HVAC-R Efficiency by Equipment Type

Every piece of cooling equipment loses efficiency in its own way. A 1,000-ton water-cooled chiller in a hospital basement, a 5-ton rooftop unit over a strip-mall tenant and a ductless VRF system in a hotel all run the same vapor-compression cycle, but they foul differently, are measured with different metrics, and respond to different maintenance. This hub takes each major equipment type in turn and answers the same practical questions: how does it work, how does its efficiency slip over the years, how do you measure that slippage, what maintenance actually moves the needle, and where an internal oil-film treatment such as CryogenX4 fits (and where it does not).

How to use this hub

Start with the page for the equipment that uses the most energy in your portfolio. For most commercial buildings that is either the chiller plant or the fleet of packaged rooftop units. According to the U.S. Energy Information Administration's 2018 Commercial Buildings Energy Consumption Survey, 55% of cooled commercial buildings use packaged air-conditioning units, rising to 66% in hot climate zones (EIA). Each page is written for a facility or energy manager rather than a design engineer, and each ends with a checklist of questions to ask before you approve any efficiency treatment.

Three ideas that run through every page

Heat transfer resistance adds up. Heat has to cross several layers to move between refrigerant and air or water: any film on the refrigerant side, the metal tube wall, and any dirt, scale or biofilm on the air or water side. The U.S. Department of Energy's Federal Energy Management Program (FEMP) notes that oil-free magnetic-bearing chillers gain heat transfer efficiency precisely "because no oil enters the evaporator or the condenser" (FEMP). In most other equipment, some oil does circulate. The oil fouling explainer covers the mechanism in depth.

Measure lift, not just temperature. Compressor energy rises as the gap between evaporating and condensing temperatures grows. FEMP's O&M guide estimates that a chiller uses 2.5% to 3.5% more energy for each degree of higher condenser temperature (FEMP O&M Best Practices Guide). Approach temperatures, head pressure and kW/ton show where that lift is coming from.

Fix the basics first. Airflow, refrigerant charge, coil cleanliness, controls and economizers cause large, well-documented losses. An internal surface treatment comes after those basics are right, never in place of them, and its effect should be verified with measurement on your own equipment. The Proof, Testing & Measurement hub explains how.

Where CryogenX4 fits

CryogenX4 describes its product as a one-time treatment, installed while the system runs, that lifts insulating oil film from internal heat exchanger surfaces and returns it to the compressor sump, while improving the lubricity of the existing oil. The company reports treating equipment from 1-ton air-cooled split units to 1,600-ton water-cooled chillers. Results vary by equipment condition, so each page here explains how to tell whether your equipment is a reasonable candidate and what to measure before and after.