A product that has been available to automotive systems is now being used in residential applications. It is called a thermolube, and it might prove useful to you. As more of us are looking for ways to reduce our utility bills, more products are stating that they can help, and we homeowners keep searching for that golden bullet to help us out.
A thermolube works in your refrigerant line, so you may wonder how it would help lower your electricity costs. The refrigerant has to be pushed through your HVAC system. It goes through your exterior unit to the unit in your home that delivers the cool air. Basically heat is dumped to the exterior while the cool refrigerant takes heat out of the air from your home. The lubricant helps the refrigerant move through the tubing between these parts.
This lubricant will assist older systems more than a newer system. It is a way to help your older system live longer. As your system ages the parts do not move quickly and freely like in a newer unit. This could be due to rust or materials in the line causing it to stick. It has been found that a lube could help an older system improve by as much as 50%, while newer units may not experience any benefits. The brand which I am most familiar with is ICE 32 for cars. This brand has a residential version called ICE 22. You can look at this products frequently asked questions page for more information.
I am planning to test this product out soon, so I cannot speak about the products claims with great knowledge. Driving old Beetles for most of my life, I had no need for ICE 32, but I know a few people who claimed that this product helped their older cars, so I think it may be reasonable to assume that if you own an older unit, ICE 22 may help you.