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R-424A and R-434A

R-424A and R-434A

Anyone out there have any experience (good or bad) with either of these two claimed drop-in replacements for R-22, or either of the companies?

Comstar RS-44 (ASHRAE R424A)

Comstar RS-45 (ASHRAE R434A)  

Comstar’s web site at

Another site for R-434A:   

RE: R-424A and R-434A

NO -- 410a is replacing 22 in residential systems and most of the commercial systems are gravitating towards 404a for LT & MT applications.

RE: R-424A and R-434A

I would definately try these refrigerants in existing R-22 systems even though they are new.  EPA decided in that notice of acceptability that RS44, a refrigerant, is acceptable for use in new and retrofit equipment as a substitute for HCFC22 in a number of end uses for refrigeration and air conditioning. I like this refrigerant because the pressures are about the same as R-22 but the discharge temperatures are lower.  I would not use RS 45 with a cap tube system and I am not found of R-410A  

RE: R-424A and R-434A

You could check with the SCE (Southern California Edison) Refrigeration and Thermal Test Center.  They tested many of the new refrigerants before they were even given a number by ASHRAE.  I was at a meeting last week and no one mentioned this one but I will be there again next week and ask.

Go to

RE: R-424A and R-434A

I generally try to stay away from the 400 series refrigerants, but we are forced to use them since no other good alternates are available to replace R22.  R410 requires a high design working pressure to the high discharge pressure, so it it generally not suitable as a drop in.  

R507 is a good one to use if the suction pressure is not too high and you have sufficient cendensing surface.



RE: R-424A and R-434A

I wouldn't worry about 22 going away soon. Although residential equipment will be phased out in 2010, commercial production is slated until 2020.

Consider the cost of those drop-ins compared to $2.50-$3.00 lb for 22(I can buy 30 lb jugs for $75). Similarly, R12 was phased out a long time ago, but I can still get R 12 jugs for around $150 to $200.

RE: R-424A and R-434A

I meant "NO" I haven't heard any info on those drop-ins. I quickly scanned the R45 PT -- I wouldn't call that low glide.

Ask them what a 25 or 100lb tank costs -- I'm curious.

I think it's funny hearing talk about ozone depleting CFC's & HCFC's when you have hundreds of millions of gallons of Chlorine swimming pools evaporating into the atmoshere.

RE: R-424A and R-434A

I am glad that other people take the environment a little more seriously than you do.  Cost of the refrigerant is not the only issue.  Like it or not CFC's and HCFC's are depeleting the ozone layer and it has helped to reduce them.  I commend MintJulep for researching and following the spirit of the law whether he likes it or not (he doesn't say).

For someone of your qualifications which I have read so much about in your "Any P.E candidates or P.E.'s out there?" thread I would expect you to know more about the chemistry involved.  Chlorine by itself is very reactive and completely reacts before rising very far in the atmosphere.  In pools it will probably be completely reacted (almost no free chlorine) before evaporating.  Chlorine use in pools is a very minor use of chlorine in the world.  I find it ironic that the ones who know the least about the ozone depletion issue technically are the first ones to dismiss it.

The HFC's and HCFC's are very stable compounds and do not release their chlorine until the rise very high in the atmosphere where they are struck by high energy UV which breaks the bonds releasing the chlorine which then destroys the ozone.

See the book New Refrigerants for Air Conditioning and Refrigeration Systems by David Wylie and James W. Davenport if you want more information.  I recently attended a seminar with the first author and he was very informative.  It was free and it sounds as if it might help you.

RE: R-424A and R-434A

Sorry it's a McQuay document, so it gets a little bit 'gloaty' over the whole R134a vs R-123 debate that they've been pushing with Trane for the last few years.

RE: R-424A and R-434A


I take it seriously, but when you're a business owner that deals with Fortune 100 clients, you have a better understanding of dynamics involved -- I can think of 1 company that spews hundreds of tons each year

I disagree with Chlorine not contributing to Ozone depletion. The Chlorine in the pools also form Hydrochloric acids and also quickly reacts with Oxygen to deplete ground level ozone that should migrate to the atmosphere.

RE: R-424A and R-434A

Apparently you are a business owner that deals with Fortune 100 clients.  I deal with Fortune 100 clients frequently.  I don't know of any who intentionally spew hundreds of tons a year but if you do and you are a party to it, you may want to read the article at this link:

I guess that with your credentials you can just assume that you are correct and that the scientific consensus is wrong.   I won't go into the details of ground level ozone but if you know much about the chemistry of ozone, again, you would that it is very reactive (that is why it is considered a pollutant at ground level) also and will easily react before it reaches the ozone layer at a height of 15 miles.  Read about it a little more at

RE: R-424A and R-434A

Now let's not resort to name calling here folks.  I see no reason to not to continue to use R22 in existing equipment if the equipment is kept tight and leak free.  The R22 is only an issue when it is leaked.

For all of the folks pushing R-134a, it has zero ozone depletion potential, but it is reall a bad actor on the global warming we need t drop it as well?

No, the answer is to control the refrigerant and the leaks.



RE: R-424A and R-434A

Thanks Ken I needed that. If your going to disagree with someone then please try to be plesent about it and not so rightious. I dare say most of us are not impressed with someone's crendentials only what they can contribute to this forum ...plesently

RE: R-424A and R-434A

I am sorry.  I guess that I let EmeraldCoastHVACR's answers in his previous thread "Any P.E candidates or P.E.'s out there?" affect my replies here.  I should have responded in that thread if I had any issues with his posts.

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