VRF Crankcase Heat

[Husky250]

Hi All,

I visited a LG Multi-V system and questioned why the crankcase heat was not energized. It was 5.7 degrees outside and the system had been powered for one week, but had not functioned. My thinking was liquid migration would be certain even if the system had an accumalator in. The crankcase heat did energize, but not until 5.3 degrees or colder. I felt crankcase heat should have been on much sooner.

Is there a reason crankcase heat would not energize until it was so cold? Do other brands of VRF energize compressor heat this cold as well?

Had I started the unit, the Inverter compressor would have started with no crankcase heat on for one week at temperatures of 5.7 degrees. The compressors were very cold to the touch. I was very concerned.

Any thoughts?

[nike123]

Hi All,

I visited a LG Multi-V system and questioned why the crankcase heat was not energized. It was 5.7 degrees outside and the system had been powered for one week, but had not functioned. My thinking was liquid migration would be certain even if the system had an accumalator in. The crankcase heat did energize, but not until 5.3 degrees or colder. I felt crankcase heat should have been on much sooner.

Is there a reason crankcase heat would not energize until it was so cold? Do other brands of VRF energize compressor heat this cold as well?

Had I started the unit, the Inverter compressor would have started with no crankcase heat on for one week at temperatures of 5.7 degrees. The compressors were very cold to the touch. I was very concerned.

Any thoughts?

Fujitsu VRF :

2) Output control of the crank case heaters
The crank case heaters turn ON if the outdoor temperature is less than 20 C and the outdoor unit has already
stopped operating for more than 1 hour.
The crank case heaters turn OFF if the outdoor temperature becomes higher than 25 C or if the outdoor unit
started to operate.


Don't worry, that is LG (Lucky Gold Star). They know what are they doing.:o

[multisync]

Fujitsu VRF :


Don't worry, that is LG (Lucky Gold Star). They know what are they doing.:o


Your best ever post!

[Husky250]

Fujitsu VRF :


Don't worry, that is LG (Lucky Gold Star). They know what are they doing.:o

I find it really hard to believe refrigerant is not migrating in long off cycles. Crankcase heat not energized until 5.7 degrees is insane in my opinion. I am not that familiar with VRF equipment, but still cant see how liquid is not making its way to the compressor. This site has experienced numerous Inverter over amperage alarms, and I think it may be possible liquid refrigerant may be causing some of the problem. It cant be helping.

Also, the systems are way oversized for the load inside the space. One system runs constant while others experience frequent on / off times. The frequent on / off of the outdoor unit reduces lubrication of the compressor which could be accounting for some of the Inverter over amperage alarms along with no compressor heat at 5.7 degrees. Some outdoor and Indoor units simply dont run as setpoint is reached, so they sit there as the load is the same in the entire building. Again, no compressor heat.

I was almost ready to fit compressor crankcase heat with a T-Stat. Energized anytime outdoor temperature is below 20 to 18 degrees. My only concern was I am afraid it may affect high compressor discharge temperatures.

Has anyone installed crankcase heat on large VRF equipment before? Would it have negative effects on the system?

Thank everyone.

[multisync]

I find it really hard to believe refrigerant is not migrating in long off cycles. Crankcase heat not energized until 5.7 degrees is insane in my opinion. I am not that familiar with VRF equipment, but still cant see how liquid is not making its way to the compressor. This site has experienced numerous Inverter over amperage alarms, and I think it may be possible liquid refrigerant may be causing some of the problem. It cant be helping.

Also, the systems are way oversized for the load inside the space. One system runs constant while others experience frequent on / off times. The frequent on / off of the outdoor unit reduces lubrication of the compressor which could be accounting for some of the Inverter over amperage alarms along with no compressor heat at 5.7 degrees. Some outdoor and Indoor units simply dont run as setpoint is reached, so they sit there as the load is the same in the entire building. Again, no compressor heat.

I was almost ready to fit compressor crankcase heat with a T-Stat. Energized anytime outdoor temperature is below 20 to 18 degrees. My only concern was I am afraid it may affect high compressor discharge temperatures.

Has anyone installed crankcase heat on large VRF equipment before? Would it have negative effects on the system?

Thank everyone.

Daikin had CCh issues with some of their VRV kit being underwattage. I suggest you add another one or do what we all did years ago -wire through an aux on the contactor or even wire it dol.

[Husky250]

Daikin had CCh issues with some of their VRV kit being underwattage. I suggest you add another one or do what we all did years ago -wire through an aux on the contactor or even wire it dol.

Thank you for the reply. I will add heaters on both constant and Inverter compressors. I am going to install on both compressors and both on T-STATS.