Comparison Between DX-System and Child Water System

Can you give us some context, please?

DX, as in direct exchange.. as in heat pump?

Do you mean "chilled" water system?

Parental supervision is always required with a child water system, whereas the DX- system will operate independently.

Ravi,

In past also you had asked very basic questions. I once again would say, this forum is to discuss problems related to maintenance not to solve the home work questions. You could have got the answer through your Air Conditioning theory book or through the google. Any way you may like the answer as below:

Central air conditioners fall into two categories:

1) direct expansion (DX)

2) chilled water.

We can describe systems as below:

In chilled water systems, first water is chilled through a refrigeration plant then this chilled water is piped to the point of air conditioning, and air is chilled through local air handling units.

In DX systems air is directly chilled through cooling coil of the refrigeration plant.

This means that the cooling efficiency of the DX system is much higher than water chilled units, but because it is not always feasible to carry the refrigerant piping over large distances, DX systems are usually only used for cooling small buildings or rooms on a single floor.

DX systems comprise of three main components:

1. The Plant Room: This area of the DX system is comprised of the refrigeration system, compressor and condenser.

2. The Air Handling Unit Room: The refrigerant leaving the condenser in the plant room enters the thermostatic expansion valve and then the air handling unit. This area is comprised of the evaporator or the cooling coil, air filter and the large blower.

3. Air Conditioned Room: This is the room that is to be air conditioned. The ductwork running from the air handling unit filters the cooled air into these rooms.

While the efficiency of DX systems is higher than water chilled systems, the refrigerant piping cannot be kept at very long distance since there will be lots of drop in pressure of the refrigerant along the way and there will also be cooling losses. So DX systems do not always make sense.