Refrigerant Additives: “Snake Oil” or Do they actually work?
As a leader in HVAC of Houston, we at Pickett Heating & Air feel that it is our duty to inform everyone when there is a question regarding anything HVAC-related. Today I want to talk about refrigerant additives, how they work and when they should be applied.
Refrigerant additives were derived through a project of NASA with a goal to improve the efficiency of their HVAC in all of the NASA facilities as well as their fleet back in the late 1990’s.
Since then, various spin-offs of the product have been sold to the public all over the world.
With a background as a Hydraulic Fracturing Engineer for Halliburton, I did a little research on the additives and immediately recognized how it works because we used similar practices to improve well productivity. This additive is what you call a “surfactant”. A surfactant is used when there are two dissimilar phases (either two fluids or a fluid and a solid) that in their “natural” state, can’t easily or at all permeate through each other due to high surface tensions. In other words, the two substances for all practical purposes, repel each other. Dish soap is a good example of a common household surfactant, but don’t let that confuse you. There are tons of surfactants out there, they all work in different environments and they react differently in different environments. In an oil well, oil that is underground gets “blocked” from the water in the channels and needs a surfactant to lower the surface tension of water for the oil to pass by and be recovered on the surface. In an HVAC refrigerant circuit, there is both refrigerant and an oil lubricant of some sort. Over time, the oil actually forms a coating along the walls know as “oil fouling”. Oil fouling of a refrigerant circuit causes a decrease in heat transfer between phases. (Majority of HVAC applications this is air and refrigerant) There is a lot more to how surfactants work regarding particle charge, van der Waals forces, hydrophilic, hydrophobic, etc., but for all practical purposes of this article, this surfactant is going to increase lubricity of a refrigerant circuit and remove the oil fouling.
According to ASHRAE, performance is degraded by as much as 30% due to the build-up of lubricants on internal surfaces. Higher percentages of up to 40% have been observed in systems 20 years old or older. When the additive is added to a system, the additive will bond to the metallic wall, preventing oil fouling and eventually removing the existing oil fouling. When the fouling is removed, this now maximizes the refrigerant’s surface area and ability to transfer heat through a coil from the inside of the circuit.
THAT BEING SAID, oil fouling is only a PIECE of the problems that can arise in an HVAC system. A dirty coil, fractionated charge, non-condensables, air leaks, refrigerant leaks, failing expansion valves, controls failures, the list goes on and on of the types of problems that can occur. NONE of these problems can be fixed with an injection of a refrigerant additive. Therefore, as a consumer, it is STRONGLY recommended that you consult an experienced HVAC company before just ANYONE touches your HVAC system. By the way, there are many additives out there, don’t you think it is weird that the manufacturer doesn’t start with the additive in their system? I will let you come to your own conclusions on that one.
In my HVAC technical opinion, I would use additives, but ONLY on those systems that are aged and unable to reach a good temperature split after we have maintained them to our best ability. NEVER trust anyone who says it is a “fix all” because I assure you they are very much not even close to being correct.
August 24, 2017