4000706 – REDUCER
These ship UNCRIMPED on both ends - if you are going into metal pipe you crimp one end yourself. That is on purpose: it lets you pick which end is male when you are working into an existing run. Point the crimped end downstream with the airflow and seal the joint with mastic or foil tape.
10226 Plano Rd, Suite 104, Dallas TX 75238
Questions? Call or text (214) 340-9421
Mon–Fri 10 am – 7 pm | Sat 10 am – 3 pm
A duct reducer transitions between two different round duct sizes in your supply or return air system. Use one when you need to connect a 7″ duct run to a 6″ branch, or when stepping down from a trunk line to a smaller run. Galvanized steel construction holds up in attics, crawlspaces, and walls.
Specs: 7″ to 6″ round duct reducer, galvanized steel, crimped on small end for slip-fit connection
Replaces: 4000706
Fits: Standard 7″ to 6″ round ductwork. Universal fit — works with all HVAC brands and systems.
In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.
Specs
- TypeSheet metal duct reducer
- Transition7" to 6"
- Large end7"
- Small end6"
- EndsUncrimped both ends - crimp one end yourself to fit into metal pipe
- OrientationCrimped male end points downstream, with the airflow
- SealingMastic or foil tape at the joint
Cross-reference numbers
This part replaces the following OEM and aftermarket numbers:
- 4000706
- 40076
- ELKHARTCOPPER
- ELKHARTCOPPERFITTINGEQUIVALENT
- MUELLERCOPPER
- MUELLERCOPPERFITTINGEQUIVALENT
- SMITH-COOPERBRASS
- SMITH-COOPERBRASSFITTINGEQUIVALENT
Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.
What size reducer do I need?
Reducers are named large end first, then small end. A 16 x 14 reducer takes 16 inch duct down to 14 inch. Measure the two runs you are joining, not the fittings on them.
Do I need to crimp it?
Yes, on metal. Ours ship UNCRIMPED on both ends, so you crimp the end that has to slide inside the next section of pipe with a hand crimper. Uncrimped means you decide which end is male, which is what you want when you are fitting into an existing run.
Which way does it go in the duct run?
The crimped male end points downstream, in the direction the air is moving, so each joint laps with the airflow instead of catching it. Seal the joint with mastic or foil tape - cloth duct tape is not a duct sealant despite the name.
Does reducing the duct hurt airflow?
Every reduction speeds the air up and raises static pressure, which the blower has to fight. That is normal where the design calls for it as a trunk tapers, but reducing just to make a fitting work is how you end up with noisy vents and a system that runs long.
Can I jump several sizes in one reducer?
You can, but an abrupt step creates turbulence and noise. Stepping down gradually along the trunk moves air more quietly and with less pressure loss.
Do you stock the sizes between?
We carry the common residential steps from 5 inch up to 16 inch on the shelf at 10226 Plano Rd, Suite 104 in Dallas.
