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Old 05-27-2009, 09:56 AM   #1
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switch from R-22 to 410 A: New Lines??


I am currently looking to replace a AC unit and Airhandler and have two conflicting opinions on whether to replace the line between the two or whether they can flush the R22 line, add a vacuum to it, & purge with nitrogen before swtiching to the 410 A.

If they are to replace the line, they'll need to run it out the end gable and down along the downspout, and I'm thinking that it wouldn't look so good.

Anybody have a tie-breaker opinion on which is the right method???

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Old 05-27-2009, 10:38 AM   #2
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switch from R-22 to 410 A: New Lines??


Depending on what size lineset you currently have, R410A systems can sometimes create the break point between 3/4 and 7/8.

Can you purge an R22 line? Sure, but beyond your aesthetic reasoning, why would you? You are investing in a complete new system. Why would you leave an older possibly weak link between the two components? You also run the risk of not getting a clean purge, and then you have possibly damaged your brand new system.

If it were me, I would not consider using the old line. To me it is like going to the trouble to replace a hard to get to alternator on your car and then putting an old fan belt back on. Why would you do that?

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Old 05-27-2009, 11:04 AM   #3
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switch from R-22 to 410 A: New Lines??


There is some emerging evidence that the oils are not as incompatible as once thought. But until that is proven and reached industry acceptance, the best advice is to change out the lineset or flush.

Since there is no guarantee the flush is done right, you are taking a big risk for small reward. Discuss your concerns about visual impact with your installer. This can not be the first time they've had to deal with that issue.
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Old 05-27-2009, 12:42 PM   #4
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switch from R-22 to 410 A: New Lines??


If a new line set is ran. It can be conceiled in down spout or other casing to make it look nicer.R22 lines can be flushed and reused for R410A. Its not hard to do.Mineral oil and Poe oil have never had a problem mixing together.Its the R410A refrigerant that doesn't mix well with mineral oil.I prefer to install a new line set. But many customers prefer not ot if they don't have to.And in many condos you can't run a new line set.So if its the right size, no problem reusing it.
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Old 05-27-2009, 07:40 PM   #5
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switch from R-22 to 410 A: New Lines??


The right size issue can be VERY important. A lot of the newer units require a larger suction line than the old unit used. Needs to be upsized or you won't get proper oil return to the compressor etc and damage it.
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Old 05-27-2009, 08:09 PM   #6
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switch from R-22 to 410 A: New Lines??


I find that R410A often uses either the same size vapot line, or sometimes a smaller vapor line.

While R410A(1250FPM) on vertical risers does have a higher min vapor velocity for oil return then R22(1000FPM).

If the compressor is below the evap, it is not a concern.
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Old 05-27-2009, 10:27 PM   #7
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switch from R-22 to 410 A: New Lines??


From what I see, most if not all the 2 ton units seem to use a 3/4" suction line and 95% of the old ones used 5/8". Pressure drop is greater in the 5/8 and that can be an issue on longer runs. I liked 5/8, easier to bend by hand and a LOT less expensive to buy. 5% of our units are in attics so the evap is usually below the condensor and lift is involved. Lots of guys are still using the old 5/8 and pinching down the connection at the King valve. Used 3/4 on mine.

Last edited by yuri; 05-27-2009 at 10:31 PM.
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Old 05-28-2009, 12:00 AM   #8
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switch from R-22 to 410 A: New Lines??


On R410A. A 3/4" vapor line has a velocity of 970FPM(2 ton unit).
So 5/8"(1440FPM for 2 tons) is better for oil return if you have a vertical riser. Of any significant length.
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Old 05-28-2009, 06:14 PM   #9
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switch from R-22 to 410 A: New Lines??


I wonder why they are recommending 3/4 and have 3/4 King valves.
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Old 05-28-2009, 08:56 PM   #10
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switch from R-22 to 410 A: New Lines??


Quote:
Originally Posted by yuri View Post
I wonder why they are recommending 3/4 and have 3/4 King valves.
Cause 3/4=3/4?
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Old 05-28-2009, 10:15 PM   #11
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switch from R-22 to 410 A: New Lines??


Why are the newer 2 ton units using 3/4 instead of 5/8 like in the olden days? May have something to due with the use of scroll compressors instead of recip or to get a better SEER rating?? Just checked Davenet and the Lennox 18, 24,000 BTU use 3/4 and a 3 ton uses 7/8. My 2 ton Armstrong is 3/4. Not sure about everyone else.

Last edited by yuri; 05-28-2009 at 10:23 PM.
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Old 05-29-2009, 05:57 AM   #12
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switch from R-22 to 410 A: New Lines??


Probably has to due with what capacity rated compressor they use.

Seldom find a 24,000BTU compressor in a 2 ton condenser.
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Old 05-29-2009, 07:42 AM   #13
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switch from R-22 to 410 A: New Lines??


Thanks for the info guys. As to clarify some of the things discussed:
  • The companies that suggested running a new line would hide the line in with the downspout or in a casing. Still, there is uncertainty on how the install would look.
  • The company that suggested flushing the R22 line and reusing, did look at the size of the line before recommending the flush and reusing. They would use a vacuum on the line and a flush kit.(?)
  • If it matters, this is for the upstairs unit and the line has about almost a 30' drop in elevation.
From what I gathered on lurking on this forum for a short while that both Trane and American Standard uses the same equipment. I have 4 quotes from 4 different HVAC companies, but on the Trane and the Amer Stand. I have the same size units quoted and one suggested the new line, the other the flush. Both are within $100 of each other on a $10,000 system. It's going to be a choice betwen the two.
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Old 05-29-2009, 07:52 AM   #14
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switch from R-22 to 410 A: New Lines??


Trane and American Standard are the SAME equipment.

No difference between them, other the name, color and model number slightly changed.
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Old 05-29-2009, 08:39 AM   #15
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switch from R-22 to 410 A: New Lines??


I guess that's why the pricing is within $100. Must be the upcharge for the Nameplate??

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