HVACopediaTrane · Furnace troubleshooting
Wall vent clearances and shielding
What is going on
Clearances depend on wall construction and vent material. Combustible walls need an air space and a shield, and wall-vent flue gas can damage nearby materials.
Check in this order
- Use 0 in clearance to combustible walls for PVC vent pipe.
- Use 1 in clearance to combustible walls for Type 29-4C stainless vent pipe.
- Hold a 1 in air space at combustible walls where the wall pipe passes through, and set the approved termination in place.
- Seal noncombustible wall penetrations with cement mortar inside and outside, with the hole sized to keep pitch and seal properly.
- Where flue gas could damage the wall, install a corrosion-resistant shield, at least 24 gauge stainless or aluminized, minimum 12 in x 12 in, fastened to both the inside and outside of the wall.
- Silicone-caulk all cracks, seams and joints within 3 ft of the vent terminal.
Applies to: Horizontal wall venting
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Source: Trane installer's guide, p. 25. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.