TABLE OF CONTENTS The project began with modifications to an existing 3-ton (10.6 kW) variable-speed air-to-air heat pump. The machine has an ARI 210/240 rating of SEER=15.2 (COP=4.5) and an HSPF=8.75 (COP=2.6) (ARI 1992). Table 1 lists the performance data at various conditions.
| COOLING @ 80 /67 F (27 /19 C) EAT | |||
|---|---|---|---|
| Low Speed | High Speed | ||
| Capacity @ 95 F | OAT | 12.6 MBtuh | 37.5 MBtuh |
| 35 COAT | OAT | 3.70 kW | 11.0 kW |
| EER @ 95 F OAT | 24.3 | 9.40 | |
| COP @ 35 F OAT | 7.12 | 2.75 | |
| [*] Capacities and COPs do not include defrost penalty. |
| HEATING @ 70 F (21 C) [*] | ||||
|---|---|---|---|---|
| Low Speed | High Speed | |||
| Capacity @ 47 F | OAT | 11.8 MBtuh | 34.6 MBtuh | |
| 8 C | OAT | 3.46 kW | 10.1 kW | |
| @ 17 F | OAT | 6.5 MBtuh | 19.3 MBtuh | |
| 1.9 kW | 5.7 kW | |||
| COP @ 47 F | (8 C) | 3.66 | 3.06 | |
| @ 17 F | (-8 C) | 2.24 | 1.92 | |
| [*] Capacities and COPs do not include defrost penalty. |
The heat pump was installed as recommended by the manufacturer and tested at a variety of indoor and outdoor air conditions. The unit operated between 3% and 7% below published performance.
The compressor and power electronics were removed from the outdoor coil and installed in a cabinet indoors. A nominal 48 MBtuh (14.1 kW) coaxial water-to-refrigerant coil replaced the outdoor coil, and a vented 24 MBtuh (7.0 kW) water-to-refrigerant coil was placed at the compressor discharge. These coils, the heating mode thermostatic expansion valve (TEV), and the reversing valve are also...
