Refrigerant Lines Underground

Issue

Installing refrigerant lines underground

Resolution

Trane compressors are only warrantied for manufacturer's defects.  With underground piping it is impossible to determine if a compressor failure is a manufacturer's defect.  For this reason, Trane must assume it is an installation error.  Trane will not authorize replacement compressors or repairs.  Trane will also not accept responsibility for any other problems caused by underground lines. This document is NOT an authorization for installation of underground lines.  No additional warranty is expressed or implied.  

Avoid putting refrigerant lines underground. Refrigerant condensation or installation debris inside the line, abrasion/corrosion, and limited service access can quickly impair reliability, and may result in compressor failures. Reasons to avoid underground lines are:

• Potential warranty limitations
• Limited service access to the lines after they are installed
• Refrigerant condensation inside the line when the system is off, and subsequent refrigerant flood back to the compressor
• Lack of installation cleanliness
• Vibration- and corrosion-related leaks
• Moisture in the subsoil and groundwater flow resulting in undesired heat transfer
• Expansion and contraction of pipe leading to compromised lines
• Loss of insulation effectiveness due to moisture, and groundwater flow
• Damage from burrowing or nesting wildlife, and their acidic wastes
• Other unintended consequences

In the event of a refrigeration or compressor issue, the cost to expose, inspect, and repair underground lines is prohibitive.  Often the contractor will try to "encourage" the manufacturer to participate in a solution that does not involve exposing the lines.  However, as the problem is not a manufacturers defect, this prolongs the customers frustration, expense, and difficulties.  For this reason refrigerant lines should be installed above ground. 

If the engineer/architect/owner determines that project needs outweigh the risks, the lines should be routed in a chase below grade or a chilled-water system should be used.  As each project is different, and the architect and engineer have final authority, they should determine an appropriate chase design.  It should be also noted that installing in a chase does not absolve the design team of associated risks.

If there are truly no other alternatives, and the owner, engineer, and contractor are willing to accept the potential risks, the following suggestions are offered only as good faith suggestions with no warranty expressed or implied. 

1. Completely manufacture the entire line set (from point ends above grade) above ground on supports
2. Cap off the tube ends
3. Properly and safely vacuum and pressure test the lines for leaks
4. Insulate the lines with closed cell insulation

5. For longer lines allow for expansion and contraction in packed or settled earth. 
6. Hard case the pipe/insulation (it must be totally vapor proof)
7. Place the line and hard case, in the trench and cover it.  (Some installers will install an extra "safety or redundant set" of pipe and cap/charge with nitrogen in case the first pipe fails.)
8. Safely release the pressure and uncap the line and braze it to the above-ground line set using a nitrogen sweep
9. Complete normal installation procedure

For more information:
Trane Air Conditioning Clinic, "Refrigeration System Components," TRG-TRC005-EN. (Trane personnel can access this manual from eLibrary)

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.