Air Cooler system?

Recently I was looking for a good quality split type 8ton/hr floor standing package air conditioners and find out that most of the manufacturers are making these type of air conditioners with dual independent refrigeration circuits both in the Indoor and outdoor unit . These air conditioners the built with two scroll compressors rather than one 8ton/hr compressor. most of my experience is with single compressor air conditioners . My questions are:
1) Which is the better system for 8ton/hr split type air conditioning unit? is it with single compressor or double compressor?
2) Which system is better for long pipe length distance?
3) does two compressor starts at a same time or one after another?

Can any body help?

Generally the larger units are now split into 2 circuits. This is primarily done for to achieve higher efficiency ratings. The way the system operates depends on how you wire the controls. On most systems it will be operated as a first and second stage for comfort cooling because of load fluctuations. If you are using it for process cooling and the load remains consistent, then you can have both stages come on at once.

For the piping... That too is up to you. Cost may be cheaper to Twin the circuits and only run one appropriately sized line set. I have done this before you just need to make sure that the compressor oil sumps can be equalized (run a peice of copper between the compressors below the oil level to equalize the oil levels between the two compressors). In this instance twinned in this way both compressors will come on at the same time.

Hi,

There should be no problem in using system having two independent circuits, in addition they give better efficiency and more advantageous than the single circuit.Mostly, one compressor starts after another and have no idea about how they can be start at the same time.8 Ton package units can be used for piping upto 30-35 foot , if you want to increase the length of piping , then you have to charge some more refrigerant in the system.I don't know much about Bangladesh ,but here in India generally we use BlueStar package units.

Have a nice day.