Dometic Blizzard NXT H541815A Installation Instructions Manual Download Page 5

5

A.  Choosing Proper Location For Unit

This unit is specifically designed for installation on the roof 

of an RV. When determining your cooling requirements, the 

following should be considered:

 

Size of RV;

 

Window area (increases heat gain);

 

Amount of insulation in walls and roof;

 

Geographical location where the RV will be 

used;

 

Personal comfort level required.

1.  For one unit installation: The unit should be 

mounted slightly forward of center (front to back) 

and centered from side to side.

2.  For two unit installations: Install one unit 1/3 and 

one unit 2/3’s from front of RV and centered from 

side to side.

It is preferred that the unit be installed on a relatively flat 

and level roof section measured with the RV parked on a 

level surface. See table below for maximum acceptable tilt.

Model

Number

Max Tilt 

(All Directions)

H541815A

H541816A

H541915A

H541916A

H551816A

H551916A

15°

3.  After Location Has Been Selected:

a.  Check for obstructions in the area where unit 

will be installed. See (FIG. 1).

FIG. 1

Dimensions Are Nominal

Keep These Air 

Flow Areas Free 

Of Obstructions

Front

Center Line Of Unit

Roof Opening

13-7/8″

40″

30″

4″

18″

4″

INSTALLATION INSTRUCTIONS

b. 

 

Maintain structural integrity. 

Otherwise damage to product and/or RV 

could occur.
The roof must be designed to support 130 

pounds when RV is in motion. Normally 

a 200 lb. static load design will meet this  

requirement.

B.  Roof Preparation

1. 

 

FIRE OR ELECTRICAL SHOCK 

HAZARD. Make sure there are no obstacles 

(wires,  pipes,  etc.)  inside  RV’s  [roof  /  floor  / 

walls]. Shut  

OFF 

gas supply, disconnect 120 

Vac power from RV, and disconnect positive (+) 

12 Vdc terminal from supply battery  

BEFORE 

drilling or cutting into RV. Failure to obey these 

warnings could result in death or serious injury.

Opening Requirements - Before preparing 

the ceiling opening, the type of system op-

tions

 MUST 

be decided upon. Read all of 

the following instructions before beginning 

the installation.

2.  Carefully mark and cut the required roof opening. 

See "B. Roof Requirements" on page (4).

3.  Using the roof opening as a guide, cut the match-

ing hole in the ceiling.

4. 

 

Maintain structural integrity. Oth-

erwise damage to product and/or RV could oc-

cur.

 

NEVER 

create a low spot on RV 

roof. Otherwise, water will pool and could cause 

a leak.
The opening created must be framed to provide 

adequate support and prevent air from being 

drawn from the roof cavity. Framing stock 3/4″ 

or more in thickness must be used. Remember 

to provide an entrance hole for power supplies, 

indoor temperature sensor (if applicable), ther-

mostat communication cable, and furnace wires 

(if applicable) at the front of the opening. See 

(FIG. 2).

Summary of Contents for Blizzard NXT H541815A

Page 1: ...h 3316202 000_B 2017 Dometic Corporation LaGrange IN 46761 Roof Top Unit Quiet Zone Ducted Application Description Blizzard NXTTM Model Board Built In Thermostat Optional Indoor Temperature Sensor Air Conditioner CCC 2 Controls H541815A H541816A Board Built In 3314082 000 CCC 2 Blk 3314082 011 CCC 2 Wht 3311931 000 20 3311931 012 40 3311931 020 60 LCD SZ Controls H541915A H541916A Board Built In 3...

Page 2: ...SZ System Only System Checkout 16 N CCC 2 System Only Reset Checkout 16 O CCC 2 System Only Furnace Aqua Temperature Differential Setting 16 GENERAL INFORMATION 17 A Heat Gain 17 B Condensation 17 WIRING DIAGRAMS 18 A Simple RV Wiring Diagram 18 B Unit Wiring Diagrams 19 DOCUMENT SYMBOLS Indicates additional information that is NOT related to physical injury Indicates step by step instructions INT...

Page 3: ... all safety information and instructions to avoid possible injury or death Read and understand these instructions be fore installing using servicing performing maintenance on this product Incorrect installation operation servicing maintaining of this product can lead to seri ous injury Follow all instructions The installation MUST comply with all ap plicable local or national codes including the l...

Page 4: ...n actual applications When sizing the generator the total power usage of your RV must be considered Keep in mind generators lose power at high altitudes and from lack of maintenance CIRCUIT PROTECTION Time Delay Fuse or Circuit Breaker Required B Roof Requirements A 14 1 4 x 14 1 4 1 8 square opening hereinafter referred to as roof opening is required for installing this unit This opening is part ...

Page 5: ...to product and or RV could occur The roof must be designed to support 130 pounds when RV is in motion Normally a 200 lb static load design will meet this requirement B Roof Preparation 1 FIRE OR ELECTRICAL SHOCK HAZARD Make sure there are no obstacles wires pipes etc inside RV s roof floor walls Shut OFF gas supply disconnect 120 Vac power from RV and disconnect positive 12 Vdc terminal from suppl...

Page 6: ...cts and their joints must be sealed to prevent condensation from forming on adjacent surfaces during operation of the unit 4 Return air openings must have 40 square inches minimum free area including the filter 5 Return air to the unit must be filtered to prevent dirt accumulation on unit cooling surface Frame Duct Duct Frame Frame Roof Opening Roof Opening Roof SIDE VIEW TOWARD BACK OF RV Duct Ce...

Page 7: ...7 INSTALLATION INSTRUCTIONS Return Supply Supply Return FIG 4 Return Supply Return Supply FIG 5 Return Return Supply Supply Supply Supply FIG 6 ...

Page 8: ...ning b Make sure that at least 15 of supply wire extends into the roof opening 3 Thermostat Communication Cable a CCC 2 Thermostat I Route a 4 conductor communication ca ble from the roof opening to the thermo stat mounting location using the shortest most direct route Make sure that at least 15 of the wire extends into the roof open ing and 6 extends from the wall at the thermostat mounting locat...

Page 9: ...stem load shed feature is to be used with the control two wires must be routed to the roof opening of the zone to be managed The signal required for this function is normally an open relay contact When the EMS calls for the compressor to shut off the relay contacts should close Make sure that at least 15 of the EMS wire extends into the roof opening 7 CCC 2 system only If an Automatic Generator St...

Page 10: ... Align the thermostat with the back plate and snap into position FIG 12 4 Conductor Communication Cable 2 LCD SZ System Wire colors listed for the communication cable 3 conductor cable match the wire colors in the unit wire harness and the wire harness at the LCD SZ electronic control box Available wire colors may vary a Remove the cover from the LCD SZ thermo stat Depress tab on bottom of thermos...

Page 11: ...to the side of the roof opening to access wiring H CCC 2 System Only Configuration 1 Electronic Control Configuration Depending on the equipment options installed by the RV manufacturer the appropriate dip switches will need to be switched to the ON position Placing the switch in the ON position selects that option See FIG 16 FIG 17 FIG 18 FIG 16 Dip Switches Dip switches are in the OFF position w...

Page 12: ...position h Gen Start selection Leave in the OFF position i Install unit electrical box cover and out side plastic shroud j Repeat this procedure for each additional zone FIG 18 On Position Off Position I 120 Vac Power Supply Connection 1 ELECTRICAL SHOCK HAZARD Make sure 120 Vac power is disconnected from RV Failure to obey this warning could result in death or serious injury 2 ELECTRICAL SHOCK HA...

Page 13: ...ill be necessary Wires must not extend beyond the locators See FIG 26 FIG 26 Housing Assembly Hinge Slots Strain Relief Cover Wires Trimmed And Correctly Located In Locator Stops Hinge Posts 9 While holding the strain relief cover position the housing s hinge posts into the hinge slots and press down until both lock into place See FIG 26 10 Close the strain relief cover and housing by hand Squeeze...

Page 14: ...nal 5 Connect the orange wire protruding from the roof opening to the wire of the three wire cable that goes to the thermostat COMMS terminal K CCC 2 System Low Voltage Wire Connections Make sure the positive 12 Vdc terminal is disconnected from supply battery Oth erwise damage to unit could occur 1 Connect the previously run 12 Vdc supply wires to the red and black wires protruding from the roof ...

Page 15: ...pth gauge Do NOT drill without depth gauge to en sure bit does NOT penetrate cold air duct 7 Match 3 lag with bonded sealing washer 8 Drive screw using 9 16 socket Finish installa tion with socket until base pan is lightly seated on Dometic cubes See FIG 30 Tighten mounting bolts to achieve proper foam block compression Overtightening could damage unit s base pan Under tighten ing will allow an in...

Page 16: ...s do not work disconnect the 120 Vac and 12 Vdc power supplies and verify that all wiring is correct N CCC 2 System Only Reset Checkout 1 System Reset After setting the dip switches in the electronic control do a system reset a Re connect the 12 Vdc and 120 Vac power supplies b Make sure the CCC 2 thermostat is in the OFF mode c Simultaneously press the MODE and ZONE buttons The LCD will display I...

Page 17: ...rning and giving it a head start on the expected high outdoor ambient will greatly improve its ability to maintain the desired indoor temperature For a more permanent solution to high heat gain acces sories like Dometic outdoor patio and window awnings will reduce heat gain by removing the direct sun They also add a nice area to enjoy company during the cool of the evening B Condensation The manuf...

Page 18: ...18 A Simple RV Wiring Diagram OPTIONAL 12 VDC INPUT 2 WIRES 12 VDC INPUT 2 WIRES FIG 35 WIRING DIAGRAMS ...

Page 19: ...ASSED DIELECTRIC REVERSING VALVE BR WHT WHT BR START CAP RED WHT BLK BLU FIG 39 B Unit Wiring Diagrams 1 H541815A H541816A Wiring Diagram P2 1 3 2 4 5 6 P1 RELAY T1 NO YEL P3 P4 P5 T6 T7 BLU P6 YEL BLU RED BLK T4 RELAY NO K2 COM BLK K1 T5 T3 RED WHT COMPRESSOR DIELECTRIC USE COPPER 60 Hz 1ɸ 115 VAC CONDUCTORS ONLY 3312441 045 TO T STAT RJ 11 CABLE SENSOR FREEZE YEL BLK FACTORY WIRING FIELD WIRING ...

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