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Old 11-15-14, 06:11 PM   #261
mejunkhound
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mercaptan is a methanol with the O replaced by S.

The filter/dryer in a hvac system removes the mercaptan.

FWIW, the mercaptan will also absorb and acid in the system and be taken up on the dessicant in the filter/dryer.

So, beneficial, but does load up the filter/dryer faster.

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Old 11-16-14, 10:18 AM   #262
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I bought 2 x 41 cubic inch LIQUID LINE FILTER DRIER's
1st to filter the propane through when charging. 2nd stays in system between condenser & TXV & also acts as a receiver.
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Old 11-16-14, 10:28 AM   #263
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Jeff5May, your post quoting from that study:

"...the high solubility of mineral oils in propane could represent a problem, especially for applications such as heat pumps displaying high suction pressures... the experimental results reported in the present work can therefore be explained by means of the strong influence that the propane solubility could have on the sealing effect of the lubricant between piston and cylinder... the solubility is shown to strongly decrease by increasing the superheating; as a consequence, the viscosity of the oil strongly increases with superheating until reaching a maximum at around 30-40K superheating... the suction superheat would have a positive influence on the volumetric efficiency."

Also in that study MO ISO32 viscosity is only 58% (22/38) of POE ISO32 viscosity at same testing conditions.

So why use MO?
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Old 11-16-14, 11:29 AM   #264
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Default I heart mineral oil

I like mineral oil for a whole lot of reasons.

1. It is in the scavenged R22 compressors and heat exchangers I use in my monsters. No compatibility issues there.

2. It isn't a lover of moisture. The ester and glycol and AB oils absorb moisture and don't let go of it. Once your synthetic nu-oil system sees moisture of any sort, it's time for an oil change (no fun). With my mineral oil system, if something bad happens (leaks suck), I can add back any lost oil (if necessary), pull a deep vacuum for a while, and nearly all the water will be drawn out of the oil. After a double or triple purge/evacuation run, I'm good to recharge with assurance the oil in the system isn't tainted. At least not with moisture.

3. It is pretty well inert. If you have a burnout event, it doesn't break down into gloop, moisture and sludge that clog up everything. POE oil also shares this property, unless there is moisture present anywhere. If i was lubricating a jet engine, I would use POE because that's what it was made for. Of course, at jet engine temperatures, all the water boils right out.

4. It is compatible with pretty much all commonly used (and most uncommon) refrigerants. The other oils may react with whatever is (or was) in your system unless it is spotless on the inside. If I was producing virgin units from brand new parts, this wouldn't be a problem. A quickie blow-out with system flush or brake parts cleaner (non-chlorine) and inert gas, and I'm ready for that new (to me) compressor to braze in. You never know what might have been run through those used units in the past.

5. The viscosity index issue with R22 in cold weather is offset by the solubility of propane. When it gets really cold outside, R22 doesn't thin the mineral oil like R290, so you have that "cold cranking" issue like with your car. With propane, it dissolves in the oil like CO2 in soda pop, so when you start up cold, the oil is thin with dissolved liquid propane. The otherwise normally thick oil flows like water and foams up like soda pop, coating all the parts that lie in its path with a layer of oil as the propane boils out. Once the stuff gets to a pressure where the propane has very much superheat, it separates from the oil, causing the oil to thicken to its "normal" value.

In large, industrial/commercial type systems, some of these reasons don't hold up. Such as in the paper BBP cited, they use hermetic piston or screw compressors instead of rotary or scroll compressors. Most of the oil doesn't circulate through the whole system like in smaller systems like I work with. They have things like oil separators and dedicated oil pumps, which don't work correctly when the oil foams up. In such systems, the other types of oil work better to their reduced miscibility with refrigerant gases.

Last edited by jeff5may; 11-16-14 at 01:44 PM..
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Old 10-29-15, 04:08 AM   #265
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Quote:
Originally Posted by buffalobillpatrick View Post
This was posted on a Pro HVAC site:
"Even with that as I stated if you just recharge your old R22 system properly with R290 you will gain an over all efficiency increase of about 20% to 30%. "
Hello, I have made my first attempt in DIY heatpumps with R-290 (topic #1767) :
http://ecorenovator.org/forum/geothe...festo-177.html

I had a small discussion about it (topics #1771 > #1774) with jeff5may and I'd also like to hear your comments and "capitalize" on your experience on R-290.

Here are a few questions:

- Do I need a bigger evaporator or a bigger TXV orifice, since the system had a bigger cooling capacity with R-22 than with R-290?

- What would be the optimum SubCool (for charging) and SuperHeat (for TXV regulation) for a R-290 retrofit with a suction line HX.

Thanks in advance!
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Old 10-29-15, 07:32 AM   #266
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Tried R290 in a ac only unit and in a minisplit both worked great. Since the minisplit was a rental I purged the unit after verifying it worked and switched back to R410a prior to installing.
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Old 07-28-16, 10:19 AM   #267
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About 10 years ago I was in Belize working on my drinking problem on a small island "Caye Caulker" and I saw this guy charging a AC system with a BBQ gas propane of bottle. I asked him... Your freon comes in propane bottles? He laughed and said it is propane. He said everyone uses it and has been using it for years. So I started digging around on the web and discovered that most of Asia and about all of central America use the stuff.

I have been using "BBQ" gas for about three years now. Playing with my own systems. I have been using it in R22 systems. I have yet to have a failure on any of these systems other than the usual "A coil leaks, caps, contactor and blower / fan motor problems". All the A coil leaks were there in the first place and thats why they ended up with R290. The stuff works great. You can retrofit R410 systems with the stuff. "change the metering system to a R22" It is oil compatible with anything! I do recommend adding driers because I don't know just how pure "Rhino Gas" is.

You can purchase the Propane BBQ gas bottle adapter for your gauge set on ebay for about $15.00

Not only is it Dirt cheep, Does not damage the environment and it actually has lower pressures and works better than R22. It is almost a drop in replacement. My TXV systems hardly require any adjustment. Most of the time I don't even need to adjust anything. Sub cooling is good!

As far as blowing up a house... Well some of the R22 replacements are HFC's anyway "probably mostly propane / butane etc" and will do the same thing. I have never seen a evaporator explode and dump all it's gas. A condenser maybe when the fan eats a hole.

I know there are lots of by the book players out there. I am not one of them. I like to play and learn. I have been playing with this stuff and I LOVE it! I sold off my extra R22 because I have no need for it! Keep in mind I don't work on other people's systems. Only my own. "I have dozens of them". In a short time we will probably see a acceptance of the stuff. The most efficient heat pumps over seas already use it!
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Old 07-28-16, 11:46 AM   #268
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Here is the one BIG problem with propane - it is more dense than air . . .

In a leaky system (and they all leak sooner or later), if installed in a basement, propane will "spill out" over the floor and sit there. The vapor pressure is not huge so it will remain there for a long time (hours to days).

One spark in the vicinity (static, light switch, burner turning on) and it will explode.

I have absolutely no problem with propane in a car AC system as it will spill out (if there is a leak) into a non-enclosed space.

Years ago, a neighbor had a propane leak on his 250 gallon tank. It was located in his backyard and the downhill path of the propane "spill" was obvious. It then filled a small depression in his yard almost like an ethereal pond. It was like a mirage shimmering there and was quite obvious. He almost brought out a household "box" fan (open motor) to blow it away and I told him NO!

We called the fire department and - believe it or not - they use high pressure water sprays to disperse a standing propane "island" (that is what they call a propane spill). I asked them what they do in a house (with a basement) when this occurs and they laughed. "We don't get those calls - the home insurance company does as the home is often blown up".

If they can, they use a fan with an enclosed motor and they push air into the home (to disperse propane) and they never suck it out.

Natural gas (methane) does not have this higher density issue and that causes other problems.

Lastly, 100% propane cannot blow up - it needs to properly mix with air (oxygen) to do so. But even a poor mixture (too rich or too lean) can cause extreme and exciting effects.

I suspect AC agrees . . . .


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Old 07-28-16, 01:56 PM   #269
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Quote:
Originally Posted by Thepprof View Post
Tried R290 in a ac only unit and in a minisplit both worked great. Since the minisplit was a rental I purged the unit after verifying it worked and switched back to R410a prior to installing.
It's rare to hear of this kind of hack!
What brand and model was the mini-split? Was it also a cool-only?

How much 290 charge did you use compared to the 410a charge?

How was the BTU vs watts-used performance of the 290 compared to 410a?

Thanks,
Rich
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Old 07-28-16, 02:09 PM   #270
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I second what Steve Hull posted.. After reading about propane sinking into the nearest hole,
I decided to move all my plumbing propane out to the garage.. (No basement)..
After a few years out there, there isn't much rust on the bottles..
My basement is a bit damp, and has radon gas, but it's propane free!


Thinking about sump pumps right now.. Wondering if they all have explosive-poof switches?
I remember a time about 35 years ago, when I used a standard micro switch to make
my own float switch, to power a submersible pump..
(The basement was flooding at 2AM and I needed sleep)..
Thank the PTB there wasn't a propane leak! Because I used that hack,
until the pump died about 5 years later..

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