HVAC: Air Cooled vs. Water Cooled units
Friday, January 20th, 2012 at
10:24 PM
Filed under HVAC System Efficiency.
Question:
I am hearing a lot about maintenance issues with water-cooled condensing units and the local distributor is telling me that I can save a lot with a water-cooled HVAC unit. Can you help me sort out all costs and benefits to see if air cooled or a water-cooled unit is cost effective?
Answer:
There are a lot of facets to this question. The general claim that Water source air conditioners are more efficient than their air source counterparts is definitely true due to the improved condenser efficiency. However, this increased efficiency comes at a cost. Water Source AC units require a condenser water loop, pump and a heat rejection unit. Boilers may also be required in most (if not all) of the sites that operate with water source units so as to prevent refrigerant freezing issues during winter.
Lincus engineers have seen that water source heat pump units and their economics work well when the site requires multiple smaller HVAC units. An example would be condos where each unit requires anywhere from 3-10 tons. The average cost per ton for water source heat pumps between 3-10 tons is roughly $ 1,100 per ton. Another example would be facilities where packaged/split AC units cannot be installed due to space constraints. In cases where there are multiple units, the cost of installing the ancillary units (boilers, pumps, cooling towers, piping, etc) may also be justified due to the number of HVAC units that you could possibly connect in one common chilled water loop and the efficiency increase on all these units. Water source air conditions will definitely not pay off well in all other circumstances which is why, the air source AC units are the units that we commonly see.