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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) 
First 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
Technical Resource: Refrigeration and Air Conditioning Technology
A very good article, I don’t understand why anyone would be upset. I am an HVAC technician doing some reading of your articles and find it strange people are complaining about their own google searches. Hats off to you sir, thank you for your work!
What a useless article. And dear God, you are incredibly defensive in the comment section. Protip: if every comment is essentially the same gripe, maybe *you* are the one who’s wrong.
I know in clown world reading comprehension is difficult for clowns. Maybe its the clown shoes or clown nose?
Just wanted to get a guesstimate on how many LB of refrigerant my house might take, as not to be ripped off, found a bunch of “don’t do it” answers. Okay I won’t, now approximately how many lbs? 3? 30? 300?
Likely not 30 or 300 lbs. On average, a residential system will have approximately 4 to 6 lbs depending on the tonnage of the equipment. If you look at the condenser tag where the model number and serial number are located it should give an amount in lbs the unit was charged with at the factory. Depending on the length of the line set some additional refrigerant may be added to the system (for line sets over 25 feet). There are some other factors but that information on the data plate on the condenser will give you the ball park. Also, not every system needs a full charge. Some just need a minor tweak to get the pressures correct.
This is a very misleading title! I did not attempt to charge my a/c unit. I called a reputable company who sent a “trained professional technician” who spent ten minutes on-site adding a little Puron before saying “it really didn’t need Freon”. I told the dispatcher that I had noticed damage to the return air box when I called. The “trained professional technician” never examined the box and told me to call if that didn’t fix the problem. Two weeks later, the company’s construction crew repaired the return air box and all’s well. The bill I received charged me for one pound of Puron which my unit did not need. I clicked this article to get an idea of the Puron capacity of my unit to determine if I was over-charged for the Puron I didn’t need. Perhaps it’s a minimum charge unit. I don’t know and I still don’t after reading this article.
Please don’t try to protect me from myself, especially with a misleading title. Also, own your mistake. You mislead us in your effort to save us from ourselves. Just retitle your article more reflective of your efforts to warn the world of the perils of DIY a/c charging!
Thanks!
Go to school and learn refrigeration, thermodynamic basics, psychrometric charts, psychrometrics, dry bulb T, wet bulb T, superheat, subcooling, enthalpy, zeotropic, azeotropic, pressure temperature for different refrigerants, the refrigeration cycle, be able to explain refrigeration theory and airflow for air conditioning and heat pump systems, have basic knowledge of refrigeration valves, compressors and components including electrical parts and controls plus purchase a vacuum pump, refrigeration compound gauges, refrigeration recovery machine, a recovery tank, amp and volt meter, digital temperature thermometer with extended leads, infrared thermometer, and a pocket thermometer. Lastly, when you send me your EPA section 608 refrigeration license (which requires a class) with type 1, 2, and preferably type 3 certifications. After that we can talk about it. I’ve clearly explained the TITLE and the purpose of the title in the article and in subsequent replies to comments.
Nowhere within this article do you speak on directly, or even reference, any quantity of coolant for any type of system… This is not a very well laid out article, as it’s title is quite misleading… You are also incorrect about a number of things, first being that charging any system is any more difficult than a middle school algebra equation…
I’ve changed out bad compressors because the system was incorrectly charged by someone who thought they knew what they were doing – whether overcharged or undercharged it can be and oftentimes is detrimental to the system. I’ve seen technicians who have gone to school for a year and still do not know how to correctly charge a system. You also need a license to handle refrigerants. Every system is different and sometimes different methods need to be employed. If you need a charge or THINK you need a charge call a professional HVAC technician.
case of deceptive and misleading title
How so?
I understand that there are many safety, environmental, and legal concerns to take into account in this situation, but why would you list them in place of, rather than in addition to, an actuall answer to the question? Even a very rough estimate or average for residential units, with a disclaimer, would at least have given the question the respect it is due. Instead this article is deceptive in that it alludes to being a source of information that it does not actually provide, drawing in views from search engines that it does not deserve. This article would be a fantastic response to a question along the lines of, “Should I fill my AC unit with refrigerant, or hire a professional to do it?”, in which case it would show up on web searches appropriately. Please consider revising the question, or answer, of this page, or let me know if my view on the matter is mistaken in some way. Thank you for your time.
I think the last few sentences explain the situation and I think I was nice about telling people they shouldn’t be charging their system unless they have the proper tools and skill set to properly charge the system. Someone sent me a question via email (actually several people ask this question a lot) and I believe I answered it with my best advice. I can say that I’ve been to some calls where the customer tried to do it themselves and ended up causing irreparable harm to their system that ended up costing them a lot more than if they would have called me in the first place. So when I respond I almost always am looking out for the best interest of the consumer. If not, then I advise caution usually more than once and give them information about what can happen if they get it wrong. I’m not trying to scare anyone just looking out for them as I’ve seen it too often in the field where someone got a little overconfident and ended up causing problems and costing more than if they would have simply called me or another HVAC tech in the first place. There are some trained techs who can’t get it right so I’m pessimistic a consumer who does not have the proper tools or training will get it right.
Lastly, I do not control Google or any other search engine. If I did I would be number one for every search and be wealthy beyond anyone’s imagination. I do give some thought to the keywords used but sometimes I just take them off the top of my head and then optimize the page for those keywords. On occasion, I will do keyword research to target specific keywords based on certain datasets I garner from my research. This article was off the top of my head and I did no deep or detailed research for it. I suppose it could be confused with the cost of refrigerant because of the “How Much” but other than that I think its an apt name for this article.