FAMCO SDB square to round HVAC transition Box, galvanized steel

FAMCO Square to Round Transition Box Measurement Guide

Square to round duct transition box, front-facing angle.

Side angle of a square to round duct transition.

Square to Round Transition Box

Rated 4.99 out of 5 based on 79 customer ratings

(79 customer reviews)

$28.95 – $91.95

Quality constructed from heavy-duty 28 gauge galvanized steel
Primarily for use to attach a ceiling register to your air supply
Can be used in many applications that transition a square duct to round duct
Available in a variety of common sizes, see the drop down menu for all sizes available

Size

4 inch
5 inch
6 inch
7 inch
8 inch
9 Inch
10 inch
12 Inch
13 Inch
14 Inch
16 Inch
18 Inch
20 Inch

Dimensions

22x22 inch
10 x 8 inch
20 x 20 inch
6x6 inch
8x8 inch
8x16 inch
10x10 inch
12x8 inch
12x10 inch
12x12 inch
14x8 inch
14x10 inch
14x14 inch
15x15 inch
16x16 inch
18x18 inch
24x24 inch

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SKU SDB Categories Accessories, Diffusers

Description

The FAMCO SDB square to round HVAC transition Box – diffuser is designed primarily for use to attach a ceiling register to your air supply, but can be used in many applications that transition a square duct to round duct. Quality constructed from heavy-duty 28 gauge galvanized steel. Available in a variety of common sizes, see the drop down menu for all sizes available. The FAMCO SDB square to round HVAC transition box is manufactured by FAMCO in the United States and comes with a 1-year warranty against product defects and workmanship. If you have any questions about this product, please refer to the FAQs above or feel free to contact us.

PDF Download

Spec Sheet

Square to Round Transition Box

SKU: SDB

Click to Enlarge

Questions and answers of the customers

Does the size pertain to the round duct size?

Q Does the size pertain to the round duct size? answer now
Asked on April 19, 2022 12:26 pm

A
Yes, the "size" selection refers to the round hole size. The "dimensions" selection would be for the square part of the box.

A Yes

A Yes

A A

I have a 18" Round Plenum, need to adapt to Rectangular plenum. is this made to order ?

Q I have a 18" Round Plenum, need to adapt to Rectangular plenum. is this made to order ? answer now
Asked on August 23, 2021 3:21 pm

A
These products are currently manufactured in our Meridian, Idaho factory - the sizes we are able to manufacture are those shown in the dropdown menu.

A No I need a 18x18 square plenum and reduce it to a 12 round

Can these be used for a bathroom exhaust fan intake opening where moist air will travel through the vent?

Q Can these be used for a bathroom exhaust fan intake opening where moist air will travel through t...... Read more answer now
Asked on August 16, 2021 7:55 am

A
We would recommend asking your exhaust fan manufacture for their recommended install method.

I'm looking for something like this but without the "box". I need need to connect round flexible duct to a rectangular hole on the main trunk, but with the "box" there's no mating surface (I need flat sides to secure with sheet metal screws). I suppose I could break the welds and hammer the sides flat but do you have a product like I'm describing? I can find them in plastic but would prefer galvanized aluminum. Thanks.

Q I'm looking for something like this but without the "box". I need need to connect round flexible ...... Read more answer now
Asked on August 12, 2021 7:52 am

A
This is not something that we currently supply or manufacture.

A The magic phrase is Start Collar. You need a start collar, either buy it (somewhere), or watch a YouTube video.

I need a 13"×14"×6"round

Q I need a 13"×14"×6"round answer now
Asked on July 29, 2021 7:24 pm

A
This is not a size we are currently able to manufacture, unfortunately.

I need a 24" x 24" and 14" diameter transition box. Do you have this size? Thanks

Q I need a 24" x 24" and 14" diameter transition box. Do you have this size? Thanks answer now
Asked on June 16, 2021 11:48 am

A
Yes - this is a size we are currently able to manufacture, you can select these dimensions in the dropdown.

If I order today ..which one is the delivery date? thanks

Q If I order today ..which one is the delivery date? thanks answer now
Asked on June 12, 2021 12:58 pm

A
Current manufacturing and shipping estimates are given in the shopping cart and at checkout.

I need a 10"w x 3-1/4 to a "6 inch-round

Q I need a 10"w x 3-1/4 to a "6 inch-round answer now
Asked on May 18, 2021 5:49 pm

A
This is not a size we currently manufacture, unfortunately.

Do you make w 16”. L18” round 14. Duct adapter

Q Do you make w 16”. L18” round 14. Duct adapter answer now
Asked on May 2, 2021 12:06 pm

A
We currently only manufacture the sizes shown in the dropdown menu

Do you make these in 18Wx18Lx12D

Q Do you make these in 18Wx18Lx12D answer now
Asked on April 25, 2021 1:05 pm

A
Yes - all sizes available can be selected in the dropdown on the product page.

Could we order this for a custom size box of 16 x 25 in square and 8-inch diameter circle? Thank you.

Q Could we order this for a custom size box of 16 x 25 in square and 8-inch diameter circle? Thank ...... Read more answer now
Asked on October 25, 2020 11:17 pm

A
We currently only offer customization on volume runs with a total value greater than $5,000

79 reviews for Square to Round Transition Box

5.0

Based on 79 reviews

5 star	98	98%
4 star	1	1%
3 star		0%
2 star		0%
1 star		0%

Showing 78 of 79 reviews (5 star). See all 79 reviews

Rated 5 out of 5

Chris – May 9, 2018

Good quality

Pretty basic square to round transition, but very well made. Ordering was easy and it got here pretty quick. The only problem was on my end, I ordered the wrong size. I needed a 12″ instead of the 14″. Oh well, I can always let my boss have them and consider it another example of the woodworkers maxim: “Measure twice. Cut once.”
Rated 5 out of 5

Christopher T. (verified owner) – January 31, 2019

I had a question about dimension, they responded within an hour and order was made, item arrived a week later just as I had hoped. Great experience.
Rated 5 out of 5

R ALLEN (verified owner) – April 1, 2019

The part looks nice and it was built and shipped quickly!
Rated 5 out of 5

Anonymous (verified owner) – May 27, 2019
Rated 5 out of 5

Shannon (verified owner) – June 9, 2019

This arrived in perfect condition and fit exactly how I needed.
Rated 5 out of 5

Andrew (verified owner) – June 29, 2019

Thanks for making these available and easy to order. Great quality. Good shipping process.
Rated 5 out of 5

Hugh Siebenthall (verified owner) – July 28, 2019

My order was small and of little consequence to your overall operation. You followed through precisely as stated. Thank you and your entire team.
Rated 5 out of 5

Tim Thompson (verified owner) – August 18, 2019
Rated 5 out of 5

Anonymous (verified owner) – August 20, 2019
Rated 5 out of 5

john d. (verified owner) – August 22, 2019

Quick and easy to order. Arrived in perfect condition. Good price.
Rated 5 out of 5

John B. (verified owner) – September 23, 2019
Rated 5 out of 5

tony ozark (verified owner) – September 30, 2019

Perfect!
Rated 5 out of 5

Roy Oldaker (verified owner) – October 1, 2019
Rated 5 out of 5

Dan (verified owner) – October 6, 2019
Rated 5 out of 5

Jose Gonzales (verified owner) – October 28, 2019

Thank you! It was both put together and priced very well!
Rated 5 out of 5

Richard Plenert (verified owner) – October 28, 2019
Rated 5 out of 5

John Garbarino (verified owner) – December 16, 2019

Great company ford hard to find stuff fast shipping
Rated 5 out of 5

Anonymous (verified owner) – December 21, 2019
Rated 5 out of 5

mark t. (verified owner) – December 26, 2019

The transition box I ordered fit perfectly around my water to air heat exchanger. And very good build quality.
Rated 5 out of 5

Nick D. (verified owner) – January 10, 2020
Rated 5 out of 5

Josefa Barreiro (verified owner) – February 8, 2020
Rated 5 out of 5

Anonymous (verified owner) – February 11, 2020
Rated 5 out of 5

Josef (verified owner) – February 20, 2020

Quality product, no problem with any phase of this order. Thanks!!!!!
Rated 5 out of 5

Kendall Marks (verified owner) – March 8, 2020

Excellent value, fast delivery
Rated 5 out of 5

Joseph Firrantello (verified owner) – March 31, 2020

Product was perfect for my needs. Received quickly.
Rated 5 out of 5

Anonymous (verified owner) – April 4, 2020
Rated 5 out of 5

Matthew T. (verified owner) – April 13, 2020

Perfect!!!! Very happy!!! Will buy here again!!
Rated 5 out of 5

Hector cruz (verified owner) – April 16, 2020

👍
Rated 5 out of 5

Andrew (verified owner) – April 26, 2020

Great craftsmanship
Rated 5 out of 5

James G. (verified owner) – May 4, 2020

Awesome! This has been a life saver. I bought this to help redirect heat from the furnace in my RV. It used to blow straight onto the thermostat so it never got warm inside and the furnace kept kicking on and off. Now i’ve successfully redirected all the heat and it works like it should. Haven’t burned the place down yet either!
Rated 5 out of 5

Jessica (verified owner) – May 4, 2020
Rated 5 out of 5

Glenn Fulmer (verified owner) – June 12, 2020

Great fit and great construction.
Rated 5 out of 5

Mike M. (verified owner) – June 12, 2020

Beautiful product, arrived quickly!
Rated 5 out of 5

Ralph P. (verified owner) – June 14, 2020

The product was excellent quality and fit perfectly
Rated 5 out of 5

Ralph (verified owner) – June 25, 2020

Well made u band exactly what I wanted.
Rated 5 out of 5

Bud C. (verified owner) – July 7, 2020

As advertised, shipped promptly, very high quality product. Shipping cost was high but would buy from Famco again.
Rated 5 out of 5

Bennie Keisling (verified owner) – July 13, 2020

Good quality & fast delivery!
Rated 5 out of 5

Ryan (verified owner) – August 8, 2020

I put up new drywall for home renovations and in the process needed to move my return line for the a/c. The dimensions of my old return box were too large for the vent cover I needed, so I ordered a custom transition box from FAMCO. It arrived exactly as what I ordered and made the job easy to finish. And it was quite a bit cheaper than other competitors. I will definitely keep FAMCO in mind for any projects in the future.
Rated 5 out of 5

Jake M. (verified owner) – August 18, 2020

Fast shipping and exactly what I was looking for. Came well packaged and the manufacturing was top quality. Thank you
Rated 5 out of 5

Steve Chayer (verified owner) – September 8, 2020

Trustworthy. Have confidence in this company for delivery times and quality of product.
Rated 5 out of 5

Gregory R. (verified owner) – September 22, 2020
Rated 5 out of 5

Wayne Cox (verified owner) – September 28, 2020

I love these people at Famco. They have never let me down. They always ship when they say they are going to ship, I highly recommend them.
Rated 5 out of 5

Armand (verified owner) – November 6, 2020

The transition box was very well made, and arrived in a timely manner.
Rated 5 out of 5

Peter Saloufakos (verified owner) – November 21, 2020

Fits perfect.
Rated 5 out of 5

Paul Scholer (verified owner) – December 2, 2020
Rated 5 out of 5

Bart Domingue (verified owner) – December 6, 2020

Very satisfied
Rated 5 out of 5

Gordon Rhodes (verified owner) – December 11, 2020
Rated 5 out of 5

Loreimy Panchis (verified owner) – January 8, 2021
Rated 5 out of 5

Anonymous (verified owner) – January 17, 2021

Custom product not found elsewhere. Exactly what I needed.
Rated 5 out of 5

Alexis B. (verified owner) – January 25, 2021
Rated 5 out of 5

Kevin K. (verified owner) – February 5, 2021
Rated 5 out of 5

Herbert West (verified owner) – February 14, 2021
Rated 5 out of 5

Charles R. (verified owner) – February 15, 2021
Rated 5 out of 5

Robert (verified owner) – March 13, 2021

Dimensions are true as shown online. Well made. My project required a flat black finish. The FAMCO box painted up well. I primed before applying the final coat.
Rated 5 out of 5

Jim G. (verified owner) – March 29, 2021

Well made product, worked perfectly
Rated 5 out of 5

Anonymous (verified owner) – March 30, 2021
Rated 5 out of 5

David S. (verified owner) – April 2, 2021
Rated 5 out of 5

Clay (verified owner) – September 23, 2021

Fit perfectly with high quality fabrication.
Rated 5 out of 5

Pat Urlacher (verified owner) – October 25, 2021

Great product fitment was right on the money.👍👍👍👍
Rated 5 out of 5

David Watson (verified owner) – April 18, 2024

Well made and dimensions were spot on. Replaced old hood vent, which had a 6″ square exit. New vent has 6″ round. And slightly offset.
Rated 5 out of 5

Brian (verified owner) – April 25, 2024

Item exactly as described/ordered.
Rated 5 out of 5

Anonymous (verified owner) – April 30, 2024
Rated 5 out of 5

Anthony (verified owner) – June 7, 2024
Rated 5 out of 5

Jason McLeod (verified owner) – June 12, 2024
Rated 5 out of 5

Andrew R. (verified owner) – June 16, 2024
Rated 5 out of 5

George Bowersox (verified owner) – June 30, 2024
Rated 5 out of 5

Michael (verified owner) – July 1, 2024

It’s made to perfection!
Rated 5 out of 5

MICHAEL B. (verified owner) – July 6, 2024

Transition from round to square went perfect!
Rated 5 out of 5

MICHAEL B. (verified owner) – July 6, 2024
Rated 5 out of 5

Andy – August 9, 2024

Great product and pricing and the quality of workmanship is the best
Rated 5 out of 5

Paul (verified owner) – August 12, 2024
Rated 5 out of 5

Shawn Greaney (verified owner) – November 10, 2024
Rated 5 out of 5

Jeremy Hudson (verified owner) – November 18, 2024
Rated 5 out of 5

Anonymous (verified owner) – November 30, 2024

Appears to be good quality and was the perfect solution for connecting a new range hood to a square ceiling duct in my 1950s home. Price was a bit more than I hoped to pay but is not unreasonable for a made-to-order item that solved a headache for me.
Rated 5 out of 5

Russell Patterson (verified owner) – December 7, 2024

Prices are excellent compared to other competitors!
Rated 5 out of 5

Russell Patterson (verified owner) – December 28, 2024
Rated 5 out of 5

Cesar DOliveira (verified owner) – March 4, 2025

Great quality
Rated 5 out of 5

Cesar DOliveira (verified owner) – March 15, 2025