Installing a r410a condenser on a R22 coil and furnace

Efficiency

The 410a evap coil has about a 30% larger surface area than it’s R22 counter part. Does that make it 30% less efficient when paired with a 410a condenser? We don’t think so but we are pretty sure that you are not getting the full 14 SEER value by installing only the condenser. Customers did report that month over month and year over year that they saved $30 to $50 over there old condenser while others said it reflected no electrical use savings at all.

Reliability

Our first 410a condenser install that was paired with an r22 coil was done in June of 2011. It runs on about the same amps today as it did the day we installed it. The customer who has owned the home since new says it works as well as the old one did. There is no reason to believe that the 410a condenser only install will have more problems, be less effective at cooling or will not last as long with or with out a matched coil.

Why Does a r410a Condenser work on a R22 evaporator coil?

Both refrigerants, R22 and r410a work off of pressures. Mor specifically they work off of a balanced ratio of vapor and liquid pressures. Though these two refrigerants need different pressure they both use incrementally similar pressure ratios.

The other factor that you may hear some HVAC technicians say is the Evaporative coil can not handle the higher pressure. This is complete hog wash. Anyone that says this does not know how an AC works. You see the oldest evap coils for 25 to 50 years ago were pressure tested to 350 PSI. The newer coils are pressure tested to 500 PSI. Unless you have a heat pump, your coil will never see pressures above 250PSI. Moreover, the operating, running pressures are closer to 165 PSI at the coil.

Contamination

Based on a 9 year history of this practice and 2 dozen plus warehouse test mutts, we know conclusively that there is no more risk of cross-contamination from R22 to the new 410a with a condenser only change out than if you were changing the evap coil too.

It is widely practiced by every c21 HVAC contractor here in Las Vegas to remove the evaporative coil and leave behind the existing cooper line-set. When the designers of the new 410a system engineered these systems, they knew that the cooper lines would be reused. They must also have had some reasonable assumption that some r22 and 410a oils, POE and Mineral, could and even would mix. The systems were built with tolerances for this.

Oxygen and moisture contamination is the biggest killer of r410a compressors that we see today. The old R22 compressors were not so picky. A tech could do a poor job of installing the R22 condenser and the unit would last for 10 years or more. With r410a units, the installers must have there process dialed in tight. No more sweep charging or fast flush. Each system must be vacuumed down to 350 – 700 microns. The Las Vegas dry climate makes this easy on most summer days.

Using R11 or other line cleaners

We have tested with and without line set cleaners and we have no conclusive reason that makes this a required practice. At present we have more compressor failures where cleaners were used than those without. Using high-pressure nitrogen to blow out the lines has proven most effective. Some manufactures will void warranties were line set cleaner was used.

What happens when 410a mixes with R22

We clear the lines completely of all R22 and oils before we install a condenser. It is part of the protocol and has been for more than 5 years. we do it the same way everytime. For that reason we have no compressor fails do to contamination.

With that said, we still get the question about the cross-contamination of refrigerants all the time. The real answer is, we can not say for sure what the long term effects are. There have been a few experiments where we set out to make a unit fail as a test. We deliberately added r22 to a 410a system that was cooling our warehouse. That was 5 years ago and every morning for 5 years, I go in, turn on the lights and feel the cold air hit me as I close the door behind me.

There was also unit that we found having a mix of R22 and 410a as the result of another companies mistake. Though that AC did not work well it did work. You can read the detail of the cross contamination saga on the article we posted.

When we do a condenser only install we clear all the oils and  r22 from the lines. We then put the system under a vacuum and remove any remaining particles or moisture from the system. When we are done we are so sure that the system will work and work well that we offer a labor warranty of 10 years.

I think it is important to remember that R22 and r410a are made of the same chemicals just in different ratios. Though the oils are different, Mineral and Polyester are not going to contaminate each other.  They will not mix but that does not cause a problem. One will set on top of the other much like two different weights of motor oil will do in a car. Does this hurt the engine? Not at all.

Home Warranties and condenser only installations
 
If you have a 410a condenser installed on your home and you have a home warranty it is unlikely that they will make any further repairs to your system. On the other hand, If you are looking at installing a new condenser, they may have already given you the boot. If you purchase a new condenser for your home you can rest assured that the manufactures 5 to 10 year parts warranty and Fast Affordable Air’s 1 to 3 year labor warranty has you covered.