Ductwork (H03)
Ductwork is your HVAC system’s circulatory system – poor duct design causes hot and cold rooms, wasted energy, and premature equipment failure.
This BidScope guides you through duct systems: supply ducts delivering conditioned air to rooms, return ducts bringing air back to equipment, proper sizing for airflow requirements, and sealing to prevent leakage.
Learn duct materials: sheet metal (galvanized steel most durable, professional installation required), flex duct (insulated flexible duct, easier to install but can restrict airflow if kinked or compressed), duct board (fiberglass, insulation and duct in one, economical).
Understand duct sizing: Manual D calculation matches duct size to HVAC capacity, undersized ducts restrict airflow and reduce efficiency, oversized ducts waste money without benefit, velocity considerations (600-900 FPM in residential).
Master sealing requirements: Utah energy code requires duct leakage testing (maximum 6% leakage to outside conditioned space), mastic sealant or approved tape at joints, metal tape not cloth duct tape.
Navigate insulation: supply ducts in unconditioned spaces need R-6 or R-8 insulation minimum, return ducts also need insulation to prevent condensation, vapor barrier facing outward.
Learn proper installation: adequate support every 4-6 feet, avoid compression of flex duct, straight runs where possible, proper boot connections at registers.
Understand common problems: disconnected ducts waste 20-40% of conditioned air, crushed flex duct in attics, inadequate return air (common cause of comfort problems), leaks at joints.
Know when duct repair makes sense versus replacement.
Navigate additions and modifications: adding zones or registers, return air upgrades, duct cleaning (benefits debated, only needed if visible mold or debris).
Calculate typical costs: duct sealing $300-1,000, new ductwork $3,000-10,000+ depending on size and complexity.
This tool ensures your ductwork delivers conditioned air efficiently to every room.
What’s Included:
- Ductwork system components (supply, return, plenums, registers)
- Supply ducts (deliver conditioned air to rooms)
- Return ducts (bring air back to equipment)
- Return air adequacy (common deficiency)
- Plenum boxes (distribution from equipment)
- Duct materials (sheet metal, flex duct, duct board)
- Sheet metal ductwork (galvanized steel, most durable, professional install)
- Rectangular vs round duct
- Flex duct (insulated flexible, easier install, can kink)
- Duct board (fiberglass, insulation and duct combined)
- Duct sizing calculations (Manual D)
- CFM requirements by room
- Duct size by airflow (larger rooms need bigger ducts)
- Velocity considerations (600-900 FPM residential)
- Undersized duct problems (restriction, noise, inefficiency)
- Oversized duct problems (waste, settling)
- Duct sealing requirements (Utah code max 6% leakage)
- Duct leakage testing and verification
- Mastic sealant at joints
- Metal tape vs cloth duct tape (cloth prohibited)
- Duct insulation requirements
- R-6 or R-8 minimum in unconditioned spaces
- Supply duct insulation in attics and crawl spaces
- Return duct insulation (prevent condensation)
- Vapor barrier facing outward
- Proper duct installation (support, routing, connections)
- Duct support hangers every 4-6 feet
- Avoid compression of flex duct
- Straight runs minimize resistance
- Boot connections at registers
- Transition fittings and elbows
- Dampers for zone control
- Common ductwork problems
- Disconnected ducts (20-40% air loss typical)
- Crushed or kinked flex duct in attics
- Inadequate return air (comfort and efficiency issues)
- Leaking joints and seams
- Duct in unconditioned space without insulation
- Duct repair vs replacement decisions
- Signs needing duct replacement
- Ductwork modifications (additions, zone upgrades)
- Adding registers and branches
- Return air upgrades
- Converting from single return to multiple
- Duct cleaning (only needed if visible mold or debris)
- Benefits of duct cleaning debated
- Duct design for new construction vs retrofit
- Cost factors ($300-1,000 sealing, $3,000-10,000+ new ductwork)
- Finding qualified duct contractors
- HVAC contractor vs specialized duct installer
- Energy audits and duct evaluation
