The air-source heat pumps were tested at -22°F (-30°C) degrees below zero for the first time. All three pumps worked normally in the coldest conditions. Cooper&Hunter: Refrigerant schematics
1. The compressor.
2. The expansion valve.
3. The four-way valve.
4.Indoor unit compartment, which acts as a condenser in the heating mode.
5. Outdoor unit sensor, which operates as an evaporator in the heating mode.
6. The intercooler.
7. The control valve (Flash vaporizer). The refrigerant rotation direction in the heating mode is denoted by red arrows in the figure.
Different compressor types
» In a rotary compressor equipped with a normal lamella each piston rotates in a circular cylinder and a spring-loaded pressure lamella separates the pump outlets from each other. There can be several lamellas in the compressor. The picture shows two different operations of the same compressor.
» Swing compressor developed by Daikin is a variant of a rotation compressor operating on a lamella. The lamella is holding the stick in the piston rod. The picture shows two dif ferent operations of the same compressor.
» A two-stage compressor has two pumping units connected into a series, in which the latter usually has smaller volume. In practice, the compressor units are often stacked and operate on the same axis, but the picture shows the units in parallel for clarity.
The measurement environment
| Manufacturer | Cooper&Hunter | Daikin | Panasonic |
|---|---|---|---|
| Indoor unit | CH-12FTXHV-B | FTXZ35NV1B | CS-VZ9SKE |
| Outdoor unit | CH-12FTXHV-B | RXZ35NV1B | CU-VZ9SKE |
| Dimensions, weight | |||
| Indoor unit (WxHxD) mm | 860x305x170 | 798x295x372 | 890x295x375 |
| Weight (kg) | 11,5 | 15,0 | 14,5 |
| Outdoor unit (WxHxD) mm | 899x596x378 | 795x693x300 | 799x630x299 |
| Weight (kg) | 44,5 | 50,0 | 41,5 |
| Refrigerant / weight (kg) | R410/1,30 | R32/1,34 | R32/1,20 |
| Compressor | rotary | swing | rotary |
| Power | |||
| Heating capacity (kW) | 3,4 | 4,5 | 3,6 |
| Energy efficiency class (heating) | A+++*) | A+++*) | A+++*) |
| COP | 4,93 | ei ilm. | 5,63 |
| SCOP | 5,1*) | 5,73*) | 6,2*) |
| Noise | C&H | Daikin | Panasonic |
|---|---|---|---|
| dB(A) | 46,1 | 53,0 | 50,9 |
The measurements were used to study the air-source heat pumps’ heating power and energy consumption at different outside temperatures when heating the indoor space to 68°F (+20°C).
The magazine has chosen leaders in air flow heat pumps manufacturing, and all equipment has shown a good result in testing and proven the ability to operate at -22°F (-30°C). Cooper&Hunter’s heat pump is a pioneer in the introduction of the air-source heat pump compressor technology. The device of 12-series has a nominal heating capacity of 3.4 KW. It’s equipped with a two-stage compressor that worked during the tests. C&H distinctive feature is radio remote control and also ability to control the device using the WiFi technology. The device worked very consistently and seamlessly at very cold temperatures, with extra low noise level.
C&H heat pump with 2-stage compressor worked very stable from 44.6°F(+7°С) to 19.4°F(-7°С ), but the best results were achieved at 14°F(-10°С) (the most effective operation). Editor’s Choice: CH-12FTXHV-B – the best heat pump in terms of price / quality.