When joining copper tubing together or to a system component in lieu of a brazed connection, the use of a mechanical connection is not new to our industry. Flare connections have been used for years, but they we’re limited to use on only soft (annealed) copper. When properly prepared and assembled, they did provide a leak-free connection without heating the tubing. But over time and perhaps due to slight imperfections in the assembly, the connection could loosen and cause refrigerant to leak out. Because of this, manufacturers and technicians opted more often to use a brazed connection.
Today, the use of pressed connections for joining both hard drawn and soft copper tubing is gaining popularity for many reasons. It is definitely a time saver; a pressed fitting can be assembled more quickly than a traditional brazed connection. This can significantly reduce the installation time of a system. A pressed connection also does not require heating of the tubing, which is another big advantage. This not only leads to a safer installation, but it also prevents the possibility of the copper oxides from entering the system if a nitrogen purge is not used.
However, there are some disadvantages to the use of pressed fittings, and one of the biggest is cost. The tool requires a sizable investment, and the fittings are pricier than the traditional sweat fittings. Another potential disadvantage is the location of the connection. The crimping tool may not fit into the location to allow the jaws to fit properly. Also, it is not possible to reuse the fitting — basically, it is one and done. So if a mistake is made, it is necessary to replace the fitting and most likely a section of tubing.
There is also another less discussed disadvantage to a pressed connection. This is more on the servicing side of replacing components and tubing. When using a pressed connection, the fitting must match the tube end exactly. Servicing systems can be a time-sensitive job, meaning the system needs to be up and running quickly. If relying solely on a pressed fitting and the right size is not available, the job cannot be completed. With brazing, it is possible to reshape the end of the tubing to transition from one pipe size to another. When necessary, I have used a pinch connection to get the tubing connected and the system up and running. This would be not possible with a pressed connection.
I did recently see another option on the market. It is a fitting that can be used on a refrigeration system that works just like a SharkBite® connection commonly used on plumbing applications. It has all the advantages of the pressed fitting without the high tool cost, and the tubing can be removed and the fitting reused if needed. Not sure how long this type of fitting has been around, but I have never seen it until recently advertised at a local wholesaler. Right after that, I was servicing an older walk-in cooler with a pretty long line set and there was a major section of tubing that used what looked like a similar push-to-connect fitting. The walk-in cooler had been in service for many years, so I was not sure if this fitting was originally designed for a refrigeration system or if it was misused by the installing contractor.
When it comes to connecting copper tubing, there are definitely some options to consider. They all have their own advantages and disadvantages. It will be up to technicians to decide which method best suits their needs — or they may opt to use them all, deciding which one works best on a particular installation or repair.