Side Stream Filtration

Evaporative cooling is the most energy efficient product in an air conditioning system.

Cooling towers and closed-circuit fluid coolers are common in many HVAC systems. They work by evaporating part of the circulating water generally around 1% of it and as such the latent heat required for evaporation is taken from the circulating water and cool it down.


The evaporation happens by creating a thin layer of water and forced air over these layers and saturate the air with evaporation. This is great way to cool down water and have an efficient cooling system.

However, the air has its airborne contamination and leave them inside the water. In fact, the system works like an air washer. Also, the dissolved solids inside the circulating water will not get evaporated and stays inside the circulating water and gets concentrated.

These contamination as well as the concentrated solids inside the water such as CaCO3 will residue inside the fill media and travel with water inside the condenser of the chiller or

air conditioning system and will reduce the efficiency of them. This means a higher operating cost, increased maintenance and reduced life span of the system. Also, by fouling inside the condenser tube tubes the pump pressure goes and this will add to the cost of operation. As such it is necessary to have filtration on the circulating water.

There are three major types of water filtration:

  • Full flow filtration
  • Slip stream filtration
  • Side stream filtration

In full flow filtration we filter the whole circulating water. The cost of such is filter is high and it is not necessary and optimised for a HVAC system.

In Slip stream we take a portion of the water filter it and will return it back to the system. This not very common for HVAC system.

The most common system for HVAC and open cooling towers is side stream filtration. In this system we take a portion of the circulating water, filter and pump it back to the basin of the cooling towers.

The cooling tower basin is equipped with sump sweeper piping with high flow eductor nozzles. This piping is connected to the outlet of the filtration with the pumping water sweeps the basin and push the debris towards the suction point of the filtration. The sucked dirty water will be cleaned by filter and will return to the basin of the cooling tower.

Vesta Group can design, supply, install and maintain the sump sweeper piping with side stream filtration for any brand and make of a cooling tower in the market. For further information please get in touch with one of our friendly customer support team.