Haier Air Conditioner Repair Q&A; Differences and Advantages of Inverter Air Conditioners vs. Fixed-Speed Air Conditioners
1. The cooling capacity of fixed-speed air conditioners decreases as the outdoor temperature rises, while the room's thermal load increases with rising outdoor temperatures. This leads to insufficient cooling in fixed-speed air conditioners. Inverter air conditioners can adjust the speed of the compressor motor based on changes in the room's thermal load, achieving rapid cooling or heating with minimal temperature fluctuations. For example, when the room requires a quick drop or rise in temperature, the inverter outputs high-frequency alternating current (AC), increasing the speed of the compressor motor and thus increasing its cooling or heating capacity. When the required cooling or heating capacity is low, the inverter outputs low-frequency AC, reducing the speed of the compressor motor and decreasing its cooling or heating capacity accordingly. This achieves automatic matching of cooling capacity with the room's thermal load and saves energy.
2. Fixed-speed air conditioners start and operate at a fixed frequency, with starting currents greater than their rated current. Inverter air conditioners have very low starting currents for their compressors and do not experience frequent starts, operating mostly at low speeds. Thus, they produce less noise, cause less mechanical wear, and have longer lifespans. Over long-term operation, inverter air conditioners are more energy-efficient than fixed-speed ones.
3. Fixed-speed air conditioners cannot start their compressors if the voltage drops below 180V. The motors in inverter air conditioners are powered by inverters, which are not directly linked to mains voltage. Therefore, these air conditioners have fewer voltage requirements and can run stably even when there are significant fluctuations in power supply voltage. Inverter air conditioners can start at reduced frequencies even at very low voltages, with a minimum starting voltage of 150V.
4. Fixed-speed air conditioners use simple temperature regulation methods, leading to large temperature fluctuations, with a maximum range of up to 2°C. When the indoor temperature reaches the set point, the compressor stops working; when the indoor temperature rises by 1°C above the set point, the compressor restarts. Inverter air conditioners provide precise temperature regulation with fluctuations of only 1°C. For every 0.5°C decrease in room temperature, the compressor's operating frequency drops by one level; conversely, for every 0.5°C increase in room temperature, the compressor's operating frequency increases by one level. Higher room temperatures result in higher compressor frequencies for faster cooling, while closer proximity to the set temperature results in lower compressor frequencies and reduced cooling output to maintain the set temperature with minimal fluctuations.
5. In fixed-speed air conditioners, the compressor operates at the same speed for both cooling and heating modes, and system matching is used to improve the heat-to-cooling ratio, which has significant limitations. In inverter air conditioners, the compressor runs at much higher speeds during heating compared to cooling, allowing for a heat-to-cooling ratio of over 140%. During heating, the highest operating frequency is often about 20Hz higher than during cooling.
6. Fixed-speed air conditioners have constant compressor speeds, providing little heating effect below 0°C. Inverter air conditioners operate at high frequencies in low-temperature environments, producing 3 to 4 times the heating capacity of fixed-speed air conditioners. Even at -10°C outdoors, they still provide excellent heating performance.
7. Whenever fixed-speed air conditioners encounter overcurrent or overvoltage protection, the compressor must stop. Inverter air conditioners, upon circuit protection events, can reduce their operating frequency appropriately to buffer the issue, thus achieving continuous operation without affecting user experience.
8. Fixed-speed air conditioners have poor defrosting performance and create a cold sensation during dehumidification. Inverter air conditioners defrost accurately and quickly, requiring only half the time of fixed-speed models. During dehumidification, they operate at low frequencies, removing moisture without lowering the temperature.
Compiled and edited by Haier Air Conditioner After-sales Service Center Beijing, September 23, 2011.