Copper Tube (Apply heat for 10-15 seconds)

Bi-metallic Tube Connection (Apply heat for 2-5 seconds)

Braze Rod

(’Sil-Phos” = 5.5% Silver, 6% Phosphorus)

Use of a wet cloth is not neces- sary due to rapid heat dissipation of the bi--metallic connections

Figure 6-12 Hermetic Thermostatic Expansion Valve Brazing Procedure

 

7. If applicable, braze the equalizer connection to the

 

equalizer line.

 

8. Check superheat (refer to step 6.14.1).

INLET

6.15 EVAPORATOR COIL AND HEATER

 

ASSEMBLY

 

The evaporator section, including the coil, should be

 

cleaned regularly. The preferred cleaning fluid is fresh

 

water or steam. Another recommended cleaner is Oakite

OUTLET

202 or similar, following manufacturer’s instructions.

The two drain pan hoses are routed behind the

 

 

condenser fan motor and compressor. The drain pan

 

Figure 6-13 Economizer Expansion Valve

line(s) must be open to ensure adequate drainage.

6.15.1 Evaporator Coil Replacement

1. Pump down the unit per paragraph 6.4.

a. Pump unit down. (Refer to paragraph 6.4.)

 

2.Remove cushion clamps located on the inlet and out- let lines.

3.Unbraze the equalizer connection (if applicable), the outlet connection and then the inlet connection.

4.Remove insulation (Presstite) from expansion valve bulb.

5.Unstrap the bulb, located below the center of the suc- tion line (4 o’clock position), and remove the valve.

b. Installing the Expansion Valve

1.Clean the suction line with sandpaper before instal- ling bulb to ensure proper heat transfer. Apply ther- mal grease to the indentation in the suction line.

2.Strap the thermal bulb to the suction line, making sure bulb is placed firmly into the suction line. See Figure 6-10 for bulb placement.

3.Insulate the thermal bulb.

4.The economizer expansion valves should be wrapped in a soaked cloth for brazing. See Figure 6-12. Braze inlet connection to inlet line

5.Braze outlet connection to outlet line.

6.Reinstall the cushion clamps on inlet and outlet lines.

b. With power OFF and power plug removed, remove the screws securing the panel covering the evaporator section (upper panel).

c. Disconnect the defrost heater wiring.

d. Disconnect the defrost temperature sensor (see Fig- ure Figure 2-2 from the coil. .

e. Remove middle coil support.

f.Remove the mounting hardware from the coil.

g.Unsolder the two coil connections, one at the distrib- utor and the other at the coil header.

h.After defective coil is removed from unit, remove defrost heaters and install on replacement coil.

i.Install coil assembly by reversing above steps.

j.Leak check connections per paragraph 6.5. Evacuate the unit per paragraph 6.6 and add refrigerant charge per paragraph 6.7.

6.15.2 Evaporator Heater Replacement

a.Before servicing unit, make sure the unit circuit break- ers (CB-1 & CB-2) and the start-stop switch (ST) are in the OFF position, and that the power plug and cable are disconnected.

b. Remove the lower access panel (Figure 2-1) by removing the T.I.R. locking device lockwire and mounting screws.

T-309

6-10

Page 73 Page 75
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Image 74
Carrier 69NT20-531-300 If applicable, braze the equalizer connection to, Equalizer line, Check superheat refer to step
Page 73 Page 75

69NT20-531-300 specifications

The Carrier 69NT20-531-300 is a cutting-edge rooftop unit designed to meet the demanding requirements of commercial heating and cooling applications. This model embodies Carrier’s commitment to energy efficiency, reliability, and advanced technological features that enhance indoor comfort while minimizing operational costs.

One of the standout features of the Carrier 69NT20-531-300 is its high energy efficiency. It is equipped with advanced compressor technology that optimizes performance while reducing energy consumption. This ensures that businesses can maintain a comfortable indoor climate without incurring exorbitant utility bills. With a high Seasonal Energy Efficiency Ratio (SEER) and Energy Efficiency Ratio (EER), users can expect not only enhanced comfort but also significant cost savings over time.

The cooling capabilities of the 69NT20-531-300 are complemented by its robust heating options. This unit utilizes a gas heat exchanger, ensuring quick and even heating throughout the space. The combination of cooling and heating capabilities in one compact unit makes it a versatile choice for various applications, including retail spaces, offices, and warehouses.

In addition to its impressive performance specifications, the Carrier 69NT20-531-300 incorporates innovative technologies that further enhance its functionality. The unit comes with advanced controls, allowing for precise temperature regulation and zoning capabilities. This ensures that different areas of a building can maintain their desired temperatures based on usage, improving overall energy efficiency.

Durability is another hallmark of the Carrier 69NT20-531-300. The unit is constructed with high-quality materials and features a weather-proof cabinet that protects it from the elements, ensuring long-term reliability even in harsh conditions. Furthermore, its modular design simplifies maintenance, making it easy for technicians to access critical components.

The 69NT20-531-300 is also designed with low noise operation in mind. It employs sound-dampening technology to ensure that operations are quiet, making it an ideal choice for locations where noise reduction is a priority, such as schools or healthcare facilities.

Overall, the Carrier 69NT20-531-300 stands out as a premier choice for businesses looking for an efficient, reliable, and feature-rich rooftop HVAC unit. Its blend of energy efficiency, advanced technology, and durability positions it as a leader in commercial heating and cooling solutions, making it a valuable investment for any commercial property.
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