VRF Refrigerant Piping Thermal Expansion

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VRF Refrigerant Piping Expansion Loops - Pipe Leaks
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VRF Piping Hangers and Expansion Loops

When hanging or fastening VRF copper refrigerant piping that involves long runs, then some form of considerations needs to be made for expansion due to temperature differences.

If no allowances are made for expansion in the ACR copper piping then leaks are possibly to occur at some point because of the stress exerted on “Y”-Branches, joints, equipment connections or 90 degree elbows.

Thermal Expansion

The thermal expansion of piping or materials of various composition expand and contract with a change in temperature. Therefore, we find expansion joints in concrete, or we use bi-metals in thermostats. The ability of metals and materials to expand and contract has been used to accomplish great inventions, but it can also cause havoc if not designed into your VRF system.

When running long lengths of ACR copper refrigerant piping you want to allow for the pipe to grow as the temperature increases. Your copper piping can expand up to 4” in length depending on the temperature and length of run. it’s more likely that you’ll experience from 1/2” to 2” of expansion in refrigerant piping systems. Allowing the copper piping to move is critical when you have long runs.

VRF Refrigerant Copper Piping Hangers

It’s like a pool cue when playing billiards, you allow the cue to slide through your fingers without a firm grip so you can move it back and forth to hit the pool ball.  The same needs to happen with your VRF refrigerant piping, it needs to move through the hanger holding it to compensate for the expansion. The hanger should hold the refrigerant piping firmly, but should allow for it to move slightly to avoid rupture of a joint. You can use some form of expansion loop.

VRF Refrigerant System Piping Expansion Loop
VRF Refrigerant Piping Expansion Loop

Expansion Loops and U Bends

You can also use some sort of thermal expansion device to compensate for the growth in length. You can accomplish the required thermal expansion compensation by fabricating a small shaped “U” bend or “Loop” in your long run of VRF Refrigerant piping.

VRF Refrigerant System Piping Expansion U-Bend
VRF ACR Copper Refrigerant Expansion U-Bend

How have you corrected for thermal expansion or have you ever experienced a pipe leak due to the lack of an expansion loop or “U” bend?

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