Insco Distributing, Inc. R-410A UPDATE SEPTEMBER 15,

Since the introduction of R-410A, new unprecedented issues have come to light. This new mixture of R-410A and POE oils is acting as a solvent. As a result, the released contamination is re-depositing in metering devices. We know that the hygroscopic nature of the POE oil requires more attention to detail. Preventing moisture from entering the system must be a TOP PRIORITY! The two most frequent questions we receive are: Can we use the existing lines? Can we just change the TXV on the existing R-22 Coil? Before we answer… 2

DID YOU KNOW? While a proper flushing practice may be effective in clearing some residual oil, the flushing agent or loosened residue that may be left in the system can be more of a problem? Sampled and dissected TXV’s and reversing valves returned to the factory indicate a considerably higher failure rate on systems where the existing line-set has been used? Many of these devices have been found to have a sticky substance which appears to be made up from a brownish residue re-deposited from the existing lines? 3

DID YOU KNOW? Vacuum pumps do not “suck” moisture out of a system? The pumps reduce the atmospheric pressure and boil moisture changing liquid to vapor. The vapor then crystallizes. This is why the best method for removing moisture is triple evacuation. No amount of evacuation will remove any soot, acid, oil, or other contaminants from the system? Acid neutralizing products will NOT solve an acid problem? Acid and base react to form the basic elements of salt and water. The salt that forms is a corrosive metallic salt sludge, which remains in the system to corrode components and potentially clog TXV’s. An acid removing drier is the best solution for acid? 4

Can we use the existing lines?Page 1/3 Only as an absolute last resort AND if you follow these guidelines, and the “BEST PRACTICES” listed for R-410A: 1.Is the current line-set the proper size for the new equipment? If yes, then they must be properly cleaned and flushed. (See Armstrong’s flushing instructions). If not, you MUST use a new line-set. 2. What is the operating history of all previous systems? If it had a burn-out or often ran low on refrigerant, then it is likely the system has acid or other contaminants! DO NOT USE the existing line-set!! 3. If you CAN use the existing lines, then on cooling only systems install the filter-drier near the indoor coil to ensure there is no residue getting into the metering device. 5

Can we use the existing lines?Page 2/3 4. If you CAN use the existing lines, then on heat pump systems install one filter-drier near the indoor coil AND a second filter-drier near the outdoor unit in the liquid line to ensure there is no residue getting into the metering devices. This concept may seem to conflict our “conventional wisdom”, but the POE oil is bringing new challenges to our industry. 5. If you run new lines on heat pump systems, then the drier should be installed nearest the metering device being used first. Ex. Installation in May will run on the cooling mode, then install drier near the indoor coil. 6

Can we use the existing lines?Page 3/3 6. Consider this: Our industry is supposed to use ACR Nitrogenized copper that has had high pressure standards (600+ PSIG), but a lot of “plumber’s” copper and fittings have been used because it’s cheaper. Our industry is supposed to braze, not solder our connections. Brazing ensures the same working pressure as the copper tube, but I know that suction lines have been connected with solder because “suction pressures are low”. 7. Who said that lines are supposed to last forever??? Many line-sets are 30 and 40 years old! Do you really want to trust them to the new higher pressures of R-410A? 7

Can we just change the TXV on the existing R-22 Coil? Page 1/2 1.The easy answer is NO! The R-22 coils are rated with UL and AHRI listed at 250 lbs. of pressure. 2. If you want a YES answer, then look carefully at this: a)Some manufacturers got their coils listed for the higher pressure of R-410A at an early date. b)Effective with date code F/M2608, all residential indoor evaporator coils from Ruud (“N” coils, Multiflex, RCQC, and RCQD) have been tested to 550psi. The 550psi test is the current standard applied to all coils used in R-410A applications. Having all coils tested at this higher pressure standard, regardless of their intended application, is in anticipation of providing field replacement Thermal Expansion Valve Kits for all models for R-22 and R-410A refrigerants.continued 8

Can we just change the TXV on the existing R-22 Coil? Page 2/2 c)Since the higher ratings started with Ruud in 2008 and other manufacturer’s much earlier, now the challenge is to ensure that a conversion from R-22 to R-410A is still an approved match for the new condensing unit. 3.Now that you have a YES answer, the next challenges are all 7 items included in the question of existing lines with these extra notes: a)On item 3 a suction line filter drier should be used to catch any contaminants that might have entered the evaporator coil during the R-22 operation. b)On items 4 & 5 consider that if the system is first run on the heat mode, the drier at the outdoor unit will catch anything that is released. However if it is first run on cooling, a suction line drier should be used for clean-up and then removed prior to running on heat mode. 9

Best Practices For Handling R-410A Page 1/2 1.TOP PRIORITY - The top priority is yours and your personnel’s SAFETY! 2.Next priority is preventing moisture from entering the system. 3. Never leave the refrigerant system open to the atmosphere for more than 15 minutes. 4.Use oversized driers for better moisture removal every time you install or open a system. 5.Always cut-out filter driers using a tubing cutter. Never un-sweat or saw-cut the drier out. 6.During service, measure temperature drop across the filter-drier. Limit the delta-T to 2 degrees. 7.Use sight glass to monitor moisture with the green dot. 10

Best Practices For Handling R-410A Page 2/2 8. Always use new properly sized ACR copper and ACR wrot copper fittings, and braze all connections. 9.Use a nitrogen purge when brazing. 10.Use a wet rag or heat block when brazing near TXV’s, Reversing valves, or Service valves. 11.Pressure test lines for leaks at 600 psi. 12.Triple evacuate with final at 500 Microns and hold for 5 to 6 minutes. 13.When ready to charge the system, open the suction service valve first. 14.If additional refrigerant is needed, charge with liquid ! 15.Do not mix POE oil with any other oil! Use sight glass to monitor moisture with the green dot. 11.Never leave the refrigerant system open to the atmosphere for more than 15 minutes. 12.Do not mix POE oil with any other oil! 11

12 Page 1/4 For a better copy go to: Product Technical Support Line Set Flushing

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