Recharging AC With Propane


As the summer heats up an air conditioning system is a necessity in many climates. [Grayson’s] system suffered some damage over the winter that caused it to vent its refrigerant, avoiding an explosive situation. Before he can chill out inside he’ll need to recharge it and he’s chosen to use propane in his cooling system. According to our friend Google this is not his original idea, but has been done many times before. [Grayson] makes the point that although propane is flammable it’s not necessarily any more dangerous in a fire than Chlorodiflouromethane, or R22, which is the nasty little gas that fled his system for its new home in the upper atmosphere.

The video above includes a brief explanation of recharging the system and the tools needed. We’d need to mill this over for quite a while before working up the gumption to give it a try. For now we’ll stick to [Grayson’s] more pedestrian hacks like making some servo motors sing or easing our yard work woes.

301 thoughts on “Recharging AC With Propane

  1. propane is a refrigerant yes, however, r-22 is not a dangerous gas as this is. in addition to being flamable, it could leak out and cause a fire when a contactor closes and creates an arc across the contacts. this person, in my opinion, is dangerous and this should never be done ever. i work with refrigerants for a living and i have heard and seen some dumb things in the past but this takes the cake. stupid thing to do and i am in agreement. this is a hack done by a hack!

    1. what sorta volume are we talking in the lines? I cant imagine its enough to be that big of a threat. Maybe a fire ball in a room but I question if it would even light the room itself on fire. esp if it was a basment with no carpet and exposed block. There isnt going to be enough gas to make whole house go boom. as further evidence you are erroring on the side of nutz…it takes the right air to gas mixture. Mythbusters constantly had issues getting this sort of explosion myth to go off with out modifying the house/chamber/conditions set in story/myth that was susposed to blow

    2. Guess you never worked with R290, then. – 2 and 3 hundred pound industrial systems. (If you didn’t know R290 is ummmmm PROPANE- Pure PROPANE.

      In every other country in the world they have been using straight Propane and it blended with butane for decades,,,,and not one explosion….(You work for Dupont? – Real strong lobby against R290 and for R410 $$$$)

  2. What about LPG powered vehicles, of which there are hundreds of thousands? Very similar risks in an accident or potential leak situation, only significantly more gas to leak. Yet considered perfectly acceptable and DIY fitment is roundly approved.

  3. Oh Noes! The Nanny Police has decided that this is tooo DAAAAANGERWUSS for us widdle people to know about, therefore this BAAA-AAAd information will be banned and surpressed!

    …or not. Right on Hack-a-day, kudos for having the huevos for posting this “hack.” Knowledge needs to be free and unfettered and available to all. The decision whether or not to actually implement what is learned needs to be left to the individual. PERIOD.

    Life, liberty, and the pursuit of happiness and KNOWLEDGE.

    Thank You.

  4. The compressor couldnt care less which gas it is pumping, freon or propane. As long as there is still lubricant in the system the compressor will pump away for a long time. The compressors are just rotary vane pumps.

    An internal spark cannot cause an explosion. Go back to chemistry class! You must have an oxidizer for ignition to occur.

    If a system comes up to air in the very least the dryer will need to be replaced. Putting a vacuum on a system will not get rid of all the water vapor. Anyone that has worked with vacuum systems will agree. Water attaches itself to everything an does not like to let go.

  5. I have worked in the HVAC/R trade for 20 years. . . This is a very bad idea, I hope I’m not the next one to try brazing a leak on that thing. Also, if it develops a condenser leak, there is a VERY real possibility that an arc from the contactor will cause a fire. But other than that, it should work fine. Propane is a component in a lot of retrofit refrigerants anyway. . . It helps with oil return to the compressor. BTW, if the original leak was caused by ice buildup, you have another problem to be investigated.

    1. One of the common reasons for a leak is “trauma” to the system. Outside mechanical injury/damage. I can’t think you’d braze with pressure still in the system. System pressure down to atmospheric and I’ll braze your system for you any day.

    2. 20 years as a refer man and never worked with R290? Who did you work for Bob Villa? Just so you know R290 is propane and used widely in “big” systems.

      The only thing standing in the way of widespread use of 290 is Dupont,,,,and FYI there are several domestic refrigerators already on 290 (Not the old absorption chiller types either.

  6. I can confirm what megaton just said. I’ve had 10 year of experience in refrigerant systems and this is a VERY BAD IDEA.

    It is indeed true that propane is a component in the gas mixture used in refrigeration systems, BUT it cannot be used safely to retrofit an installation. explosion being the greatest danger, obviously.

    Refrigeration systems are designed and pressure-tuned to work with a specific gas.
    As all of you should know from chemistry class, different gasses have different pressure points and temperatures at which they become liquid and vapor. The whole idea of a well designed refrigeration system is to take advantage of these critical evaporation and condensation pressures and temperatures inherent to the type of gas it was intended to be used with.

    It should be clear that the thermodynamic properties of propane are substantially different than those of the most common refrigeration gasses, such as R-134a , FX 56 , R12 , the older R22 etc…

    Even if you decide to go ahead and take the risk of burning down the house and violating your fire insurance contract, you’re not taking away the cause of your problem at all.

    This is something you need the right materials for : manifolds, the tap wrench etc…. If you’re confident enough, at least buy the right refrigerant.

  7. @LilJon:
    That what you have adjustable valves, pressure-temperature charts and common sense for.
    As long as you are aware of what you have to change if you change the refrigerant, everything should be fine.

    Also Gas is not zomfgExplosionRUUUNNNN!!! Its, as pointed out by others, quite difficult to get gas to explode.
    And for gasleaks: That what you have sensors for.

  8. Has it escaped your notice that lots of houses and already have pressurized tubes of propane and methane running through them?
    Propane sold commercially has an odorant (ethyl mercaptan) to make it easy to detect leaks at LOW CONCENTRATIONS.
    The main safety issue I see is that propane is heavier than air and can pool in an enclosed space. If you’re worried about this, install a propane detector and you’re done.

  9. If refridge. technicians would stop charging exhorbitant fees for recharge/minor repairs I suspect people wouldn’t take these routes anyway :) Recently quoted £350 UK for replacing a hose (cost 75) and leak-check-recharge with R134.

  10. I have all of the proper tools, equipment, materials, technical knowledge, and common sense required to make this retrofit work. I however cannot afford to lose my licenses. This will work from a technical standpoint, but not a practical one.

  11. This is a horrible idea IMO but the video tutorial on how to charge a system properly was a pretty good one. Just substitute the propane for R22 from you local street dealer. If you look hard enough you can get R22.

  12. There seems to be a lot of people on here that watch to much tv. grab your BBQ tank get out in the back yard and see what it realy takes to make a propane explosion. Sound unsafe? Good luck getting past losing your eyebrows.

  13. :S Wow so many ignorant posts.
    Propane is used as a refrigerant all the time. I’ve used it in a camping fridge. Sure if it leaks it could pose a hazard, but it won’t explode unless the mixture is just right.

    You could get hit by a car if you leave your home…just saying survival is never guaranteed anyways.

    I think the main thing is making sure the compressor is compatible with propane, over time it might degrade it if it isn’t.

    Also, I have a propane hotwater heater, stove, and fireplace. All have had pilot lights go out. Never have I had a fireball, let alone an explosion. Propane leaking out of a AC isn’t a big deal.

  14. Propane needs oxygen to combust. There isn’t any in a hermetically sealed system.

    If it did leak, like any pressurized container of propane with a small leak/ orifice, it could be lit & used as a burner/heater. Think propane torch/stove/bbq. NOT A BOMB!

    As previously mentioned, Gasoline is far more hazardous. Many vehicles have DIY propane fuel systems. Many houses have Natural gas or propane lines coming into them for cooking & heating, many of which are diy…

    The purpose of the vacuum pump is: A)to get the moisture out B) to hold a specific vacuum for a specific period of time so as to verify there are no leaks.

    While most refrigerants are not flamable, they do contain a good deal of oil. A leak would let an atomized mixture of oil escape into the atmosphere. I hear it can make a dandy fire ball. (just do a search on George Goble).

    My understanding is that propane usage is fairly common in Europe & Asia. Also in use in stationary & industrial refrigeration in the US.

    I built this propane powered beverage cooler:

    Using propane Actually lowered the critical temperature & made the compressor run cooler(less load).

    A good intro to the subject:
    A list of the multitude of things which can be used as a refrigerant:
    (Does the EPA know about this R718 stuff? Sounds pretty dangerous!)


    Even frickin’ greenpeace likes it:

    Also, for those thinking rv refrigerators use propane as a refrigerant, probably not. Most use Ammonia. They use propane as a heat source to boil the ammonia. By the way, ammonia vapors of this concentration are very deadly, if a leak does develop.

  15. This probably would be safe some something like a small refrigerator or window AC but a heat pump is going to be very dangerous because of the amounts of gas it can contain.
    Plus you have a close box full of relays and contactors.
    A leak in the attic when it’s in heat mode would be a disaster esp if the booster heater is engaged.

  16. @o4tuna;) R-718 (dihydrogen monoxide) is probably the most dangerous refrigerant EVER! This stuff is used in everything from manufacturing methamphetamine to nuclear warheads. . .Criminals and street gangs use this stuff on a daily basis! It is found in ALL cancerous tumors! It is responsible for thousands of deaths every year worldwide! Wanna buy 1000 pounds of it?

  17. I’ve been shopping around to get my AC fixed.

    I’ve also been looking at building myself a projector so I’ve been on LumenLabs and managed to stumble upon this.

    I borrowed the gauges from someone at work.
    Borrowed a vacuum pump from another person (discarded industrial one, AWESOME).

    $5.12 worth of propane from walmart and some hoses and hose clamps. My AC is working… It took me 20 minutes. THANKS.

  18. @ megaton

    probably Electrolysis of some sort is used to split the hydrogen from water.

    while water is frozen into blocks of ice for camping coolers it by it’s self does not refrigerate.

    also liquid oxygen could be used except that the condensing point probably is so extreme that only industrial process can do it.

  19. I had already scheduled a technician to come top my system off and when I saw this hack I cancelled went to walmart for some propane and now my ac is working great. Thanks this is awesome. oh yeah nothing blow up either.

  20. Service man could not find R22 leak & heat pump could not keep house cool. After propane was installed, current was reduced 27%, temperature drop was about 13 degrees >. Heat pump with propane could keep 72 F while cycling off-on. Heat pump died several years later, near age 25.

    GMC pickup also did several years with propane installed. Much better cooling.

    If you want to do it “properly” use Enviro-Safe 22

    1. One more thing. – Propane molecules are bigger then the other refrigerants and will not leak out of a crack or other opening that will pass R-22 and 134A. — (Not that it will fill a large hole but on a microscopic level it is a fact.)

  21. Isn’t the point kind of.. if you need to recharge the system there IS a leak? Shouldn’t you address the leak before pumping more refrigerant in? Propane or not?

  22. @ Deerjerky Leak was thought to be in 130′ freon tubing under concrete slab. Heat pumps had been moved when 2 rooms added to house. Propane installed by me cost much less than freon, >> repair or replacement.

  23. eric, standard split system installation usually don’t have more than 20 to 30 feet of line set, i’m curious, what kind of system do you have that requires 130′ of tubing under a concrete slab?

  24. Good GOD, this is not a hack, and is a very stupid idea. An EPA license to buy R22 is easily obtained if you really want to do it right. By putting propane in this system, this moron endangers his entire family, has effectively voided any possible warranty that any component of his system may have, and has potentially prevented any future REAL HVAC tech from working on his system (“Oh, you put propane in it? Yeah, I’m not touching that. Good luck. There will be a $80 service charge for me traveling to your house today”).

    Do not do this. This is not a hack, it is a free pass for “natural selection”.

    1. Jake, you don’t have a clue about what you are talking about. For starts, do you have any idea how little propane (R290) is in the system? – It is only 40% of what the, now illegal R22 is. – Do a little research before you look like a fool.

  25. Aztraph House was built > 20 years before I bought it. Long side 65′, short side 50′. Indoor HVAC in house center, outdoor unit @ far end of house. 2 rooms were added & compressor box moved about 40′ before concrete slab poured for 2 new rooms. Near as we could measure, 68′ run X 2 freon tubes = 136′. IF propane leaked under concrete slab, any flammable mixture found no under slab ignition source.
    Several years later a new system was installed in attic with new outdoor unit and 22′ tube path.

    Jake Wendy has not listed me in her web, I am still in gene pool.

  26. eric, the large line is your suction. it carries gas back to the condensing unit, the smaller line has liquid running through it, the extra refrigerant required to obtain the proper charge could get pricey. but the line itself could restrict the refrigerant and cause your pressures to be off, if they increased the size of the liquid line to compensate, that means even more refrigerant. overall not a very efficient design, i’m glad you have a new system with a shorter line set. of course the new freon flavor is r-410A, if you haven’t upgraded to it by now, you won’t have a choice as no one makes it anymore, just like r-12 back in ’94. when it’s gone, that’s it.

  27. @Anon

    No, no. I just don’t like to see “do-it-yourself” instructions posted for something that has so much potential to be dangerous, or fatal. I feel the same way about this “hack” as the one a while back where some idiot posted a “mains crossover” cable DIY, so that you could plug a generator in to a a circuit in your house, or “bypass” a blown circuit. A very, very, VERY stupid and hazardous thing to do.

    It’s my feeling that some idiot will read something like this, try it, and kill himself either by ignition of leaking propane during the charging process, or by having it leak inside their house later on. Just not a good idea at all, and this is why we use R22/etc in home A/C units.

  28. as of why they could not find a leak could be a couple things.

    1. a faulty safety release valve that is popping at a lower pressure.

    2. the r22 is not r22 at all it is r134a packaged as r22.

    i should know because the 2000 chevy geo metro that has a design flaw that allows it to lose all the charge over in a year i think due to the molecular shape and size of the r134a.

    another option would be to have all or as many connections be brazed instead of threaded compression fittings like used in cars

  29. @ejoness

    The flammability of R22 is several magnitudes lower than that of propane.

    Also, in regards to your geo metro statement: Lol @ the EPA for mandating that we use a “less harmful” refrigerant, and then that “less harmful” refrigerant ends up being infinitely more prone to leakage. I am constantly servicing and recharging R134a systems, yet I still see R12 systems come in to the shop with their factory original refrigerant charge in them. Haha.

  30. im a hvac tech there really is no problem with propane being USED but the problem with using it it will catch fire NOT BLOW UP if there is a leak and a spark.The ONLY time it would blow up if a major rupture happen and all the gas escaped all at once. also All residential units produce a spark from the contact when it closes or opens Propane has the same refrigeration quality as r12 but for a gas to be used as a refrigerant it must be NON flammable and safe to work with ….. now i have heard of many stories of guys of the olden time using propane as a r12 replacement for cars to make a buck and scam people but it will break down the compressors oil and kill the compressor but it is your shit and you find the risk ok WELL go for it … but be warned

  31. Also if you have r22 or any other refrigerant in your system still and you TOP off yours with Propane you will (prob 99% of the time) KILL THE COMPRESSOR also spend the 75 freak en dollars read the damn book and get your lic to buy the right stuff it is cheap and if you have a small leak you can top it off every yr for a long time with a jug. Now it is illegal to do so a system that leaks must be repaired by law and epa but again your shit

  32. @josh

    it maybe illegal but the laws are not enforced.

    i talked to a technician and he said that there is a 50 pound cut off allowing the average person scrapping a unit to vent it into the air.

  33. @ ejonesss
    i would love to know the EPA ordinance law and sanction code on that LOL you are alowed to vent about what your hoses use that is it also if you convict or help to convict you will be given a reward for turning people in it is like 2500$ fine and you get some of that LOL just a little FYI

  34. @josh i am talking about average people just cutting the lines and letting the gas hiss out.

    because that there is only a few oz in a window air conditioner combined with the understaffed epa’s results in them only going after the big cases consisting of emptying a large container of 50 pounds or more.

    also if you do have an old window air conditioner that you are scrapping for the metals you can safely vent by getting a piece of hose from hardware store that will fit the charge nipple and the hose acts as a muffler to cut down the high frequency hiss to a soft his that would blend into the background so the passers by dont hear the noise and become suspicious.

    from what the technician told me the laws are really meant for the manufacturers and service technicians.

    now i guess if you was a recycling or garbage station and you had many units to drain then you may have to recover the charge.

  35. when r12 was readily available, it was cheap $5 per pound or so. it’s not available anymore, and now it’s $75 to $90 a pound. r22 is now going down the same road, when i come across a clean r22 unit that’s being scrapped, i salvage whatever i can get from it.

  36. Have any of you ever seen propane burn? It burns, it doesn’t explode. Go watch mythbusters and watch them try again and again to ignite it with gun shots that go completly through the canisters, that are pressurized and sealed. Secondly, do any of you realize the conditions it takes to get propane to finally ignite? If there is too much of it like in the full canister nothing happens, there is not enough air to fuel the fire. I’m not saying this is safe but you people are treating it like hes setting the tank on fire and harvesting the explosions in paper bags. Its not the safest thing to do but its not overtly crazy.

  37. I agree with razor. It isn’t very safe, but in a pinch it would work.

    I’ve seen a firefighter put out a match in a bucket full of gasoline. Like gasoline it is the vapors that ignite not the liquid. I could see how this could be a problem in an enclosed area like say a closet. If you leave a propane torch valve open inside a house the concentration will never be high enough to get an explosion. It is simple college level general chemistry that says that.

  38. has anyone ever let the gas build up in an outdoor cooking appliance with the lid down and the burner did not light right away and then finally lit and boom it blew the lid open or off or even go boom in their face.

    also after the flood of 1996 and 2006 we had to have the hot water heater burner cleaned and one time the technician was trying to light the burner and fuel built up and flashed out.

    also while going out to a pizza shop for lunch one time they told me their oven did not light properly and flashed .

    while that is natural gas and not propane the 2 fuels are close enough they can be used interchangeably with the changing of the jets on the burner.

    mapp and Acetylene have more of a punch because if you ever seen on some of the discovery channel shows like monster garage and west coast choppers sometimes there is a pop when lighting and turning off.

    also on monster garage i believe it was Acetylene used to fill a balloon to maybe 5 inch diameter and it went off with a big bang.

  39. found more information for those of you wanting to do this, check out maxi-frig:

    i found my old MSDS page on the stuff, it’s 30-60% di methyl methane and 40-70% methylethyl metrane. the DOT classifies it as petroleum gases, liquefied, which is a form of LP gas, it is suitable as a replacement for most refrigerants out there, but it is VERY combustible (yes, i tried it, and is every bit as flammable as propane) it’s specific formula allows it to be used well with rubber hoses (which standard propane can degrade), so please, if you MUST use propane or maxi-frig, please use caution and thoroughly leak check your system.

  40. this is dumb, especially when the next certified AC/R guy comes along and tries to evac the system in to his r22/r134a bottle and then charges you to dispose of the mixed gases.. oh and btw the fine for and of the Rxxx is 10k per offense.

  41. Auto repair shops in Mexico (Tijuana) were notorious for using propane to recharge air conditioning in cars when California & other states banned older refrigerants. Dangerous situation when you have a o-ring leak and propane gas is leaking around a hot engine.

  42. Come on guys. Propane? This is not only dangerous. But Stupid and inefficient. True. Propane has the properties of a refrigerant, However. it has differing condensation and evaporation temperatures than Refrigerant, Also. in the condenser and evaporator units, There are Chemical sensitive seals that can be eaten away by the refrigerant itself, Not to mention that R22 can actually return the Compressors lubricants to the compressor rather than leaving it pool in the copper line sets like propane might. As a final note… This is A 500 dollar Fine able act. I would also like to say that, That propane, will be Spraying allover the motor windings of the compressor. one of the Major things that keeps the compressor from melting down is the Low pressure refrigerant returning to the compressor and dumping over the motor windings. This is standard in almost all compressor designs, So if those motor windings ever short and Burn out. What happens to the propane? Hmmm? It isnt as rare as you think. Since the beginning of the year, I have Assisted in Replaceing over 20 Damaged and shorted compressors from Regrigeration to heatpump, Scroll to rotor. And propane, being the highly flamable substance it is, Could Toast a house quite nicely if the compressor ever did short. Just thought you would like to know…

  43. @ JohnHVAC if propane is that bad then why does the europeans use it instead?


    1. the europeans do not have the same constitutional rights to sue if their houses burn down.

    2. like the us military feared about germany regarding helium in the hindenburg and hoarded the helium and only allowed hydrogen to be used

    maybe since cfc based freon’s can be made into (correct me if i am wrong) mustard gas and used as a chemical weapon if heated (i was told that to be careful about using a cut off wheel to cut open a compressor freshly pulled from a freshly emptied system because of remaining vapors could be lit by the sparks).

    maybe the us fears that the europeans may sell the used freon to rogue nations to make mustard gas weapons decided to only allow propane because it burns so clean that in small amounts it ban be burned indoors .

  44. @ ejonesss

    Look. I have no care at all whatsoever for the Techniques and tactics of HVAC technologies of other countries. Nor do i wish to begin Paranoid discussions that could rage for days. We all know that propane is used for cooking. Heck I made Hamburgers the other day, And I don’t know about you but I was always taught that
    1. Fuel + Oxidizer + Ignition source = Fire
    2. If said chemical reaction occurs inside of a sealed container, say like the copper lines of an air conditioner, you have a pipe bomb.
    3. If The EPA catches this. It can be a fine of over $500 for every day it is not corrected and Correct refrigerant utilized.
    4. In the US. You must Be EPA Certified. in order to be permitted to do any kind of maintenance or care to freon containing portions of devices, Even then there is Four levels of Certification; Small appliances, Residential Heat and air, Commercial Heat and air, And universal which is being Certified in all forms of HVAC Tech in the US.
    5. The EPA Can fine you for Having The refrigerant and not be Certified.
    … If all this is not Convincing enough to let a Tech do it… Here is one last reminder…
    Propane has tendency to ignite fairly easily, And there is more than likely a fair amount of Oxygen trapped in the Compressor Oil that by now has been released into the unit. In my last post I said that I have had to replace units Whose Compressors Had Been shorted out, In every case The house wasn’t Burnt Down because Modern refrigerants Do not burn easily, We replaced the refrigerant because it was contaminated with burnt oil residue, But beyond that It was repaired and running. My point is Propane+ AC Compressor + High probability of Fire +The fact that most AC units weakest point is the indoor or out door coils = High probability of A house fire.
    There Is a reason Propane isn’t used in HVAC. And If me Being EPA Certified is not a testament to my knowledge, Then I don’t know what will be good enough to convince you that this is dangerous.

    1. You really show your ignorance here. Propane is actually used and has been in refridgeration for several decades . The lp actually helps lubricate and prolong compressor life. And 101 in ac you always vacuum system down so not sure how you are going to get much oxygen in your system and definitely not enough for an explosion. You are at more risk with propane appliance in your house that usually have a 500 or 1000 gallon tank supplying the leak . Hmmm a system with a pound of lp leaking or an appliance with 400 gallons ?……..

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