[sdf]

need some help I'm a heating & air guy who hasn't done to much of any refrigeration. I have a R-12 system if I evacuate can I recharge with 134a or any other replacement refrigerant for R-12 so long as I put in the right oil or is it not possible to put 134a into a R-12 compressor & evaporator. please explain drop in replacement & replacement refrigerants & whether or not you can use these refrigerants in a compressor not specifically made for them

 

[d_griff]

need some help I'm a heating & air guy who hasn't done to much of any refrigeration. I have a R-12 system if I evacuate can I recharge with 134a or any other replacement refrigerant for R-12 so long as I put in the right oil or is it not possible to put 134a into a R-12 compressor & evaporator. please explain drop in replacement & replacement refrigerants & whether or not you can use these refrigerants in a compressor not specifically made for them

R 414-b but if im not mistaken only charge to 80% of the old r-12 charge,it is a direct drop in,i only dabble in it as well but ive done it that way,im sure you'll hear more about diff. types like 404

 

[Special-K]

Give us some more info. Cooler or freezer. Walk in...reach in...ice machine...what? Expansion valve or cap tube?

 

[sdf]

cooler with cap tube

 

[kitchenfixer]

The 414b, as mentioned by the other "dabbler", is probably a good choice. It's pretty well readily available at local parts stores and such if you need a very small quantity, and I have had success with it (even as a "top-off"). Believe it goes by the trade name "hot shot" or "freeze 12". I'm pretty picky (read "anal") about most things and this has been a good enough product that I have purchased a 30lb'r. Good Luck!

 

[Wheelbaron]

Again I say try MP 39 it works better than R 134-A, although it dose have a higher head pressure. Very forgiving in a dirty or burnt system, when used with the correct drier/filter

 

[Special-K]

My top choices would be MP-39 or R-409. On a close coupled system like that you wouldn't have to change the oil. Evacuate, change the drier, weigh in 80-90% of the R-12 charge and tweak from there. get the box to temp and make sure the superheat is 20-40* at the compressor.

 

[james264]

K-fridge put me on to the mp-39 a couple of weeks ago. I gave it a try the other day great stuff!!!!!!!!!!

 

[ReferTroop]

R-414B HotShot vote...

My preferance would be R-414B HotShot, suction pressure runs lower, head pressure definatly runs lower than MP-39. Besides it will mix with any oil, and these things on here that I've heard about the 1.5% of it being iso-butane and explosive is Bull squat. It does hae 1.5% iso-butane but the rest of it is basically what used to be used in fire extingushers meaning 98.5% fire extingusher if it leaks off. (halide fire suppresion system in a MRI computer room for example).

JS

 

[Special-K]

Sometimes we place too much importance on head pressure. If you guys take some before and after baseline data you'll likely find that when properly charged the blends that run higher head won't increase the current draw of the system over what it was with R-12. In my experience the difference in head pressure with the blends is minimal if you charge the system right. Most of the complaints with the blends in medium temp systems are due to improper charging or a fault with the equipment. I have used several of the R-12 replacement blends and they all worked fairly well in medium temp applications. They have their differences; some run a bit higher head, some have more capacity, some are more compatible with mineral oil, some require greater TXV adjustment...but they all worked. I don't want to get into bashing but HotShot was my least favorite of these. Though it may be one of the easier refrigerants to retrofit, I was not impressed by it's performance in terms of capacity. MP-39 and R-409 get top marks there. MP-39 performs a bit better, but R-409 is more tolerant of mineral oil in remote systems. MP-66 is the clear champ at low temp applications.

As for the hydrocarbon (iso-butane, etc) issue...some of the blends use a small amount of hydrocarbons to improve oil return. Hydrocarbons make an excellent refrigerant and they have great miscibility with conventional oils. Only problem is...they are flammable. Now, the blends sold in the US only have a very small percentage of hydrocarbons. These are typically not enough to be explosive or even flammable without help, but some will burn if subjected to an open flame is memory serves me correctly. Typically, this is not a big deal. However there may be some applications where they could be dangerous.

Back when R-12 was first phased out, there were some blends brought quickly to market (mostly for auto A/C retrofit) that were extremely flammable and even explosive. Hopefully the government put a stop to all of those.

 

[dngtig]

Use any of the refrigerants noted above but don't use r134a or you will be in for more than you bargained for.

 

[270wsm]

K_Fridge

I used to use MP39 and it was good. But I have been using Hothot for 2 years now and it seems to work just as good as MP39 and I dont have to worry about the oil. I have noticed Hotshot seems to work better in hot kitchens where condensers are in high ambient conditions. Hotshot does have a higher Critical temperature(if that makes any difference). And its capacity is 8% more than R-12. Overall i have been pleased with its performance in everything I have used it in from small reach-ins to walk-ins(medium temp of course).

As far as low tem R-12 replacement, MP-66 is by far the Champ.

And since we are on the subject of drop in blends, 422A is the best choice I have found for 502 replacement. Even have a couple racks running this stuff with no problems.

 

[Special-K]

I used to use MP39 and it was good. But I have been using Hothot for 2 years now and it seems to work just as good as MP39 and I dont have to worry about the oil. I have noticed Hotshot seems to work better in hot kitchens where condensers are in high ambient conditions. Hotshot does have a higher Critical temperature(if that makes any difference). And its capacity is 8% more than R-12. Overall i have been pleased with its performance in everything I have used it in from small reach-ins to walk-ins(medium temp of course).

As far as low temp R-12 replacement, MP-66 is by far the Champ.

And since we are on the subject of drop in blends, 422A is the best choice I have found for 502 replacement. Even have a couple racks running this stuff with no problems.

A lot of people use Hotshot and swear by it, if you have confidence and experience in it then you're ahead of the game. Like most other issues, an experienced tech and and good retrofit is often more important than the color of the jug.

 

[rayr]

There is only ONE drop in refrigerant for R-12 and that is R-12. Any other replacement refrigerant requires some scrutiny at the very least.