How Much Refrigerant for the Air Conditioner Question: What amount of Freon would it take to service a unit that services a 1200 square foot residential house if it were completely depleted?

How Much Refrigerant for the Air Conditioner

Answer: We get questions like this a lot in our email and this is not easily answered especially when we are talking about charging an air conditioner or heat system. No matter how the system lost its charge of refrigerant (many people refer to it as Freon which is technically incorrect) there are many things you need to know before attempting to charge the air conditioner or heat pump with refrigerant (or Freon if you prefer).


How Much Refrigerant for the Air Conditioner

1) HVAC Refrigeration and Triple EvacuationFirst off the name Freon is a registered trademark of Dupont Corporation for the refrigerant commonly used in residential and light commercial systems. The refrigerant is R-22 and it is currently being phased out because of the Montreal Protocol that phases out refrigerants that have been deemed unsafe for our environment.

R-22 contains Chlorine and that has been shown in a laboratory to change ozone or O3 to O2. Using that logic a group of nations got together back in the early ’90s and decided to phase out the production of these products. As of 2020, R-22 will no longer be produced. In fact, it is very difficult to find any manufacturer that produces R-22 now at the time of this writing.

Most residential and light commercial systems that use R-22 are being replaced with newer systems that use R-410A which does not contain Chlorine. It is very important to use the correct type of refrigerant to charge the system as they each use different oils and are not compatible with each other. Irreparable damage can occur to the compressor if the wrong refrigerant is used.

2) The next important factor is that the system must be properly evacuated before attempting a recharge. If the system was discharged and you do not know how it lost its charge then it has a refrigerant leak. The refrigerant leak must be repaired before attempting a recharge. In fact, even new systems that are installed are leak-checked and properly evacuated before the charging process begins.

Why would one want to charge a system when you know it is simply going to leak down again and cause serious problems? Once that has been completed then proper refrigeration system evacuation procedures must be done otherwise the system will not function properly and possibly lead to catastrophic failure.

Skills and Proper Tools

3) After the leak is fixed and the system is properly evacuated, you need to charge the system. This is not an easy process for most people as it requires skill. The charge cannot be done by the square foot of the house or even the size of the HVAC equipment. It must be done based on current environmental conditions including outside air temperature and inside air temperature including dry bulb and wet bulb temperatures. Additionally, a basic check of the system should include airflow.

No dirty air filters or anything else that would impede airflow. A manufacturer’s chart needs to be followed based on the pressures of the system and the indoor and outdoor air temperatures along with the temperature of the suction line or condensing unit leaving temperature depending on the type of metering device you are using. If you have a fixed orifice metering device you will use a different method to charge the system than if you have a thermostatic expansion valve (TXV) metering device. So you need to know what type of metering device you have to properly charge the system.

4) If you know all of the above information then you need to have the proper tools to do the job. You need compound gauges, a vacuum pump, nitrogen, a sling psychrometer, a method of taking an accurate temperature of the refrigerant lines (preferably an electronic thermometer), and other basic hand tools to charge the system.

5) Lastly, according to the Montreal Protocol (mentioned above) anyone who handles refrigerants needs to be licensed to handle refrigerants. The fines for not being licensed begin at $10,000.00 (in the USA) and are regulated by the EPA.

How Much Refrigerant for the Air Conditioner - Conclusion

While charging a system is not rocket surgery there are certain skills required to do it properly. There are proper tools needed to do it correctly. If the system is undercharged or overcharged then it will not function properly and it is very possible you will cause irreparable harm to the system.

The average residential air conditioner takes approximately ~3 to ~5 lbs.

After explaining all that do you not think it is best to call a professional HVAC technician to charge the system?

How Much Refrigerant for the Air Conditioner - HVAC

How Much Refrigerant for the Air Conditioner