R407c

[dunny123]

Is it true that if you have a leak on a R407c unit,you have to reclaim the gas and put a fresh charge in?I was under the impression that 407 is not diffrent to any r400 gases.Ie charge as a liquid,due to it been a blend.But some one told me today that you cannot add gas to a 407 system,is this true?
{after you have fixed the leak of cause}.

[tarcau mihai]

There is another thread with this subject.On cruise ships we use to charge over not to recover and recharge..
Regards Mihai

[Haden4ever]

your about right, the glide on 407 makes it unwise to top up, i can't remember the amount you can lose before it's a full change, but if it's a good leak then i'd charge with virgin as the performance drops off dramatically, i'm sure someone can give you figures if you need them

[littleyapper]

i was told that if the leak is from the high side then you can but if it's a low side leak then reclaim and recharge... reason being vapour no body knows what leaks out and what percentage of each leaks

[Gary]

I have heard this theory many times over the years, and I don't doubt that a leak in just the right place at just the right time could drain off one of the component refrigerants... but what effect would topping up the charge have on the actual operation of the system?

I seriously doubt that the effect on the system's operation would be noticeable and have yet to see any evidence to the contrary. Surely someone somewhere has actually tested this.

[acnerd]

www.centrogalileo.it/nuovaPA/.../RIVOIRA%20inglese.doc

This document is interesting. To paraphrase what it says, you CAN top up R407c on non-critically charged systems (ie. chillers), but split a/c systems are critically charged, so you would have to start again.

[acnerd]

Sorry, just tried the link and it's broken .... I'm rubbish on pc's. :mad:

I tried to attach the document, but it exceeds the 100kb limit.

[Gary]

If I am in fact wrong and zeotropes must be regassed rather than topped up, then where is the sense in using them? As a prime example R404A (zeotrope) is almost identical in composition and characteristics to R507 (azeoptrope). R404A can fractionate, while R507 cannot. This alone seems to make R507 the superior refrigerant.

[slingblade]

Difficult to tell what Gary has told you as he is on my ignore list. R407c is a blend, however i have recharged systems that have lost 70% charge as a vapour with no problems afterwards. I just use it like 22 with no problems. ( dont mix it with 22 though, that may be bad)

[Peter_1]

Gary, there was (is?) on the website of Rhodia (France biggest refrigerant manufacturer) a technical paper saying that you always can top off R407c systems.
Practical tests over years showed now difference.
They shouldn't say this officially if they weren't 100% sure.

[Eeram]

Like Gary said, how does the blend know what part must leak out and what part must stay.

What sometimes happens is that with a leak and maybe running your suction in a vacuum, you could add non condensebles and that could change the state and behaviour of the refrigerant, which are mistakingly blamed on the refrigerant.

Never had the problem with blends, ****tails, whatever, as long as the system is not 90% empty. It is then a good idea to reclaim the charge, change oil and driers, vacuum and recharge.