replacement a/c line question

[94yj]

i am having a new system 16 seer 410 system installed and they are wanting to use the existing refrigerant lines and just flush the lines out is that normal and should i have any or should i go ahead and have them replaced?problems also the lines are in a house that it 35 years old and as far as i can tell no leaks as i never had the add r22 all help and opinions are greatly appreciated

 

[JackDiddly]

Flushing linesets has become a common practice especially in homes where it would be a larger construction project to replace.

 

[PelicanPines]

I had my system replaced as you are. I didn't like the existing line hidden in the walls... I had them run a new line up the side of the house buried in a downspout specifically designed to hide it.

That said... the answer is YES it's common to flush and reuse if it doesn't leak.

 

[justinjoyal]

If the lines can be replaced without excessive trouble, have it done.

 

[samss]

Are the copper lines the correct size for the new system? If so, at least replace the lineset insulation.

 

[acmikee]

yes they can be flushed. look at the old lines are they brazed or soldered if they are not brazed then replace them. look for signs of corrosion, bends or kinks, or wear.
are they soft or hard lines. if hard leave them if soft look at the old install and them decide. if they replace them will they be using soft or hard my guess is soft copper

 

[LS6 Tommy]

Flushing linesets has become a common practice especially in homes where it would be a larger construction project to replace.

It's common place (by hacks), but not accepted by any manufacturer and the line size has to be increased if the run is more than 25'.

Tommy

 

[brewchief]

It's common place (by hacks), but not accepted by any manufacturer and the line size has to be increased if the run is more than 25'.



Tommy

Lennox lists the proper flushing procedure in the installation instructions and has for the last 20 or so years. Our field technical rep has also gone over it multiple times.

Lineset size is dictated by the equipment, some needs larger lines and some will not, some of the new variable refrigerant condensers require different size piping in the vertical then the horizontal if the lineset is over a certain length.

The manufacturer is normally pretty helpful when it comes to lineset sizing.

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[BD1]

Verify with manufacturers warranty. Years ago some manufacturers would not accept flushing.
IF they reuse ask about warranty on old piping. My guess is they won't warranty it.
Maybe ask what new line warranty would be.


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[LS6 Tommy]

Lennox lists the proper flushing procedure in the installation instructions and has for the last 20 or so years. Our field technical rep has also gone over it multiple times.

Yes, but Lennox's procedure uses R22 to flush. I should have specified I meant using chemical flush concoctions, which void all manufacturer warranties.

Tommy

 

[metlmunchr]

Using the existing line set does not void the warranty. If anyone doubts that, feel free to check the current installation instructions for retrofitting current equipment on a R22 system as published by Carrier, Trane, York, or Goodman. Those brands and their associated sub-brands make up the majority of equipment installed today.

All say it is preferable to change the lines, but none have it as a condition of warranty. Nor do any of them prohibit the use of a chemical flush as a condition of warranty.

Verifying proper line sizing is required, but, once again, the majority of existing lines will be the correct size for an equivalent capacity system assuming the lines were sized properly when the original installation was done.

IMO, dealing with any indication of a current or previous burnout is about 20X as critical as fretting over an ounce of residual oil in the lines. Anytime a burnout is indicated, every effort should be made to replace the lines. And if that's cost prohibitive, then my own approach would be to create my own flush via pumping about a hundred bucks worth of liquid R123 thru the lines rather than relying on a $75 spray bomb of chemical flush.

 

[rlitman]

yes they can be flushed. look at the old lines are they brazed or soldered if they are not brazed then replace them. look for signs of corrosion, bends or kinks, or wear.
are they soft or hard lines. if hard leave them if soft look at the old install and them decide. if they replace them will they be using soft or hard my guess is soft copper

Instructions for new R410a installs require purging lines with nitrogen before brazing. I've seen examples where skipping this voids your warranty. That's something that was NEVER done with old linesets, so how do we go on to say that it is safe to re-use old linesets?

Also, copper work hardens with vibration, eventually leading to cracking. That's usually only an issue near the compressor, but if the lineset wasn't secured well, it could give you a shortened lifetime at other places too.

And how much money are we talking about to replace a lineset? It can't be that much in the whole job.

...IMO, dealing with any indication of a current or previous burnout is about 20X as critical as fretting over an ounce of residual oil in the lines. Anytime a burnout is indicated, every effort should be made to replace the lines. And if that's cost prohibitive, then my own approach would be to create my own flush via pumping about a hundred bucks worth of liquid R123 thru the lines rather than relying on a $75 spray bomb of chemical flush.

I see your point, but unless there's some special reason why replacing the lineset will be prohibitively expensive, how much does that R123 flush plus labor really cost in relation to replacement?

 

[94yj]

thanks for the help it is greatly appreciated the company went ahead and replaced the lineset to new lineset as the old one was to small for the h/p system

 

[brewchief]

Instructions for new R410a installs require purging lines with nitrogen before brazing. I've seen examples where skipping this voids your warranty. That's something that was NEVER done with old linesets, so how do we go on to say that it is safe to re-use old linesets?



Also, copper work hardens with vibration, eventually leading to cracking. That's usually only an issue near the compressor, but if the lineset wasn't secured well, it could give you a shortened lifetime at other places too.



And how much money are we talking about to replace a lineset? It can't be that much in the whole job.







I see your point, but unless there's some special reason why replacing the lineset will be prohibitively expensive, how much does that R123 flush plus labor really cost in relation to replacement?

The only thing purging with nitrogen while brazing does is reduce the amount of oxides formed inside the lines, as soon as the unit is turned on the refrigerant and oil will scrub it out of the lines and either leave it in the filter/dryer or it will end up in the oil and probably settle out in the compressor.

Manufacturers may not recommend using a chemical flush because of the potential for it to get left in the system if there are spots that can trap oil and any flush mixed with it.

I've seen some manufacturers say it's ok to reuse a lineset and not flush it, blow out any oil you can with nitrogen and not worry about it.

We use RX-11, it's pretty easy to tell if there is any flush left in the lineset as it won't pull a good vacuum, if you use plenty of nitrogen to push the flush through and plenty after it's not an issue.

Most of the time when we flush a lineset it's because you would have to tear apart drywall ceilings or walls to replace it, the flush isn't exactly cheap and it adds some time so if replacement is practical it gets replaced.

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[metlmunchr]

Most of the time when we flush a lineset it's because you would have to tear apart drywall ceilings or walls to replace it, the flush isn't exactly cheap and it adds some time so if replacement is practical it gets replaced.

Good example of this..... A friend has a 3200 sq ft brick 2 story on a sloping lot with a walk out basement. Recently replaced the 21 yr old system for the upper floor due to recurrent leaks in evaporator. 80% gas furnace, slab coil, and 2.5 ton R22 straight cooling condensing unit. Condensing unit located at basement level. Replaced with 95% furnace, coil, and 16 seer 410A cond unit.

The ref lines were in the exterior wall of the house. To replace would require cutting sheet rock on the upper floor as well as removing kitchen cabinets, tile backsplash, and sheetrock on the first floor.

So, in this case, replacement of the lines would've cost at least twice, and likely 3X as much as the total equipment cost. Line sizing was good. Cut them loose at both ends. Blew out with nitrogen. Capped and pressure tested both lines at 500 psi for 24 hours. Good to go.

There are hundreds, if not thousands, of houses in any decent size town where similar conditions exist and where line replacement would be similarly cost prohibitive.

 

[LS6 Tommy]

Instructions for new R410a installs require purging lines with nitrogen before brazing. I've seen examples where skipping this voids your warranty. That's something that was NEVER done with old linesets, so how do we go on to say that it is safe to re-use old linesets?

I'm on board with what you're saying, but I was taught to purge when I was an apprentice in the 80's. "Never" is a little strong...

Tommy

 

[BD1]

I'm on board with what you're saying, but I was taught to purge when I was an apprentice in the 80's. "Never" is a little strong...



Tommy

I too used a nitrogen purge on all copper refrigeration lines. Amazing difference using a purge. My apprenticeship started 1970.


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[American Locomotive]

A lot of guys don't purge. Probably the same guys that think it's normal for a condensing units to only last 8-10 years before needing replacement.

Most of the commercial guys that serviced our equipment at my old job always purged while brazing.

 

[rlitman]

Well, I was always under the impression that inert gas purging before brazing was a new practice, but I'll stand corrected.

 

[TRWham]

I'm on board with what you're saying, but I was taught to purge when I was an apprentice in the 80's. "Never" is a little strong...

Tommy

I too used a nitrogen purge on all copper refrigeration lines. Amazing difference using a purge. My apprenticeship started 1970.


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A lot of guys don't purge. Probably the same guys that think it's normal for a condensing units to only last 8-10 years before needing replacement.

Most of the commercial guys that serviced our equipment at my old job always purged while brazing.

Well, I was always under the impression that inert gas purging before brazing was a new practice, but I'll stand corrected.

The point here is that purging should always have been done when brazing, but is not strictly necessary when soldering. Because of the higher pressures of 410A, lines should now be brazed, thus purging is required. In refrigeration we always brazed copper with higher silver content filler, so purging is nothing new. Every supermarket I ever worked with had specifications for field connections that included N2 purging and listed the required filler material for various types of connections.