Refrigeration Line Set Life Expectancy

Refrigeration Line Set Life Expectancy

Dave Borowski
Contributing Writer
Direct Energy

Line Sets?   Really? — yes really.

Let’s be realistic………..    All things deteriorate, even common concrete block only matures to peak hardness in year 40-50 then begins decomposing.  Copper was chosen as the line set material primarily for its dense characteristic where the molecules of refrigerant would not permeate it.  And all things considered – uninterrupted (no joints), non-contaminated (external oxidation & internal oxidation) only leave the copper lines sets exposed to extremes of vibration, thermal & pressure related expansion and velocity friction.   Contamination seems to be the wild card – systems in beach environments are clearly at a disadvantage, with line set life possibly being as low as 5- 10 Yrs.   With the absence of contamination concerns, the general accepted life expectancy of line sets is 25 Yrs., outside of that number, you’re on borrowed time.

Make yourself an expert, be street smart – know when to recommend new:

1. The most critical element is quality of the installation.

• Soft Copper:  The care in handling the lines is critical – if lines were ever partially bent & then straighten back out, there will be small to moderate stress fatigue on the walls of the copper.   This will over the years reduce service life (leaks).  I’ve personally seen 10+ yr. old lines that were severely kinked, then straightened in the field leak from friction at the previously kinked area.   The use of soft copper can also totally avoid buried or concealed joints as lines sets are available in 100’ & 150’ continuous rolls.

• Hard Copper:  Overall the best choice of products and of course will not have succumbed to bending issues, however hard copper mandates the use of brazed 90 degree and couplings vs. swedge where soft copper can be gently bent to totally avoid 90 degree elbows & swedged joints reducing the qty. of welded connections substantially.  Overall – hard copper has the best professional look and offers a clean finished product accepting pipe supports etc. without sags (oil accumulation) in the line sets.  There have been documented occasions over the years from time to time of poor wall thickness or even fragile pipe as offshore recycled or contaminated copper was employed – clearly reducing life expectancy out of our control.

• Type of copper:  With some frequency the wrong copper is installed that has manifest itself with premature line set failures.  K-L-M copper is engineered for plumbing, ACR is engineered for refrigeration.  K-L-M does not have consistent wall thickness and waxes are employed in the manufacturing process that leads to systems contamination where ACR has a consistent wall thickness & is prepped as dehydrated (and sealed).    In some cases the manufactures stamped / inked ID remains on the outside of the piping, also ACR is always measured OD, so as a cross check the type of copper can usually be ascertained.

• Quality / Craftsmanship of brazing joints – both material & craftsmanship.  15{938cd9e8dae860e800efc538277d4f7684e6f6981618ba70d1c34357a53c2e1f} silver rod is ideal where 5{938cd9e8dae860e800efc538277d4f7684e6f6981618ba70d1c34357a53c2e1f} is more commonly engaged due to initial cost.  The 15{938cd9e8dae860e800efc538277d4f7684e6f6981618ba70d1c34357a53c2e1f} rod is more forgiving and flows better into brazed joints – however IF the joints were all sanded clean and prepped and the joint itself was not overheated, the strength of the joint is not diminished by the use of 5{938cd9e8dae860e800efc538277d4f7684e6f6981618ba70d1c34357a53c2e1f}

Before we leave “craftsmanship” – let’s address sanitation.  Refrigeration principles haven’t changed – ever.  In fact with the new refrigerants and their oils being hydroscopic – you could argue the bar has been raised.  So a few items come into play:

i.     NITROGEN.  ALL brazing requires nitrogen sweeping at very low pressure, just enough to displace the oxygen and the burnt remains the heating process creates in the tubing.  This is the same crusty smudge on the outside of copper following brazing.  While not impacting the life expectancy of the copper – that contamination has to end up somewhere.

ii.     OIL   – no one understands this concern better than our commercial techs out there.  All those hulking remains of discarded oil cans on the roof…. Where is the oil at?   While not impacting the life expectancy of the copper – that contamination has to end up somewhere.   Not to mention the loss of heat transfer once the evaporator is coated internally.

iii.     DYES / ADDITIVES – Sorry guys, I know this will be met with some disagreement – but nothing except refrigerant oil & refrigerant belongs in a system.   While not impacting the life expectancy of the copper – that contamination has to end up somewhere.

iv.     DRIERS  What were you thinking?   Refrigeration principles have not changed – in fact:  with consideration to hydroscopic oils, extreme sensitivities of the newer TXVs that may have 100’s of set points modulating electronically, higher head pressures that induce acid formation and OEM failures of reversing valves where they have actually internally RUSTED, moisture control is more critical than ever.   Here’s a HEADS up you may have never seen coming:  While a DRIER will always stop rocks & chunks of random solder via the screens, the dehydration and acid absorbing characteristic is CONSUMED in the 1st FIVE hours of run time … after that it’s virtually a door stop.   I shouldn’t have to say more here – you know what the right thing to do is.  While not impacting the life expectancy of the copper – that contamination has to end up somewhere. 

• Supports & Isolation of the lines (to code) will have prevented vibration and oxidation from contact w/ steel or concrete.  Underground lines change all the rules, as any sleeve short of continuous and glued PVC with terminations well above grade will be saturated w/ ground water.  Wet lines, considerably deteriorate systems performance.  Buried lines overall in my experience have a base line life expectancy of 10-15 Yrs., even less if the ground contains high concentrations of phosphate (fertilizer from previous farm land / golf courses) or construction debris.

• Commissioning / first start is likely the most important day to reflect on.  In hind sight, there is no way to validate this effort, IF the line sets were pressurized and proven not to have minute leaks then dehydrated properly the likelihood of workmanship issues will have been reduced to near zero.  Certainly – any go forward activity would include this validation plus the addition of liq.& suction driers, I also strongly suggest:

Locating liquid drier @ the AH (where it belongs)
Adding a moisture indicating sight glass
Wire-brushing and painting the suction drier after installation.

2. Experience ratio / accessibility of the lines sets are the next consideration.

• History of line set failures, regardless of age – with consideration to the rapidly rising cost of refrigerant and the maximized application of labor;  if line set failures are the experience – all line sets should be replaced

• Accessibility; with consideration to manpower, cranes, roofers, job staging, drywall penetrations, permitting – there is an economy of scale that reduces cost per line set and can factor into preserving the life expectancy of the existing equipment if all the lines in a chase are replaced at the same time.  At minimum – with consideration to the likelihood of future line set replacements, every effort should be made to install permanent access panels or oversized pipe shields (for future line sets) as required.

• Location:  Buried line set failures are common, regardless of the protection provided – water saturation is an issue with various degrees of oxidation.   Note – with the greatest frequency the buried section of the line sets is replaced leaving the vertical risers in place.

3. Summary Notes for consideration.

• Industry supporting data, it seem the variables are too deep to get a consensus on life expectancy of line sets.  We have to use common sense.

• http://www.prolineab.com/life_span_pipes.aspx

• Industry wide, it was anticipated that the new non fluorocarbon refrigerants would mandate replacement of the lines sets.   We’ve learned with exception to possible system capacity loss (wrong size copper) the only issue is the oil incompatibility form the old to the new Freon.   There are commercial sweep kits that will remove oil from the line sets.

• OEM Warranty consideration sooner or later comes into play.   Manufacturers as sensitive (and always looking to obfuscate liability) to the impact the improper or contaminated line sets have on the life expectancy of their new compressors.  Any deviation from the OEM specs and standards of care for our industry (see Trane manual) will impact future life expectancy of products.   As such – and with consideration the EPA mandates have terminated (most) all R22 products in favor of R410A I would STRONGLY suggest a very compelling reason to upgrade line sets during any renovation.

• Professionalism and to address LIABILITY.   Customers are relying on YOU to be an expert – know the facts, be that expert, offer sage advice.

• Condensation lines; as a side bar note it’s worth recognition that the age of the line set and the condensate lines are identical.   Condensate lines suffer most of the same trauma refrigerant lines do plus severe contamination.   I would strongly recommend:

The same time line for life expectancy

Any Time a drain has failed more than TWICE in a season (this allows for a great line evacuation) – it MUST be replaced or a condensate pump installed.