Utilizing Propane as a R-22 Replacement

[steppinthrax]

I have been doing extensive research in refrigeration since my 3.5 ton Trane heat pump has sprung a leak. The leak is either somewhere in the condenser or evaporator. I've gone through the hassle of injecting UV dye through the system (one year ago) and the leak has still now shown. I have a strong suspicion the leak is on the back of the evaporator. Anyway in order to charge the system (1 to 2 lbs) the last guy charged me 250!!!! I went online to purchase R-22a (refrigerant grade propane). This time I charged it up myself last summer and it worked great. I have purchase tools that would enable to to pinpoint the leak. However that would require me to pressureize the system with Nitrogen (250 to 300 psi). This would force the leak to "show itself" (hissssss). I can also trace it better with a leak finder.

However in the meantime I want to use experiment with utilizing fuel grade propane (HD-5) to charge the system.

I'm basing this on this thread I found through google.

//ecorenovator.org/forum/geothermal-heat-pumps/2922-question-about-filtering-bbq-propane.html

(insert http before the //)

Essentially this guy was using a liquid line drier to filter the propane. One of my options was going to be charge the system up with nitrogen to find and fix the leak. Then vacuum the system down and charge with propane (by weight). I'm supposed to use 2.5 propane for every 1oz of R-22. This is a 8lb 6oz Trane system.

I was curious of the setup for filtering. I wish to use those disposable Coleman/Camping cylinders and run it through a filter. Based on the thread I posted the guy indicates he can even filter out the scenting oil?

[NiHaoMike]

Probably one of the best things to do is to freeze the cylinder to freeze out any moisture. Then draw off vapor as that's less likely to carry impurities.

You'll have to adjust the TXVs (if that's possible - you'll have to replace nonadjustable TXVs with adjustable ones) if you're running pure R290. ES-22a (often incorrectly called "R22a") is actually R433b, meaning it contains some R1270 in order to bring the PT curve up closer to R22 in A/C applications. Since you have a heat pump, you'll actually want R433a or R433c, though those are hard to find.

[steppinthrax]

I always thought propane was very similar to R22? The indoor coil uses a fixed piston (orifice). The outdoor heat-pump uses a TXV for heating. So if I simply weight in propane (as it is) that will cause problems?

[AC_Hacker]

Originally Posted by steppinthrax

I always thought propane was very similar to R22? The indoor coil uses a fixed piston (orifice). The outdoor heat-pump uses a TXV for heating. So if I simply weight in propane (as it is) that will cause problems?

This issue has been extensively discussed on EcoRenovator. I suggest that you use the "Google Custom Search" that is at the top of each and every page. Every detail, every angle will show up for you there.

The short answer is that Propane is flammable, whereas Freon is not. So, if you decide to use Propane, you will be accepting responsibility for the consequences those hazards carry.

As to functionality, yes it will work without significant modification to your system. In fact, it will most likely give you greater performance per dollar.

As was indicated above, modifications can bring marginal improves in efficiency.

'Weighing in' propane will not work, as Propane and R-22 have different densities.

Use 'the Google' to see how other folks have done it.

Then there is the legality issue. We wouldn't encourage anyone to break any laws.

Sincerely,

-AC_Hacker

[jeff5may]

You have your masses messed up... Propane is much less dense than R22. You will weigh in roughly 40% propane from empty based on your name plate value. For an 130 ounce r22 system, you will weigh in around 3 pounds to start out. This is from a deep vacuum. It is better to run a retrofit setup a little undercharged, because R290 has more heat capacity than R22. A cooler evaporator means more heat gathered per cfm, and the R290 can absorb it.

Before you pull a deep vacuum on your system, swap out the filter dryer with a brand spanking new one. Grab another for the charging hose to catch the stink oil on the way in. As AC Hacker stated, beware of the danger involved and observe general safety rules. Always have a method for disconnecting power and a fire extinguisher close at hand. Use the right tools for the job and quality instruments for best chance of success. Consider the consequences of what you are planning on doing before you do it, and if you're not sure what will happen, stop and ask questions.

To find those hard, slow leaks, here's a tip: Go to the dollar store and buy a jug of Scooby Doo bubble blowing juice. If it isn't thick enough for you, nukeit for a minute or two and mix up some laundry soap powder in it. Don't tell anybody, but the tire shops use this on the tires so they don't have to dunk them in a tub.

Good luck, and let us know how you're doing.

[AC_Hacker]

Originally Posted by jeff5may

Always have a method for disconnecting power and a fire extinguisher close at hand.

These are all good precautions, and I would add an additional precaution, which is that Propane is heavier than air, and will quickly sink to the ground if you are outside, and to the floor if you are inside.

Do not do any Propane hacking inside, especially in a basement.

Propane can be ignited by pilot-lights, relays, DC motors, etc.

Go outside. Set up a fan to blow any propane away from you.

ALWAYS WEAR A FACE SHIELD.

-AC

[steppinthrax]

Originally Posted by AC_Hacker

These are all good precautions, and I would add an additional precaution, which is that Propane is heavier than air, and will quickly sink to the ground if you are outside, and to the floor if you are inside.

Do not do any Propane hacking inside, especially in a basement.

Propane can be ignited by pilot-lights, relays, DC motors, etc.

Go outside. Set up a fan to blow any propane away from you.

ALWAYS WEAR A FACE SHIELD.

-AC

Thanks,

Yes, this is a HP no gas furnace exist. I feel the risk of flammability is real low. since I have mostly R-22a (r-290) in the system anyway and it's been working good. I'm going to try to scooby doo bubble juice.

I've did research in this area and apparently if there is a leak in the system it wouldn't cause an issue, it would have to leak out all at once and come in direct contact with a flame. It would also have to be the right concentration. At worse you would see a big fireball....

[AC_Hacker]

Originally Posted by steppinthrax

...I've did research in this area and apparently if there is a leak in the system it wouldn't cause an issue, it would have to leak out all at once and come in direct contact with a flame. It would also have to be the right concentration. At worse you would see a big fireball....

This is not completely correct...

Propane would not have to leak out all at once for a hazard to exist. The significant issue is that if there occurs a propane and air mixture that reached a critical ignition level, it could ignite explosively, if exposed to open flame OR spark... propane camp stoves have pizo spark igniters on them, so spark from relays or any motor that used brushes against a rotating copper rotor COULD do it.

Sailboat owners that use propane cook tops are well aware of the hazards. SEE_THIS_PAGE.

A 3.5 Ton unit heat pump could hold a significant amount of Propane.

> At worse you would see a big fireball...

This is a joke, right?

* * *

From what you have said so far, you have a 3.5 Ton system that has a leak, and you do not know where the leak is... right?

And you want to change your system that you know is leaking, to use propane, a gas that is extremely flammable, as the refrigerant?

And you think that, "At worse you would see a big fireball"?

(* you need to consider the possibility that a 'big fireball'
might be the last thing you would ever see *)

From what you have said, I don't think that you fully understand the hazardous condition you are proposing. In other words I don't think that you have sufficient respect for this process.

I would strongly advise you against proceeding with your project.

Sincerely,

-AC_Hacker

[jeff5may]

Ok, I believe I read your initial post wrong. What you are saying here is your system has a slow leak and was initially charged with R-22. A tech came out and determined (one way or another) that your system was low on refrigerant and topped up your system with R-22 but did not (or could not) repair the leak. Since then (to save money), you have been topping up your system with ES-22a using an unknown (to me) method. It is showing signs of being low on charge again, and you want to add a third gas into your already mixed up system? To save even more money, I assume?

There are a few things wrong here. The main thing is that you will never get the system working properly with an unknown mixture of who knows how much refrigerant in the circuit. Before doing anything more, you need to learn how to charge your system by superheat and/or subcooling measurements. To do this, a digital thermometer or two and a quality refrigerant gauge set are needed. Once acquired, they can only do their jobs taking measurements. You must learn how to interpret what you see to formulate a course of action. Just adding "some" refrigerant can make things worse in a hurry, as over or under charging a system puts different components at risk, even when the system acts like it is doing its job. This is one reason techs charge a lot for the service they provide.

My question is this: if you find a teensy little leak somewhere, how do you plan on fixing it? Most of the time, the flare fittings and service valves and rotten o-rings in split systems end up being the culprit. Very seldom, an actual pipe or hard plumbing part develops a pinhole. Regardless of the source, you can't just blob some glue on it or tighten up a fitting. You will most likely end up needing to dismantle something and drain the charge from the system in order to do a repair. Once the repair is done, the system will need to be purged of gas and a deep vacuum pulled. Then a pressure test with nitrogen will follow, then a vacuum, then nitrogen, then a vacuum. If a leak is detected, you must start all over.

This is a very precise process. There are a great many variables at play, as well as a handful of things that can go wrong and produce the same effects and/or symptoms. To affect a lasting repair, all of the doubt must be eliminated. Considering the state of your heat pump, no one can tell you exactly what to do without actually being there and doing the work. I would start out assuming everything that can go wrong is awry and start there.

This is the wrong time of the year to learn how to fix your heat pump. If it was mine, I might just call out a tech and have them verify the charge for 200 bucks. Then in spring or summer, I might revisit the issue when I didn't absolutely need it to work. But then again, you're not me.

[steppinthrax]

Originally Posted by jeff5may

Ok, I believe I read your initial post wrong. What you are saying here is your system has a slow leak and was initially charged with R-22. A tech came out and determined (one way or another) that your system was low on refrigerant and topped up your system with R-22 but did not (or could not) repair the leak. Since then (to save money), you have been topping up your system with ES-22a using an unknown (to me) method. It is showing signs of being low on charge again, and you want to add a third gas into your already mixed up system? To save even more money, I assume?

There are a few things wrong here. The main thing is that you will never get the system working properly with an unknown mixture of who knows how much refrigerant in the circuit. Before doing anything more, you need to learn how to charge your system by superheat and/or subcooling measurements. To do this, a digital thermometer or two and a quality refrigerant gauge set are needed. Once acquired, they can only do their jobs taking measurements. You must learn how to interpret what you see to formulate a course of action. Just adding "some" refrigerant can make things worse in a hurry, as over or under charging a system puts different components at risk, even when the system acts like it is doing its job. This is one reason techs charge a lot for the service they provide.

My question is this: if you find a teensy little leak somewhere, how do you plan on fixing it? Most of the time, the flare fittings and service valves and rotten o-rings in split systems end up being the culprit. Very seldom, an actual pipe or hard plumbing part develops a pinhole. Regardless of the source, you can't just blob some glue on it or tighten up a fitting. You will most likely end up needing to dismantle something and drain the charge from the system in order to do a repair. Once the repair is done, the system will need to be purged of gas and a deep vacuum pulled. Then a pressure test with nitrogen will follow, then a vacuum, then nitrogen, then a vacuum. If a leak is detected, you must start all over.

This is a very precise process. There are a great many variables at play, as well as a handful of things that can go wrong and produce the same effects and/or symptoms. To affect a lasting repair, all of the doubt must be eliminated. Considering the state of your heat pump, no one can tell you exactly what to do without actually being there and doing the work. I would start out assuming everything that can go wrong is awry and start there.

This is the wrong time of the year to learn how to fix your heat pump. If it was mine, I might just call out a tech and have them verify the charge for 200 bucks. Then in spring or summer, I might revisit the issue when I didn't absolutely need it to work. But then again, you're not me.

Thanks for the information.

Yes, I understand that since I've mixed refrigerants I can never get a accurate value. I simply did this to get by for the time being until I can do a complete change-out.

I have done plenty of reading on calculating superheat/subcooling. However, I can't use these methods during the winter since the temp has to be at least 60 degrees and it has to be running in cooling mode. Based on my reading it seems charging by weight is a lot better. (1) Recover all of the charge, (2) Weight in the charge based on the nameplate sticker (3) Add .6 oz per foot of line-set after 25 feet. I was reading that the charge you get in this situation tends to be the most accurate and you can check your subcooling values based on this when the summer rolls around.

I have exhausted time looking for the leak. I purchased two leak detectors to look for it and I have used soap bubbles everywhere. I found the possibly (from talking to a tech) of a leak occurring on the service valves. I removed both caps and placed Teflon tape around the threads. I'm not sure if this is the ultimate source of the leak, however since I've done this and charged the system again my Delta T during the Winter (35 to 40) has been around 21 - 22 degrees F. I've in general been able to get 91 to 92 degrees out the supply plenum.

When I called two techs out to the system almost both told me that the leak is likely coming from the evaporator. They simply said this because the evaporator looked corroded. However, neither could demonstrate the leak nor could they find it with their leak detectors.

Last year I injected 1oz of UV tracer dye into the system. The system had been running since and I've used a UV light everywhere and could never find the leak.

Based on the last response from the person regarding the dangers of using Propane. Honesty, I'm a little warry of using this, but I'm thinking it may not be worth it.

I'm finding 10 lbs of R22 one ebay for actually not that expensive (150 or so). I have several tools I've gathered over the months (2 nitrogen tanks, 2 nitrogen regulators, aceteleye tank with turbotorch, refrigerant scale, K-type clamp thermometer). I'm going to purchase the H10G leak detector (ONE OF THE MOST SENSITIVE LEAK DETECTORS). I will pressurize the system with dry nitrogen to design pressure, then I will try to detect the leak.

If that dosen't work I will most likley change out the whole system. I'm looking at a 3.5ton goodman with air handler and 35' of lineset for around 2K. It's 3 SEER higher than what I have and I believe I have all the tools necessary to install. It's a R-410 system. Precharged and I will simply need to add about 6 oz of extra r-410 to top it off.