Oil return in VRF systems

[semb]

Are there special piping requirements for VFR systems to ensure oil return? (I'm thinking of upgrading my split system to VRF). I read somewhere that IQDrive ramps the compressor up to full speed for 4 mins every half hour to ensure proper oil return. How do other systems handle it?

[semb]

A little more info - in my case the compressor/condenser are roof mounted, the air handler is about 20ft below.

[nike123]

Are there special piping requirements for VFR systems to ensure oil return? (I'm thinking of upgrading my split system to VRF). I read somewhere that IQDrive ramps the compressor up to full speed for 4 mins every half hour to ensure proper oil return. How do other systems handle it?

Same!
Are you sure that you need VRF system? It is "litle" expensive for single home.

[semb]

I'm thinking about modifying my current system by adding an inverter drive and an EEV - so I'm trying to learn all I can about what the issues are. At lower loads the refrigerant flow will be lower, so I'm concerned about oil return.

[nike123]

I'm thinking about modifying my current system by adding an inverter drive and an EEV - so I'm trying to learn all I can about what the issues are. At lower loads the refrigerant flow will be lower, so I'm concerned about oil return.

That is not VRF. That is only simple inverter driven compressor system.

[soleowner]

You really can't make a true VRF system without having all the software, hardware, and components in sync.

Regarding the oil return, Daikin losses more oil into the system than Mitsubishi.

[Custom Coils]

I think you should not modify your system to VRF system.. It will cost very high..