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What is YOUR policy for topping off a 410a system after the leak is fixed? A few years ago we were told to reclaim it all and recharge if the standing pressure didn't meet the PT chart within one degree. Any leak always showed a 8 degree difference from what it should be. Now they say it's perfectly fine to leave what's left of the old in and simply add what's needed. That just sticks in my craw something fierce since it's not a proper blend anymore. Do you reclaim it all or just refill?
 

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Depends where I find the leak.
I generally determine how low it is on charge by its operating pressures and saturation temps before I look for a leak.

Can't go by standing pressure with R410A to well when the air handler is in a cool basement, or in a 130° attic.

I top them off. And find no noticeable loss in capacity.
And that is with doing a capacity test at the air handler/furnace. Checking both sensible and latent capacity.
 

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The manufacturers of R410A have tested it. And removed up to 50% of the charge, and then topped off the charge, repeated. And had no noticeable lost of performance.

Lennox use to tell you you can top off the charge in vapor on a new system.

I have topped off quiet a few R410A systems. And when we had out 3 days of above normal temps last year. None of those systems had a problem keeping up.

The fractionation worry is a left over myth from the early days of R410A, before most people had taken any training on it.

If you reread about it. It is very very hard to get it to fractionate.

Recently, on another forum. A guy posted that they were taught that they can only use 80% of the R410A in a jug. The last 20% won't be a proper mix.

It will be years before all the myths are finally laid to rest.

Like the one that says you can't remove moisture from POE oil. So you hav to dump all the oil in the compressor. Not true.
Or the one that says POE and mineral oil don't mix. Not true.
 

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410a is a binary near azeotrope, however unlike other binarys and near azeotropes it's fractionation and temp glide is so marginal that it is negligable and it should be treated as a single component refrig. like r22
 

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R410a does fractionate or you could charge it in gas form from the jug.
R-410A is a near azeotropic refrigerant mixture with a negligible temperature glide. There are no concerns about fractionalization should refrigerant loss occur, so R-410A can be added without any concern. It is highly recommended that R-410A be charged as a liquid only, not gas.

Source: http://www.epatest.com/R410A/manual/manual.jsp#faq
 

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I would agree with beenthere. It keeps the customer happy and in my experience doesn't cause any long term problems.
 

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The piping might handle the extra pressure but don't take the risk of using old line set with a new unit, the oil on 410 units is like a sponge to moisture and you will shorten the life of the new unit, also make sure you use a vacuum pump and micron gage to check for moisture and leaks.
No problem with reusing the old line set either.

You blow it out with nitrogen first. To remove excess mineral oil from the lines.

You check for leaks using nitrogen to do a pressure test. You shouldn't be using vacuum to check for leaks. Since if you have one. You would be pulling moisture into the system/line set/coil.
 
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