1.3.1 — Pipe and Equipment Insulation
Supports and insulation are part of system performance: insulation controls heat gain and heat loss along refrigerant lines and prevents surface condensation when properly sealed. An insulation system that is correctly sized, correctly installed, and fully sealed at all joints and penetrations is essential for system efficiency and for preventing moisture damage to building structure and equipment.
Insulation Types Used in HVAC/R
Closed-Cell Elastomeric Foam
The standard insulation for refrigerant suction lines and chilled water piping. Brands include Armaflex, Rubatex, and Aeroflex. Closed-cell structure provides a built-in vapour retarder — critical for below-ambient service where condensation on the pipe surface would otherwise cause moisture damage and ice formation. Available in tubes and sheets; thickness selected based on pipe size, service temperature, and condensation risk.
Fibreglass Pipe Insulation
Rigid preformed sections with an outer vapour-barrier jacket (ASJ — all-service jacket). Used for hot-water heating pipes, domestic hot water, and some chilled water systems. Fibreglass does not provide a vapour retarder on its own; the jacket must be kept intact and all seams taped. Not recommended for surfaces that regularly operate below ambient temperature without additional vapour barrier treatment.
Rigid Mineral Wool / Phenolic
High-temperature rigid pipe insulation for steam, boiler flue piping, and high-temperature hot-water systems. Mineral wool sections are secured with banding and coated or jacketed. Phenolic foam offers very low thermal conductivity and is used for district cooling and chilled water systems. Both products are more labour-intensive to install than elastomeric foam.
Insulation Installation Requirements
Correct Installation for Condensation Control
- Insulate before hanging: slide elastomeric tube insulation onto the pipe before making brazed or soldered joints where possible; installing insulation after joints are made requires splitting and gluing at each fitting, which introduces potential vapour leak points
- Seal all joints and butt ends: every longitudinal seam, butt joint, and fitting cutout must be glued and pressed fully closed; a single unsealed seam allows warm humid air to reach the cold pipe surface, condensation forms inside the insulation, and the insulation system fails
- Maintain insulation continuity at hangers: use insulated pipe hangers (pre-insulated or with insulation insert) for below-ambient piping; a bare metal hanger touching a cold pipe creates a thermal short-circuit and a condensation point at the hanger contact area
- Size correctly: insulation wall thickness must meet the requirements of the system design and any applicable energy code (Ontario Building Code, ASHRAE 90.1); undersized insulation on suction lines allows condensation even if all seams are sealed
- Protect outdoor insulation: elastomeric foam degrades in UV; outdoor line sets must be covered with UV-resistant jacketing (aluminium, PVC, or UV-rated foam coating) to maintain long-term vapour barrier integrity
Bare fittings, service valves, and flanged connections on below-ambient piping are common sources of condensation drips and moisture damage. Pre-formed fitting covers, sheet foam cut-and-glued around complex shapes, and valve insulation kits are available for all common fitting types. Leaving these components uninsulated significantly reduces the performance of an otherwise correctly installed insulation system.