This article provides a detailed review of the installation instructions for Aspen evaporator coils, focusing on technical specifications, safety precautions, and best practices for qualified technicians. The information is drawn exclusively from the official installation instructions provided by Aspen for HVAC equipment. The goal is to present a clear, accurate, and actionable reference for professionals involved in HVAC installation and maintenance.
Introduction
Aspen evaporator coils are integral components in HVAC systems, and their proper installation is critical for system performance, safety, and warranty compliance. The installation process involves adherence to specific technical guidelines, including refrigerant line sizing, drain pan configuration, and the use of appropriate expansion devices such as thermostatic expansion valves (TXVs) or flowrator devices.
The installation instructions emphasize the importance of using qualified personnel, following local and national building codes, and ensuring that all components are installed in a manner that prevents damage, health risks, and voiding of warranties. This article compels a step-by-step breakdown of the key considerations and procedures for installing Aspen evaporator coils, with a focus on best practices and technical accuracy.
General Installation Considerations
Qualified Personnel and Legal Requirements
Aspen’s installation instructions explicitly state that the work must be carried out by qualified individuals who are trained and experienced in HVAC equipment installation. In some jurisdictions, installation personnel are required to be licensed, and unqualified individuals must not attempt the installation or interpret the instructions.
This requirement is not merely a legal formality but a safety measure. Improper installation can lead to system inefficiencies, equipment damage, and potential exposure to refrigerants such as chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which may pose health risks under certain conditions. Any suspected leak should be addressed immediately by a licensed service technician.
Compliance with Codes and Warranty Implications
The instructions also make it clear that the product is designed to meet local and national building codes. It is the installer’s responsibility to ensure that the installation complies with these codes. Failure to do so not only risks system performance but can also void the product warranty.
Installation Precautions
Secondary Drain Pan Requirements
A key aspect of the installation involves managing condensate to prevent water damage. The instructions distinguish between coil models and installation scenarios:
CQ Series Coils: These have a secondary drain pan factory installed within the cabinet. A field-installed secondary drain pan is not required for these models. However, the drain line must still be installed according to the instructions provided.
General Horizontal Coils: When installed in locations where damage from condensate overflow is a risk (e.g., above ceilings), a secondary drain pan must be installed by the technician. This pan must be placed under the entire unit and connected to a separate, properly sloped drain line that terminates in a visible location. The secondary drain pan serves as an additional layer of protection in case the primary drain becomes clogged.
Red Drain Plugs: These should not be reused without the use of plumber's tape or putty to ensure a secure and leak-free connection.
Attic Installations: In attic spaces where the coil is placed on the floor, the use of an isolation pad is recommended to reduce sound transmission to the ceiling below.
Refrigerant Line and Brazing Guidelines
Proper handling of refrigerant lines is essential to ensure system integrity and safety:
Refrigerant Line Sizing: The instructions advise using the refrigerant line sizes recommended by the outdoor unit manufacturer. This ensures optimal flow and prevents performance issues or equipment damage.
Schrader Valve Protection: Some Aspen coils may include a Schrader valve on the suction manifold. This valve must be protected from heat during installation to prevent leakage. Any exposure to high temperatures should be avoided.
Brazing Best Practices: Refrigerant connections should be brazed using appropriate techniques. If grommets are present, they should be removed prior to brazing and reinstalled after the lines have cooled. This prevents damage to the grommets during the heating process.
TXV Valve Installation: For thermostatic expansion valve (TXV) coils, several key steps are outlined:
- Sensing Bulb Placement: The sensing bulb must be placed in direct contact with the suction line, on a horizontal plane, and at either the 4 or 8 o'clock position. It must also be insulated from external air to avoid false readings.
- Protection During Brazing: Both the sensing bulb and the TXV body must be protected during brazing by either removing the bulb or covering it with a wet cloth. The flame should be directed away from the valve body to prevent overheating.
Valve Selection and Sizing: The TXV must be selected based on the refrigerant type (R22 or R410a) and the capacity of the outdoor unit. TXV caps are color-coded—green for R22 and pink for R410a—to aid in identification. The valve should be sized according to the outdoor unit’s capacity to avoid system inefficiencies or compressor damage.
Flowrator Coils: Piston Sizing and Application
Flowrator coils are designed for both heat pump and cooling-only applications. The piston size is critical for system performance and must be selected based on the outdoor unit's capacity. If the manufacturer’s recommendation is unavailable, a sizing chart is provided to assist the installer in selecting the appropriate piston.
| Outdoor Unit Capacity | R22 Orifice Size | R410a Orifice Size |
|---|---|---|
| 12,000 | 0.041 | N/A |
| 18,000 | 0.055 | 0.049 |
| 24,000 | 0.059 | 0.055 |
| 30,000 | 0.068 | 0.059 |
| 36,000 | 0.074 | 0.068 |
| 42,000 | 0.080 | 0.074 |
| 48,000 | 0.084 | 0.080 |
| 60,000 | 0.092 | 0.089 |
The factory-installed piston size is stamped on the piston body. If the outdoor unit has a different nominal capacity than the coil, the piston must be replaced to match the new capacity. The use of an incorrect piston can lead to poor system performance and potential compressor failure.
TXV and Expansion Valve Coils
For coils equipped with thermostatic expansion valves (TXVs) or non-bleed expansion valves (X2, X4, X5, X, 4), additional considerations are outlined:
Hard-Start Kits: Some models may require the use of hard-start kits. The installer is advised to follow the guidelines provided by the outdoor unit manufacturer.
Time Delay Relays: If a time delay relay is used, it should be adjusted to the optimum delay recommended by the outdoor unit manufacturer. This helps prevent electrical surges and ensures smooth system operation.
TXV Equalizer Tube Installation: A 1/4" hole must be punched into the suction line manifold using a pick or similar tool. The TXV equalizer tube should then be inserted approximately 3/8" into the hole and soldered to form a secure seal. Drilling is discouraged as it can introduce metal chips into the manifold.
System Charging and Performance Optimization
After installation, system charging is a critical step in ensuring optimal performance:
Airflow and Static Pressure: Airflow should be increased to the maximum CFM possible without exceeding a 0.3 in. wet coil static pressure drop across the coil. This helps maintain efficient heat exchange without overloading the system.
Flowrator Coils: For these coils, refrigerant should be added until the superheat measured at the outdoor unit suction line matches the values in the following chart:
| Outdoor Temp °F D.B. | Superheat °F (Min) | Superheat °F (Nom) | Superheat °F (Max) |
|---|---|---|---|
| 65 | 35 | 40 | 45 |
| 70 | 31 | 35 | 39 |
| 75 | 26 | 30 | 34 |
| 80 | 22 | 25 | 28 |
| 85 | 17 | 20 | 23 |
| 90 | 13 | 15 | 17 |
- Expansion Valve Coils: For these systems, refrigerant should be added until the subcooling measured at the outdoor unit liquid line matches the manufacturer's recommended temperature (typically between 7°–10°F). If no specific value is provided, the chart above can be used as a reference.
Additional Installation Tips
Cabinet Sealing and Insulation: The coil cabinet should be taped to ensure an airtight seal, and the suction line must be insulated to prevent heat loss and condensation.
Downflow Coils: These should not exceed 350 CFM/ton to maintain system efficiency and prevent excessive pressure drops.
Labeling and Identification: A valve identification sticker should be placed adjacent to the Aspen model number on the unit nameplate. This helps with future service and maintenance.
Drain Line Installation: Drain lines from an auxiliary pan must be installed but should not be connected to the primary drain line of the coil. This ensures that any overflow from the primary drain is captured by the secondary pan without overloading the primary system.
Conclusion
Aspen evaporator coil installation is a complex and technically demanding process that requires adherence to strict guidelines, safety precautions, and performance specifications. The instructions emphasize the importance of using qualified personnel, following local building codes, and ensuring that all components are properly sized and installed to avoid system inefficiencies, equipment damage, and warranty voidance.
Key considerations include the use of secondary drain pans, proper refrigerant line sizing, accurate TXV and piston selection, and adherence to airflow and pressure specifications during system charging. The documentation provides detailed charts and step-by-step instructions that are essential for ensuring a successful installation.
By following these guidelines, HVAC professionals can ensure that Aspen evaporator coils are installed in a manner that optimizes system performance, safety, and longevity.