Umar Shadab
MEP Engineer | Consultant
Dubai, UAE
/in/umarshadab11
INSULATIONS IN HVAC & PLUMBING
PURPOSE OF INSULATION
Insulation is not just wrapping material — it’s a performance component.
• HVAC: Controls heat gain/loss, prevents condensation, improves efficiency, and reduces
noise.
• Plumbing: Maintains water temperature, prevents condensation, reduces corrosion,
and provides fire safety.
TYPES OF INSULATION MATERIALS
(A) Thermal Insulation
Used mainly in chilled water, HVAC ducting, hot water, and plumbing pipes.
1. Fiberglass (Glass Wool)
o Made of spun glass fibers.
o Used in ducts, chilled water pipes, and AHU/FAHU casing.
o Advantages: Lightweight, good thermal resistance, economical.
o Limitations: Absorbs moisture if not vapor-sealed, itchy to handle.
2. Mineral Wool / Rock Wool
o Made from molten rock/basalt fibers.
o Applications: Boilers, hot water pipes, fire-rated ductwork.
o Advantages: High-temperature resistance, soundproofing, fire resistance.
o Limitations: Not good for cold insulation unless vapor-sealed.
3. Elastomeric Foam (Nitrile Rubber / EPDM)
o Flexible closed-cell insulation (brand examples: Armaflex, K-Flex).
o Applications: Chilled water pipes, AC drain lines, refrigerant lines.
o Advantages: Moisture-resistant, flexible, good for cold applications.
o Limitations: Limited temperature range (-40°C to +105°C), UV sensitive unless jacketed.
4. Polyurethane Foam (PUF)
o Rigid foam panels or spray-applied.
o Applications: Pre-insulated pipes, ductwork, tanks.
o Advantages: Very low thermal conductivity, strong, waterproof.
o Limitations: Combustible unless fire-retardant treated.
5. Phenolic Foam
o Closed-cell rigid foam.
o Applications: Duct insulation, pipe sections.
o Advantages: Very low thermal conductivity, fire resistant, lightweight.
o Limitations: Costly, brittle if mishandled.
6. Expanded Polystyrene (EPS) & Extruded Polystyrene (XPS)
o Lightweight foam boards.
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o Applications: Pre-insulated pipes, cold storage.
o Advantages: Good for underground pipe insulation.
o Limitations: Flammable, not UV resistant.
(B) Acoustic Insulation
• Used in HVAC ducts, AHUs, FAHUs, pump rooms.
• Materials: Glass wool, mineral wool, acoustic foam.
• Purpose: Reduce noise & vibration.
(C) Fire-Rated Insulation
• Required for ducts passing through fire zones.
• Materials: Rock wool + fire-rated cladding.
• Purpose: Maintain fire compartment integrity (up to 2 hours).
INSULATION APPLICATIONS IN HVAC
1. Duct Insulation
o Supply ducts (cold air): Thermal insulation + vapor barrier.
o Return ducts: Thermal insulation (no vapor barrier needed).
o Fire-rated ducts: Rockwool + fire-resistant jacket.
2. Chilled Water Pipes
o Elastomeric foam, PUF, phenolic foam.
o Must be vapor sealed to prevent condensation.
3. Hot Water Pipes
o Rock wool or fiberglass with aluminum foil jacketing.
4. Refrigerant Lines
o Elastomeric foam (to prevent condensation & efficiency loss).
INSULATION APPLICATIONS IN PLUMBING
1. Hot Water Supply Pipes
o Rock wool, fiberglass, or elastomeric foam.
o Prevents heat loss.
2. Cold Water Supply Pipes (if required by specs)
o Elastomeric foam with vapor barrier.
o Prevents sweating/condensation.
3. Drainage Pipes (above ceilings)
o Acoustic insulation (glass wool/mineral wool wrap) to reduce flushing noise.
4. Underground Pipes (chilled & potable water)
o Pre-insulated PUF pipes or XPS insulation with waterproofing jacket.
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JACKETING / CLADDING MATERIALS
Insulation alone is weak — jacketing protects it: mostly in wet and exposed area.
• Aluminum sheet (plain or embossed) – common for HVAC pipes & ducts.
• PVC jacket – for elastomeric foam in chilled water pipes.
• Glass cloth + bituminous coating – for underground pipes.
• GI sheet – for duct external cladding.
CONTROL Measures & Site Practices
• Vapor barrier: Essential for chilled water & cold ducts to stop condensation.
• Sealing joints: All gaps sealed with adhesive/tape.
• Support spacing: Pipe hangers should have saddles/inserts to avoid insulation compression.
• UV Protection: Outdoor insulation must be jacketed (aluminum or PVC).
TESTING & INSPECTION
• Thickness Verification: As per design/spec (e.g., 25mm, 50mm).
• Density Check: For rock wool/glass wool (e.g., 48 kg/m³, 64 kg/m³).
• Continuity Check: No gaps or exposed surfaces.
• Vapor Barrier Check: Cold insulation must be sealed.
• Fire Rating: Ensure fire-rated insulations are certified.
COMMON Defects / Mistakes
• Gaps in insulation → condensation.
• Wrong material (hot water pipe insulated with elastomeric foam → failure).
• Missing vapor barrier on chilled water → sweating & dripping.
• Compressed insulation under hangers → thermal bridges.
• Damaged jacketing → water ingress & corrosion.
MAINTENANCE
• Inspect cladding/jacketing for damages.
• Replace wet insulation immediately (loses efficiency).
• Re-seal vapor barrier if peeled.
• Clean ducts to prevent dust sticking to insulation.
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INSULATION THICKNESS REQUIREMENTS
1. Ductwork Insulation
Duct Type Location Typical Thickness Material Used
Supply air ducts 25 mm (phenolic foam / glass wool
Indoor Thermal + vapor barrier
(cold air) with vapor barrier)
With aluminum/PVC
Supply air ducts Outdoor/roof 50 mm
cladding
Thermal only (no vapor
Return air ducts Indoor 25 mm
barrier needed)
50 mm to 80 mm (depending on Rockwool + fire-rated GI
Fire-rated ducts Any
fire rating, 2–4 hrs) cladding
Acoustic lining AHU/FAHU/near
25 mm to 50 mm Glass wool / acoustic foam
inside ducts fans
2. Chilled Water Piping (HVAC)
Pipe Size Location Thickness
Up to 50 mm dia Indoor 25 mm
65 mm – 150 mm
Indoor 32 mm
dia
200 mm – 350 mm
Indoor 38 mm
dia
Above 350 mm dia Indoor 50 mm
Outdoor (exposed Add 9–13 mm more (total ~50–63 mm)
Any size
to sun) with aluminum/PVC cladding
Pre-insulated pipes with PUF (50–100
Underground
mm) + HDPE casing
3. Refrigerant Piping (DX systems / VRF)
Pipe Typical Thickness
Suction line (cold) 19–25 mm elastomeric foam
Liquid line 13–19 mm elastomeric foam
Outdoor exposed Add cladding (UV protection)
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4. Plumbing – Hot Water Pipes
Pipe Size Thickness (Rockwool / Glass Wool / Foam)
Up to 50 mm dia 25 mm
65 mm – 150 mm dia 32 mm
200 mm and above 38–50 mm
Hot water circulating mains 38–50 mm
5. Drainage Pipes (Acoustic Insulation)
Location Thickness Material
Soil/waste pipes (above ceilings in sensitive areas: hotel, Mineral wool / acoustic
25–50 mm
hospital, office, luxury residentials) insulation with PVC jacket
6. Equipment Insulation
Equipment Thickness Material
AHU/FAHU casing (panels) 25–50 mm Glass wool / PUF / phenolic foam
Chiller / Heat exchangers 50 mm Rock wool / PUF
Rock wool / PUF with aluminum/PVC
Storage tanks (hot/chilled water) 50–100 mm
cladding
Quick Notes
• Chilled water: 25–50 mm depending on pipe size.
• Ducts: 25 mm indoor, 50 mm outdoor.
• Hot water: 25–50 mm depending on size.
• Cold water: 19–32 mm elastomeric foam.
• Drainage acoustic: 25–50 mm rockwool.
• Outdoor/roof: Always increase thickness + add aluminum/PVC cladding.
👉👉 This is general practice. Exact thickness is always as per project specification / consultant
requirement / ASHRAE tables.
END OF THE NOTES
UMAR SHADAB
MEP Engineer | Consultant | Certified Lead Auditor ISO 1900:2015 (QMS)
www.linkedin.com/in/umarshadab11 ● umarshadab11@gmail.com
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