Forced-air heat became the norm in post-war Denver suburbs, and plenty of ranches in Lakewood, Aurora and Westminster still have ductwork from the original build. Over the years furnaces have been swapped, but the trunk lines, the old collars at the furnace and the tape at joints often stay. Some older duct insulation, joint tape, furnace gaskets and the paper-like wrap on some ducts may contain asbestos.
Most furnace installers know the drill for a modern unit. Fewer slow down to ask whether the white tape at a seam is a newer foil product or decades-old fibrous material. As the owner, you can raise the question before the job is scheduled.
Suspect spots around an older forced-air system
- Fabric-like or paper-like wrap on supply and return ducts.
- White, gray or brittle tape at duct joints and collars.
- Gasket or rope-like seals on older furnace doors and flue connections.
- Insulation lining the inside of older plenums.
- Vent connector material between the furnace and chimney.
- Flooring and ceiling materials the installers may cut to reroute ducts.
What a replacement job may disturb
| Job step | Possible suspect material | Ask |
|---|---|---|
| Disconnecting the old furnace | Duct tape, collars, internal gaskets | Will these be sampled first? |
| Cutting new duct openings | Older wrap or insulation, floor tile, ceiling texture | Which surfaces will be cut? |
| Relining or replacing the flue | Older vent connector materials | Is the existing vent part of the scope? |
| Hauling the old unit away | Any internal insulation left inside | Where will the unit be disposed of? |
Deciding what to do before installation day
- IfDucts and tape look like newer metal and foil productsThenAsk the installer to confirm, and proceed as normal if they agree nothing suspect is involved.
- IfYou see fibrous wrap, older tape or anything you cannot identifyThenHave a certified inspector sample those materials before the installation date.
- IfSamples are positiveThenSchedule certified abatement of the affected sections before the installer disconnects anything.
- IfThe installer says it is fine without looking closelyThenAsk for a written statement of what they will disturb, and consider sampling anyway.
Common questions
Do furnace installers need asbestos certification?
Installers are not abatement contractors. If asbestos-containing material must be removed for the installation, that portion should be handled by appropriately certified personnel. Ask how the installer coordinates with them.
General information for the Denver area, not a quote or professional advice. In an emergency, call 911.