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508133G01 / 31-5000715

Issue 2140

Refrigerant Piping

•  Use only refrigerant grade copper tubes. 
•  Split systems may be installed with up to 50 feet of 

line set (no more than 20 feet vertical) without special 

consideration (see long line set guidelines). 

•  Ensure that vapor and liquid tube diameters are 

appropriate to capacity of unit.

•  Run refrigerant tubes as directly as possible by 

avoiding unnecessary turns and bends.

•  When passing refrigerant tubes through the wall, seal 

opening with RTV or other silicon-based caulk.

•  Avoid direct tubing contact with water pipes, duct work, 

floor joists, wall studs, floors, walls, and any structure.

•  Do not suspend refrigerant tubing from joists and 

studs with a rigid wire or strap that comes in direct 

contact with tubing.

•  Ensure that tubing insulation is pliable and completely 

surrounds vapor tube.

It is important that no tubing be cut or seals broken until you 

are ready to actually make connections to the evaporator 

and to the condenser section. DO NOT remove rubber 

plugs or copper caps from the tube ends until ready to 

make connections at evaporator and condenser. Under no 

circumstances leave the lines open to the atmosphere for 

any period of time, if so unit requires additional evacuation 

to remove moisture.

Operating 

Mode

18 SEER

Liquid Line

Suction Line

2 Ton

3/8

3/4

3 Ton

3/8

3/4

4 Ton

3/8

7/8

5 Ton

3/8

1-1/8

Table 2.  

Be extra careful with sharp bends. Tubing can “kink” very 

easily, and if this occurs, the entire tube length will have 

to be replaced. Extra care at this time will eliminate future 

service problems.

It is recommended that vertical suction risers not be up-

sized. Proper oil return to the compressor should be 

maintained with suction gas velocity.

Filter Drier

The filter drier is very important for proper system operation 

and reliability. If the drier is shipped loose, it must be 

installed by the installer in the field. Unit warranty will be 

void, if the drier is not installed.

Installation of Line Sets

DO NOT

 fasten liquid or suction lines in direct contact with 

the floor or ceiling joist. Use an insulated or suspension 

type of hanger. Keep both lines separate, and always 

insulate the suction line. Liquid line runs (30 feet or more) 

in an attic will require insulation. Route refrigeration line 

sets to minimize length.

DO NOT

 let refrigerant lines come in direct contact with 

foundation. When running refrigerant lines through the 

foundation or wall, openings should allow for a sound 

and vibration absorbing material to be placed or installed 

between tubing and foundation. Any gap between 

foundation or wall and refrigerant lines should be filled with 

a vibration damping material.

If ANY refrigerant tubing is required to be buried by state 

or local codes, provide a 6 inch vertical rise at service 

valve. 

 CAUTION

DO LOCATE THE UNIT:

•  With proper clearances on sides and top of unit
•  On a solid, level foundation or pad (unit must be level 

to  within  ±  1/4  in./ft.  per  compressor  manufacturer 

specifications)

•  To minimize refrigerant line lengths

DO NOT LOCATE THE UNIT:

•  On brick, concrete blocks or unstable surfaces
•  Near clothes dryer exhaust vents
•  Near sleeping area or near windows
•  Under eaves where water, snow or ice can fall directly 

on the unit 

•  With clearance less than 2 ft. from a second unit
•  With clearance less than 4 ft. on top of unit

Operating Ambient

The minimum outdoor operating ambient in cooling mode 

is 55°F, and the maximum outdoor operating ambient in 

cooling mode is 125°F. The maximum outdoor operating 

ambient in heating mode is 66°F.

Rooftop Installations

Install unit at a minimum of 6” above surface of the roof 

to avoid ice buildup around the unit. Locate the unit 

above a load bearing wall or area of the roof that can 

adequately support the unit. Consult local codes for rooftop 

applications.

If unit cannot be mounted away from prevailing winds, a 

wind barrier should be constructed. Due to variation in 

installation applications, size and locate barrier according 

to the best judgment of the installer.

Summary of Contents for NS18HMA

Page 1: ...ion and service performed by unqualified persons can result in property damage personal injury or death WARNING Sharp metal edges can cause injury When installing the unit use care to avoid sharp edge...

Page 2: ...ll safety codes Wear safety glasses and work gloves Use quenching cloth for brazing operations Have fire extinguisher available Read these instructions thoroughly and follow all warning or cautions at...

Page 3: ...m building not to exceed 1 4 per foot Figure 1 Slab Mounting Install on a Solid Level Mounting Pad The outdoor section is to be installed on a solid foundation This foundation should extend a minimum...

Page 4: ...warranty will be void if the drier is not installed Installation of Line Sets DO NOT fasten liquid or suction lines in direct contact with the floor or ceiling joist Use an insulated or suspension typ...

Page 5: ...listed in Table 3 Between 51 and 150 Linear Feet Crankcase heater and nonbleed port TXV factory installed No additional components required Vertical vapor riser must be sized to the vapor riser liste...

Page 6: ...iquid line size shaded row on the outdoor tonnage C Select the actual Total Linear Length of your system shown at the top of the table D The elevation listed in the table is the maximum allowed for th...

Page 7: ...ponents including line set and indoor coil must be an AHRI match with the unit in order to fulfill unit warranty requirements Fire Explosion and Personal Safety hazard Failure to follow this warning c...

Page 8: ...around the stubbed end of the check expansion valve and lightly lubricate the connector threads and expose surface of the Teflon ring with refrigerant oil 4 Attach the stubbed end of the check expans...

Page 9: ...ain round Do not crimp end of the line Remove service cap and core from both the vapor and liquid line service ports 1 2 LIQUID LINE SERVICE VALVE SERVICE PORT CORE SERVICE PORT CAP SERVICE PORT CORE...

Page 10: ...all water saturated cloths WHEN BRAZING LINE SET TO SERVICE VALVES POINT FLAME AWAY FROM SERVICE VALVE PREPARATION FOR NEXT STEP 7 WRAP SERVICE VALVES To help protect service valve seals during brazin...

Page 11: ...sig 1034 kPa Open the valve on the high side of the manifold gauge set in order to pressurize the line set and the indoor unit E After a few minutes open one of the service valve ports and verify that...

Page 12: ...r liquid refrigerant Open the manifold gauge valve 1 to 2 psig in order to release the vacuum in the line set and indoor unit G Perform the following Close manifold gauge valves Shut off HFC 410A cyli...

Page 13: ...1 is jumpered to Y2 in the outdoor unit Note that the published performance data is based upon the use of a two stage thermostat Refer to the NS18HMA field wiring diagram for a conventional 24VAC sing...

Page 14: ...hermostat Control Options Size Circuit and Install Service Disconnect Switch Refer to the unit nameplate for minimum circuit ampacity and maximum fuse or circuit breaker HACR per NEC Install power wir...

Page 15: ...100 30m 18 Temperature Rating 35 C Minimum More than 100 30m 16 Table 7 Conventional 24VAC Thermostat Wiring Route High Voltage and Ground Wires Any excess high voltage field wiring should be trimmed...

Page 16: ...RMOSTAT W L Y2 Y1 O DS C I I R DF TST Y1 O C W1 R G TC TO ACC2 ACC1 Y1 O DH C W2 W1 R G DS W2 FOR SINGLE STAGE OPERATION INSTALL A JUMPER BETWEEN Y1 TO Y2 ON THE OUTDOOR UNIT TERMINAL STRIP Figure 9 C...

Page 17: ...If the intended capacity for the application is 3 or 5 Ton skip this section The units are field convertible to 2 Ton or 4 Ton to efficiently perform for the required application If the intended capa...

Page 18: ...itiate the Charge Mode A heating blower demand must also be provided to initiate high speed blower operation on the indoor unit The compressor and outdoor fan motor will begin to ramp up and reach 100...

Page 19: ...ooling indoor blower operation In single stage thermostat applications a jumper must be installed between Y1 and Y2 on the NS18HMA outdoor control The compressor will be controlled in the variable cap...

Page 20: ...late to list the actual field charge Table 11 Refrigerant Charge Adjustment Liquid Line Set Diameter Oz Per 5 ft adjust from 15 ft line set 3 8 in 3 oz per 5 ft or 0 6 oz per 1 ft If line length is gr...

Page 21: ...testing is completed replace service port cap Tighten finger tight then an additional 1 6 turn To Open Liquid or Suction Line Service Valve 1 Remove stem cap with an adjustable wrench 2 Use service wr...

Page 22: ...in mild detergent and rinsing with cold water Allow filter to dry before reinstalling Replace filters with the arrows pointing in the direction of airflow Dirty filters are the most common cause of p...

Page 23: ...heat pump to automatically switch from heating mode to cooling mode to maintain predetermined comfort settings Many heat pump thermostats are also equipped with an emergency heat mode which locks out...

Page 24: ...Page 24 of 25 508133G01 31 5000715 Issue 2140 Figure 15 Wiring Diagram...

Page 25: ...____________ Actual Amps ______ Rated Volts _______ Actual Volts ________ Condenser Fan Full Load Amps _________ Actual Amps ______ Cooling Mode Suction Pressure ____________________ Liquid Pressure _...

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