How to Avoid Water Damage and Mold Issues on VRF Projects

One of the most critical (and sometimes overlooked) aspects to a complete and thorough VRF installation is the layout, preparation, installation, and subsequent insulation refrigerant piping. Three keys to a proper install are:

Proper brazing techniques (adequate flow of nitrogen, full penetration of the brazing filler, etc)
Accounting for expansion and contraction of the pipe (100’ of tubing can expand and contract up to 2”)
Pressure & leak testing each portion of piping

After properly installing all that refrigerant piping, the costly mistake we want to avoid is water infiltrating the insulation and building envelope. Three reasons for this are:

Moisture will reduce the thermal efficiency of the system
Moisture could eventually corrode the piping, fittings, and valves
Moisture can lead to the dirty ‘M’ word no one likes talking about, mold. We insulate our refrigerant piping for two main reasons.

#1 – Maintain system capacity and efficiency by reducing the number of BTUs that are lost to the atmosphere.

#2 – The second (and probably more important) reason is to maintain a solid vapor barrier for our refrigerant piping. This prevents condensation on the piping or insulation and will help prevent moisture accumulating where it shouldn’t and potentially propagating mold growth.

The list below is not all encompassing but should limit your liability on an install. Best piping practices would dictate:

Use at minimum the VRF manufacturer recommended thickness
Use EPDM insulation
- It is UV rated for any portion exposed on a roof
- It is rated for the high line temps that VRF experiences
Do not compress or stretch the insulation as it will damage the cellar structure of the insulation
- At hangers/supports use a rigid insulation insert with ‘C’ clamp and Unistrut
- Use saddles and shields where appropriate
- Don’t use zip ties to attach control wiring to the piping
If using split insulation, make sure the seams & joints are properly sealed with adhesive
Apply contact cement every 12’ – 15’ to adhere the insulation directly to the copper piping to form a vapor dam. This will prevent the migration of moisture or water between the tube and insulation in case of any breach of the insulation vapor barrier
Be sure to seal the insulation at the top of all vertical piping runs
Insulate all branch fittings, ball valves, branch box, fan coil, and condenser piping connections Please let me know what I’m missing from the list and I’ll get it added!

Please let me know what I’m missing from the list and I’ll get it added!

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Travis Hunt

Senior Sales Engineer at cfm Distributors, Inc.

Travis loves to get out the office and onto a job-site to assist with load calcs, equipment selection, or coil replacements. And yes, his favorite equipment to select is chillers.

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