I am playing with R290 "BBQ style"

ok. Please don't flame me. My test system is one that I own and it's a ancient POS. I don't mind blowing up a compressor or trashing it.

The system is from the 1980's and used capillary tubes for regulation and is 2 ton. The condenser is way way under sized and placed on top of the unit so Hail could tear the hell out of it.

I have replaced the horizontal A coil with a 2-3 ton York unit and setup a R22 TXV. I just saw a cool 2 ton R410a condenser on craigs list for a easy $150 that looks new. The 410a system has a way over sized condenser for high efficiency. I may put that one in ..

My plan is to mate this to the A coil, Install a dryer/filter and let her rip. Will perform the usual sub cooling charge and tweak the TXV after it has settled in.

I have been using BBQ gas for a while now and I must say it works great! I use driers because I don't know how pure it is but I am very impressed so far. Got a adapter on E-bay so I could hook my gauges to it.

Thoughts?

Thoughts are what I'm sure you would expect.
Have you considered electrical side being safe around flammable gas.
You might trash a compressor or be making a bomb.
How much refrigerant,is in it?

I have to use TXV valves I tweak that were intended for R22. They work well because of a very similar thermal curve. in capillary systems it's a disaster. R290 is more fluid so the orifice is different.

I have never really weighed a charge. I just make sure I have enough for the system to operate properly. I would say it takes less than R22 to properly charge. It works great but a TXV (that requires adjustment) is a must. I have not experimented with piston sizes. I am sure that would work if you had a jar of them to play with.

As far as the "bomb" comment. I am not mixing oxygen in with the r290. It's just pure R290 so with out an oxidizer it is not a bomb! If you have a leak fast enough to cause a fire hazard you made a serious error even charging the system! I guess in a earth quake if pipes were ripped apart it could be a hazard. Like the gas lines that go to your place. But it would be nothing compared to the rest of the disaster including the "gas lines" that were damaged in a quake.

The biggest risk with r290 is it not being properly marked and a technician coming on site would not know what he is dealing with. They could start a fire not realizing it was flammable. I make sure my systems are very well marked!

There are r22 replacements out there all ready that are very flammable. It's all a big game and lots of money is involved for refrigerant manufacturers. But physics are physics and I am not a lemming.

I have been using R290 (C3H8 = Propane) in an old Prestcold K100/0017 unit with no mods whatsoever since 2001 with no problems, except that now I have electrical problems and I am in the process of replacing the start caps and relay and the run caps, none of which is due to using R290, obviously!

The unit is clearly marked in several places "Warning: re-gassed with R290" ;)

You are quite right when you say "lots of money is involved for refrigerant manufacturers" and "physics are physics".

I have used R-290 a la bbq bottle for personal equipment with no problems, I run it through a scrubber, basically a system with allot of filters and plenty of oil to absorb any garbage in it.

Hydrocarbons make good refrigerants imo.

Oh just knock the oil up to 200sus or so, and make sure to use a crank case heater as it loves to hang out in oil!

You won't get good results using an r410a compressor though. They have a significantly smaller displacement than an r22 unit, so you'll move less heat and use less electricity. The lower load on the motor will give you a crap power factor too. Other than that, it'll work... Sorta. That's no reflection on r290, just a mismatch between compressor spec and desired refrigerant.