least 10 minutes.

The entire piping system must be maintained within a range of 10-14˝ W.C. with all appliances in operation. Test gas connections for leakage with a leak test solu- tion.

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