Carrier Rooftop Packaged Units, Using Heat Xchanger to improve efficiency?

[Fett]

Afternoon Gents,

An outside company came to the company I work for. We have a large facility and a large number of rooftop packaged AC units. This outside company offered to install a heat exchanger on each AC unit's liquid line which is then tied to a cooling towers water supply. My company told them no because the bid was very high, but instead want me to do this job in house.

They claimed that this would reduce condenser pressure allowing the compressor to run less time and less hard.

Is this viable/would this actually increase system efficiency and reduce power usage?

This building has 19 packaged units ranging in size from 4ton to 12ton. Also there are 23 split units, of which the condensing units are also on the rooftop. For the standard warehouse section of the building there are 42 Evaporative coolers only 24 of that actually get used.

[Magoo]

Hi Fett.
increasing sub cooling in liquid lines will increase evaporator performance and make compressor work harder and probably increase discharge pressure and draw more power. All dependent on water temperature being applied into heat exchanger. On average every two degrees C increase in sub cooling will increase TXV performance by 1 %. Then the increase in feed water temperature to cooling tower will increase water usage and reduce effective cooling capacity of cooling tower.
Ask the contract company offering system to provide projected savings by applying HXs and forecast savings in energy etc.. If roughly a two year pay back on expenditure then viable. Then do it your self.
magoo