Refrigerant line set (pipework) can have a significant impact on heat pump performance. A properly sized and installed line set gives a safe, efficient and reliable installation necessary for the heat pump system to perform properly. All refrigerant line set installations should be performed in accordance with the manufacturer recommendations. Follow manufacturer's instruction for pipe sizes, minimum and maximum line set lengths, and height changes, with consideration to the following:

• Follow section 5.12, 6.2 and other relevant sections of CSA C273.5-11.
• Design pipelines for the shortest runs and minimum number of joints and bends to limit internal friction and reduce risk of leaks.
• Insulation must cover the entire line set length to avoid condensation and decreased efficiency. In addition, both pipes (i.e. supply and return) should be insulated separately to minimize heat transfer between them.
• Glue insulation joints to prevent condensation from dripping inside space.
• Protect the outdoor line set from insulation damage with rigid line hide and building code-approved line set protection.
• Protect any remaining exposed line set with UV-resistant tape or other mechanical protection.
• Protect line set penetration through the building enclosure with rodent-proof insulation (e.g. with PVC sleeve and cap drilled to the size of the refrigerant lines, metal-wool stuffing, or similar).
• Correctly seal all penetrations through the shell of the home with insulating sealant/spray foam. As necessary, use gasket material to properly seal all penetrations.
• Return any insulation disturbed by installed line set to original (or better) condition.
• Create new flare fittings (where used), using flaring tool and measurement gauge appropriate to the applicable refrigerant (e.g. old R22 flaring tools should not be used for R410A refrigerant systems) and in accordance with manufacturer's instructions.
• Apply refrigerant oil to the end of each flare.
• Purge brazed connections with dry nitrogen while brazing to prevent oxidization.
• Slope pipes towards the compressor to allow any oil that gets into the pipes to drain back to the compressor sump (some compressor oil will likely get into the pipeline in any system, and if it remains there it will de-rate the system's pressure and hence its efficiency).
• Make tubing connections using gasketed press/crimp designed for the refrigerant and tubing type (e.g. Sporlan Zoom Lock^®, Vulkan LokRing^®).
• Use factory-supplied flare adapters where necessary to connect to equipment and avoid field-fabricated tubing flares.

Follow the steps given below to perform good-quality refrigerant line set work:

1. Select suitable pipes and joints (i.e. pipes must be rated for the refrigerant pressure being used in the system).
2. Ensure pipes are clean and moisture-free.
3. Make bends properly and use proper bending tools to prevent kinking.
4. Create flared joints properly.
5. Ensure pipework is properly-supported or clipped to prevent sagging, excessive movement, or an unsightly installation.
6. Insulate refrigerant pipework.
7. Position and connect the condensate drainage pipe properly.

Do Not:

• Reuse manufacturer provided tubing flares and fittings.
• Use an old R22 flaring tool for R410A refrigerant systems (i.e. R410A flaring tools create a larger flare wall to withstand the higher refrigerant pressures of R410A systems).
• Use line sets used for R22 for R410A systems without flushing them with an agent like RX11.
• Use a saw blade to cut the pipe.
• Mix polyolester oil and mineral-based oil.
• Use leak lock or PTFE tape, as these are not plumbing joints.
• Cross thread the fittings, as you may damage them.