Refrigerant Additives for Non-Efficient Struggling Air Conditioners
During the normal operation of an air conditioning unit, refrigerant circulates through a piping system and is compressed and expanded to transfer heat out of a building. During this process, a small amount of oil comes out of the compressor and mixes with the refrigerant. Over the years as the oil-refrigerant mix travels through the pipes, a small layer of oil can collect on the inside of the refrigerant piping. This layer of oil acts as an insulator and inhibits heat transfer through the metal walls of the pipe. The diminished heat transfer results in an overall drop in equipment efficiency as the unit must work harder to transfer heat through the insulating layer of oil and then through the metal pipe. This condition of oil accumulation is called “oil fouling” and over time can decrease equipment performance by as much as 30%.
When oil fouling becomes a serious problem, HVAC technicians have the option to inject an additive into the refrigerant circuit to reverse the fouling. Additives typically come in two forms: Polarized Refrigerant Oil Additives (PROA’s) or Synthetic Refrigerant Additives (SRA’s).
PROA’s were the first generation of additives and introduced in the mid-90’s. PROA molecules introduced into the refrigerant system electrostatically bond to the pipe’s interior walls and displace the accumulated oil restoring the heat transfer capability of the pipe. Early PROA’s contained chlorine or sulfur that chemically attached with moisture in the refrigerant and became acidic. The acid slowly ate away the internal components of the compressor, valves, and piping resulting in severe equipment damage. PROA’s also chemically broke down after several seasons and additional PROA needed to be added to keep the oil fouling from coming back. Some companies still sell PROA’s (i.e. – Zec Lubrication, ArtiKool, PROATEQ, KOOLBlue), but all make special note that their product does not contain chlorine or sulfur and does not break down to form an acid.
Cold-Plus works similar to a PROA, but its website specifically says it is not a PROA. Cold-Plus works by coating the internal pipe surface with “Cold-Plus Polymers”. It does not require ongoing applications and does not break down to an acid.
Unlike PROA’s, newer SRA’s do not collect on the internal surface of the pipe to block oil fouling. SRA’s continually flow though the pipes mixing with the oil and refrigerant. SRA’s are a blend of different chemicals or catalysts with each performing a specific function. To clean up and prevent oil fouling, SRA’s break down the surface tension forces between the oil and metal pipe wall preventing the oil from sticking. Other catalysts within the SRA increase the lubricity of the oil also keeping the oil from collecting on internal components. Some SRA manufactures (ICECold, bluemaxx, for example) promote a third catalyst that changes the boiling point of the refrigerant to improve the heat transfer capability of the refrigerant.
All additive companies claim an increase in air conditioning efficiency of anywhere from 10% to 25% primarily by removing and preventing oil fouling. One SRA company we found, PowerKnot, provides a guarantee in writing of at least a 10% efficiency gain on any system using their product.
Oil fouling is a common and serious problem in residential and commercial air conditioning systems. The accumulation of oil on the inside surfaces of refrigerant pipes can significantly reduce system efficiency. HVAC technicians have choices of several refrigerant additives to inject into the piping system to remove fouling and restore system performance.
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