Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Air-Cooled Condensing Units
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## Each condensing unit shall be selected to match the cooling capacity and refrigerant circuiting of the DX coil or system it serves at the project design conditions.
−## Published AHRI ratings are established at 95°F outdoor dry-bulb and 45°F saturated suction temperature at sea level. Actual delivered capacity falls below the published value at higher altitude and higher outdoor design dry-bulb temperature, so the selection must be derated for the project site rather than read directly from the nameplate tons. {note}
−
−## The condensing unit capacity shall be derated for site altitude and outdoor design dry-bulb temperature in accordance with the manufacturer's correction tables.
−
−## A rooftop in a hot or high-altitude location (for example Phoenix or Denver) can lose 5% to 15% of nameplate capacity; specifying nominal tons without this correction is a common cause of undersized systems. {note}
−
```datasheet
label: Nominal Cooling Capacity
…6 unchanged lines
```
+## Published AHRI ratings are established at 95°F outdoor dry-bulb and 45°F saturated suction temperature at sea level. Actual delivered capacity falls below the published value at higher altitude and higher outdoor design dry-bulb temperature, so the selection must be derated for the project site rather than read directly from the nameplate tons. {note}
+
+## The condensing unit capacity shall be derated for site altitude and outdoor design dry-bulb temperature in accordance with the manufacturer's correction tables.
+
```datasheet
label: Rated Cooling Capacity (at design conditions)
…7 unchanged lines
```
+## A rooftop in a hot or high-altitude location (for example Phoenix or Denver) can lose 5% to 15% of nameplate capacity; specifying nominal tons without this correction is a common cause of undersized systems. {note}
+
## The condensing unit shall meet or exceed the minimum full-load EER required by ASHRAE 90.1 Table 6.8.1 for its capacity range and refrigerant type, as adopted by the local code.
−## Representative ASHRAE 90.1-2022 minimum EER values are 11.2 for units below 65,000 Btu/h, 11.0 for 65,000 to 134,999 Btu/h, 10.6 for 135,000 to 239,999 Btu/h, and 9.5 for 240,000 Btu/h and above; the adopted local code year governs the actual threshold and must be confirmed for the project. {note}
−
−## The condensing unit shall meet or exceed the minimum part-load IEER required by ASHRAE 90.1 and by DOE federal standards (10 CFR 431) for its capacity range.
−
−## Representative DOE minimum IEER values are 12.9 for units 65,000 to 134,999 Btu/h and 12.4 for 135,000 to 239,999 Btu/h, per the rule effective January 2023. A unit can satisfy the full-load EER minimum yet fail the part-load IEER threshold, so both must be checked; verify the effective DOE rule edition for the procurement year. {note}
−
```datasheet
label: Minimum Full-Load Efficiency (EER)
…6 unchanged lines
```
+## Representative ASHRAE 90.1-2022 minimum EER values are 11.2 for units below 65,000 Btu/h, 11.0 for 65,000 to 134,999 Btu/h, 10.6 for 135,000 to 239,999 Btu/h, and 9.5 for 240,000 Btu/h and above; the adopted local code year governs the actual threshold and must be confirmed for the project. {note}
+
+## The condensing unit shall meet or exceed the minimum part-load IEER required by ASHRAE 90.1 and by DOE federal standards (10 CFR 431) for its capacity range.
+
```datasheet
label: Minimum Part-Load Efficiency (IEER)
…6 unchanged lines
```
+## Representative DOE minimum IEER values are 12.9 for units 65,000 to 134,999 Btu/h and 12.4 for 135,000 to 239,999 Btu/h, per the rule effective January 2023. A unit can satisfy the full-load EER minimum yet fail the part-load IEER threshold, so both must be checked; verify the effective DOE rule edition for the procurement year. {note}
+
+## The efficiency tier of the condensing unit shall be specified, and the selected unit shall meet or exceed both the full-load EER and part-load IEER minimums for its capacity range.
+
```datasheet
label: Efficiency Tier
…9 unchanged lines
## The refrigerant type shall be specified explicitly and shall match the refrigerant of the evaporator section served.
−## The transition from R-410A (an A1 refrigerant) to A2L refrigerants such as R-454B and R-32 is actively underway under the AIM Act, and manufacturers are discontinuing R-410A equipment on a model-by-model basis. New construction should not assume R-410A availability; the specified refrigerant must be procurable for the anticipated equipment order date, and the condensing unit and evaporator must share the same refrigerant. {note}
−
−## R-22 shall be specified only for like-for-like replacement of existing equipment, never for new installations.
−
−## The refrigerant safety classification shall be confirmed against ASHRAE 34, and A2L systems shall comply with the charge limits, ventilation, and mitigation requirements triggered by that classification.
−
−## ASHRAE 34 assigns the safety group (A1, A2L, A2, B2L, and so on) that determines maximum charge per occupied space, ventilation requirements, and whether leak detection and mitigation are mandatory. ASHRAE 15 Table 1 establishes the maximum refrigerant charge for the smallest occupied space served. {note}
−
```datasheet
label: Refrigerant
…7 unchanged lines
```
+## The transition from R-410A (an A1 refrigerant) to A2L refrigerants such as R-454B and R-32 is actively underway under the AIM Act, and manufacturers are discontinuing R-410A equipment on a model-by-model basis. New construction should not assume R-410A availability; the specified refrigerant must be procurable for the anticipated equipment order date, and the condensing unit and evaporator must share the same refrigerant. {note}
+
+## R-22 shall be specified only for like-for-like replacement of existing equipment, never for new installations.
+
+## The refrigerant safety classification shall be confirmed against ASHRAE 34, and A2L systems shall comply with the charge limits, ventilation, and mitigation requirements triggered by that classification.
+
```datasheet
label: Refrigerant Safety Group (ASHRAE 34)
…5 unchanged lines
```
+## ASHRAE 34 assigns the safety group (A1, A2L, A2, B2L, and so on) that determines maximum charge per occupied space, ventilation requirements, and whether leak detection and mitigation are mandatory. ASHRAE 15 Table 1 establishes the maximum refrigerant charge for the smallest occupied space served. {note}
+
## The factory refrigerant charge shall be as listed on the unit nameplate, and field charge shall be added per the manufacturer's table for line-set length beyond the rated default.
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## The number of refrigerant circuits shall be selected for the redundancy and staging needs of the application.
−## Single-circuit units are simpler and suit smaller or non-critical loads. Dual-circuit units provide capacity redundancy and staging flexibility and are recommended for critical, 24/7, or process facilities such as server rooms, where loss of a single circuit must not take the whole system offline. {note}
−
```datasheet
label: Number of Refrigerant Circuits
…5 unchanged lines
```
+## Single-circuit units are simpler and suit smaller or non-critical loads. Dual-circuit units provide capacity redundancy and staging flexibility and are recommended for critical, 24/7, or process facilities such as server rooms, where loss of a single circuit must not take the whole system offline. {note}
+
## The compressor staging and capacity control shall be selected to match the load profile of the system served.
−## Options range from on/off single-stage through two-stage compressors, variable-speed condenser fans, and inverter-driven compressors. Variable-speed and inverter control improve part-load efficiency and capacity matching but cost more; the IEER requirement and the load profile drive the choice. {note}
−
```datasheet
label: Capacity Control / Staging
…7 unchanged lines
```
+## Options range from on/off single-stage through two-stage compressors, variable-speed condenser fans, and inverter-driven compressors. Variable-speed and inverter control improve part-load efficiency and capacity matching but cost more; the IEER requirement and the load profile drive the choice. {note}
+
## Each compressor shall be mounted on integral vibration isolators within the cabinet.
…127 unchanged lines
## Vibration isolation shall be selected for the structural sensitivity of the supporting structure.
−## Integral rubber isolators are standard and adequate for most slab and grade installations. Spring isolators are used where the supporting structure is sensitive to transmitted vibration, such as lightweight roof framing over occupied spaces. {note}
−
```datasheet
label: Vibration Isolation
…5 unchanged lines
```
+## Integral rubber isolators are standard and adequate for most slab and grade installations. Spring isolators are used where the supporting structure is sensitive to transmitted vibration, such as lightweight roof framing over occupied spaces. {note}
+
## In Seismic Design Category C and above, seismic restraint complying with ASCE 7 shall be provided.
…36 unchanged lines
## Refrigerant piping between the condensing unit and the evaporator section shall be designed and installed per [[sync/refrigerant-piping]], including maximum line-set length, oil-trap locations, and field charge-add quantities.
−## These quantities are not part of the condensing-unit section and must be explicitly delegated to the piping standard; the design also must confirm maximum equivalent line-set length (commonly up to 150 to 200 ft with oil traps) and maximum equivalent height difference (commonly 50 ft without special piping) for the selected unit. {note}
+## These quantities are not part of the condensing-unit section and must be explicitly delegated to the piping standard; the design also must confirm maximum equivalent line-set length (commonly up to 150 to 200 ft with oil traps) and maximum equivalent height difference (commonly 50 ft without special piping) for the selected unit.
## The condensing unit shall be installed on a pad, curb, or wall bracket suitable for the unit weight and the mounting method shown.
…50 unchanged lines
- One spare set of contactors / control relays
```