Refrigerants are chemical mixtures of various substances. They normally undergo various states of existence, from liquid to gas and back during the HVAC cycle.
Due to the destructive effects of the compositions of refrigerants on the environment, the EPA has banned the use of certain refrigerants altogether. These banned refrigerants were to be replaced with new ones, and mixing refrigerants became totally illegal.
In the wake of this, new refrigerants have come into vogue, though none of them can be said to be one hundred percent safe for the environment.
Refrigerants can be broadly classified into the following:
- Chlorofluorocarbons (CFC) – These refrigerants contain chlorine. They’re banned by the EPA. Since then, the conversion of the existing HVAC systems using them onto other refrigerants is still in progress.
- Hydro chlorofluorocarbons (HCFC) – These refrigerants have been deemed fit by the EPA to temporarily replace the CFCs.
- Hydro fluorocarbons (HFC) – Though these refrigerants don’t contain chlorine, and are considered less destructive to the ozone layer, they still assert a dire impact on global warming.
Considering the harmful effects refrigerants in general have on the environment, it’s impossible to gauge the level and extent of damage mixing refrigerants such as these causes. So, mixing of refrigerants isn’t something I advise.
Now with that said, contrary to the existing and new laws, this practice is happening. In such a scenario, one should be aware of what happens when refrigerants are adulterated or mixed (think of it as an advanced hvac tool kits lesson). Let us look at some of the effects of mixing refrigerants:
- Recycling of mixed refrigerants isn’t possible
There’s no process to recycle or filter mixed refrigerants, so they must be incinerated (which will incur charges from the authorities).
- Lack of pressure temperature charts
Accurate charging becomes impossible due to the lack of availability of pressure temperature charts for the new blend of mixed refrigerants.
- The rate of oil return to the compressor
It’s not possible to know if the new blend allows for proper oil return to the compressor, which may result in its failure.
- Likely reduced capacity and lower efficiency
The new blend will most likely result in reduced capacity and lower efficiency of the system.
- The cost of full replacement to pure refrigerant
Once a refrigerant is adulterated, it’ll need to be completely cleaned out and replaced with a pure refrigerant.
Taking into account the risks listed above, mixing refrigerants appears to be a risk not worth taking. The best option would be to switch entirely to ammonia, carbon dioxide or hydrocarbon refrigerants, which are among the emerging group of natural refrigerants.