Compressors can be:
- Constant flow on off type (not recommended). Generally not available for modern high efficiency systems.
- Constant flow on off type, with multiple compressors to achieve stepped load (not recommended). Generally not available for modern high efficiency systems.
- Hot gas by pass resulting in the refrigerant mass flow circulating with the system being reduced and thus the cooling capacity reduced (not recommended). Generally not available for modern high efficiency systems. Hot gas by-pass however still utilised for freeze protection in cold weather.
- Variable speed: Inverter controlled. Utilises an external variable frequency drive – to control the speed of the compressor. The refrigerant flow rate is changed by the change in the speed of compressor. The turndown ratio depends on the system configuration and manufacturer. It modulates from c. 25% up to 100% at full capacity.
|SYSTEM||Compressor Type||Compressor Control||Refrigerant volume control||Refrigerant Type|
|Simple Split (1 to 1)||Scroll||Variable Speed.||Yes.||R410a|
|Split (1 to multiple)||Scroll||Variable Speed.||Yes.||R410a|
|Medium VRF ( 1 to 1)||Scroll||Variable Speed.||Yes.||R410a|
|VRF 1 to multi (heat recovery)||Scroll||Variable Speed.||Yes.||R410a|
|Hybrid 1 (water to rooms)||Scroll||Variable Speed.||Yes.||R410a from CU to HBC (Box). CW & HW from Box to FCUs.|
|Hybrid 2 (refrigerant to rooms)||Scroll||Variable Speed.||Yes.||R410a Refrigerant from Box to FCUs. CW from tower to HBC (Box).|