QUOTE LINE ITEM · LAST CHECKED NOVEMBER 4, 2026
Ductwork changes on a heat pump quote: what it should say
Quick answer
For a ducted heat pump, a quote should say whether the installer inspected your ducts, whether they are sized for the new system’s airflow, and what sealing, repair or new ductwork is included. “Connect to existing ductwork” alone tells you nothing about whether the ducts will work well.
What a complete quote states
- Whether existing ducts were inspected and whether static pressure or airflow was measured.
- Specific changes included: new return, larger trunk, sealing, insulation, new registers.
- Whether duct sealing is included, and how leakage will be tested if at all.
- For ductless or mixed systems, which rooms rely on ducts and which on indoor heads.
Red flags when it is missing or vague
- “Tie into existing ductwork” with no inspection noted.
- No mention of return air, when a heat pump often needs more airflow than the old furnace.
- Ducts in an attic or crawlspace with no mention of sealing or insulation.
- Duct work “as needed” or “time and materials”.
Three questions to send the installer
- Did you inspect my ducts or measure static pressure? Are they sized for the airflow the new heat pump needs?
- Which duct changes, sealing or insulation are included in the total, and which would be extra?
- How will you confirm the airflow is correct after installation?
Why two quotes differ here
This is where a lower quote can quietly become an expensive one. Heat pumps often need more airflow than the furnace they replace. Undersized or leaky ducts can make a correctly sized heat pump noisy, uncomfortable or inefficient. One installer may price fixing that up front; another may assume the ducts are fine.
Ask each installer to state what they observed. If only one measured, that quote may be the more reliable one even if it costs more.
What the sources say
ENERGY STAR says that in a typical house “about 20 to 30 percent of the air that moves through the duct system is lost”, and advises: “Ask your contractor to inspect your home’s duct system, perform a leakage test, and make necessary repairs,” and to “ensure that your new system’s airflow meets manufacturer performance specifications.” It recommends mastic or metal tape: “Never use duct tape.”
ACCA Manual D is the ANSI-recognized duct design method. Some programs ask for it: Mass Save’s sizing bonus form says “Manual J, S, and/or Manual D documentation required,” and Efficiency Maine’s ducted checklist requires sealed seams and insulation of at least R-8 in unconditioned basements and R-12 in other unconditioned spaces.
Cost
A January 2025 DOE report modeling home upgrade costs assumed $4,999 for duct upgrades in a cold-climate single-family detached home ($9.30 per square foot of duct surface area). DOE calls this “a conservative assumption, and many homes may not need such duct upgrades.” It’s a modeling figure, not a market price. Ask each installer for duct work as its own line.
Sources
- Duct sealing (ENERGY STAR)
- HVAC Quality Installation (ENERGY STAR)
- Manual D (ACCA)
- Heat Pump Space Heating Permitting & Inspection Checklist (PDF) (New Buildings Institute for the U.S. DOE, page dated October 2024)
- Efficiency Maine heat pump installation checklist (PDF) (Efficiency Maine, page dated January 1, 2026)
- Mass Save 2026 air-source heat pump rebate form (PDF) (Mass Save sponsors, page dated 2026 installs)
- Affordable Home Energy Shot target-setting methodology (PDF) (U.S. DOE, page dated January 2025)
Holding two or three quotes? Mark Installation labor as Included, Excluded or Unclear for each quote and get one question list per installer. Nothing is uploaded.
Last checked: . Informational only. This is not financial, tax, legal or professional installation advice, and we do not verify any installer’s work.