Downdraft Ventilators | McMaster-Carr

Measured in decibels (dB), volume ratings indicate how much noise equipment makes. Some common volume levels include a whisper @ 20 dB, a refrigerator @ 40 dB, a conversation @ 60 dB, and a light machine shop @ 90 dB. OSHA recommends hearing protection for exposure to 80 dB and greater.

Direct-Drive Downdraft Roof-Mount Exhaust Fans

Direct-drive fans have fewer moving parts than belt-drive fans for less maintenance. More economical than upblast roof-mount exhaust fans, these draw stagnant and humid air out through your roof and then direct it back toward the roof. All fans have a disconnect switch to turn off the power for servicing.

Fans with a brushless motor are more efficient than fans with a standard motor. They operate at a wide range of speeds for precise speed control and greater energy savings. They’re also quieter and have a longer lifespan because of their advanced electronic controls.

Note: Airflow depends on the resistance created by ductwork. This resistance, known as static pressure (SP), is measured in inches of water.

Fans
						Overall									Mounting Bases
	Blade Dia.	Airflow @ Static Pressure	Volume	Motor Speed, rpm	Power, hp	Dia.	Ht.	Base Wd.	Wt., lbs.	Max. Ambient Temp., °F	Housing Material	Specifications Met		Each		Each
Totally Enclosed Motor Enclosure
120V AC, Single Phase—Hardwire
1	10"	60 cfm @ 1/2 in. of H₂O 500 cfm @ 0 in. of H₂O	Not Rated	1,500	1/30	18 5/16"	11 1/4"	19"	21	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	0000000	0000000	0000000
1	12"	430 cfm @ 1/2 in. of H₂O 830 cfm @ 0 in. of H₂O	Not Rated	1,500	1/10	20 5/16"	11 3/4"	19"	30	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
1	14"	520 cfm @ 1/2 in. of H₂O 1,100 cfm @ 0 in. of H₂O	Not Rated	1,100	1/6	27 5/16"	14 5/8"	21"	39	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
1	18"	1,200 cfm @ 1/2 in. of H₂O 2,400 cfm @ 0 in. of H₂O	Not Rated	1,100	1/3	33 9/16"	16 3/8"	26"	60	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
Totally Enclosed Motor Enclosure—Brushless Motor
120V AC, Single Phase—Hardwire
2	12"	1,000 cfm @ 1/2 in. of H₂O 1,300 cfm @ 0 in. of H₂O	66 dBA @ 5 ft.	1,575	1/3	26 1/4"	19 1/8"	21"	54	120°	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
2	14"	1,900 cfm @ 1/2 in. of H₂O 2,300 cfm @ 0 in. of H₂O	68 dBA @ 5 ft.	1,525	1/2	29 3/4"	21 3/4"	21"	61	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000
2	16"	2,850 cfm @ 1/2 in. of H₂O 3,300 cfm @ 0 in. of H₂O	71 dBA @ 5 ft.	1,525	1	33 1/4"	23 3/8"	24"	74	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000
Open Dripproof Motor Enclosure
120V AC, Single Phase—Hardwire
2	9"	100 cfm @ 1/2 in. of H₂O 400 cfm @ 0 in. of H₂O	50 dBA @ 5 ft.	1,250	1/32	20 3/4"	14 1/2"	19"	40	120°	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
2	11"	600 cfm @ 1/2 in. of H₂O 800 cfm @ 0 in. of H₂O	57 dBA @ 5 ft.	1,625	3/16	23 3/4"	16 1/4"	19"	37	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
2	12"	950 cfm @ 1/2 in. of H₂O 1,250 cfm @ 0 in. of H₂O	62 dBA @ 5 ft.	1,625	1/4	26 1/4"	19 1/8"	21"	53	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
2	14"	1,800 cfm @ 1/2 in. of H₂O 2,100 cfm @ 0 in. of H₂O	66 dBA @ 5 ft.	1,625	1/2	29 3/4"	21 3/4"	21"	56	Not Rated	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
2	16"	2,600 cfm @ 1/2 in. of H₂O 3,100 cfm @ 0 in. of H₂O	70 dBA @ 5 ft.	1,450	3/4	33 1/4"	23 3/8"	24"	77	120°	Aluminum	AMCA Certified, ETL Listed	0000000	000000	0000000	000000
208/230V AC, Three Phase—Hardwire
3	19"	4,500 cfm @ 1/2 in. of H₂O 5,000 cfm @ 0 in. of H₂O	75 dBA @ 5 ft.	1,300	2	38 15/16"	32 3/4"	28"	189	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000
3	21"	6,200 cfm @ 1/2 in. of H₂O 6,700 cfm @ 0 in. of H₂O	82 dBA @ 5 ft.	1,400	5	38 15/16"	32 1/4"	28"	201	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000
3	24"	8,100 cfm @ 1/2 in. of H₂O 9,000 cfm @ 0 in. of H₂O	73 dBA @ 5 ft.	925	3	43 7/16"	37 1/4"	33"	288	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000
3	30"	10,400 cfm @ 1/2 in. of H₂O 11,500 cfm @ 0 in. of H₂O	69 dBA @ 5 ft.	700	5	52 13/16"	44"	40"	467	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000
3	36"	11,000 cfm @ 1/2 in. of H₂O 13,500 cfm @ 0 in. of H₂O	64 dBA @ 5 ft.	450	5	63 5/16"	49 1/2"	44"	532	120°	Aluminum	AMCA Certified, ETL Listed	0000000	00000000	0000000	000000

Belt-Drive Downdraft Roof-Mount Exhaust Fans

Belt-drive fans are quieter and have a longer life span than direct-drive fans because components can be replaced if worn or damaged. More economical than upblast roof-mount exhaust fans, these draw stagnant and humid air out through your roof and then direct it back toward the roof.

Note: Airflow depends on the resistance created by ductwork. This resistance, known as static pressure (SP), is measured in inches of water.

Fans
					Overall						Mounting Bases
Blade Dia.	Airflow @ Static Pressure	Volume	Motor Speed, rpm	Power, hp	Dia.	Ht.	Base Wd.	Housing Material		Each		Each
Open Dripproof Motor Enclosure
120/208-230V AC, Single Phase—Hardwire
16"	2,800 cfm @ 1/2 in. of H₂O 3,200 cfm @ 0 in. of H₂O	70 dBA @ 5 ft.	1,145	3/4	33 11/16"	29 1/4"	26"	Aluminum	0000000	000000000	0000000	0000000
20"	4,900 cfm @ 1/2 in. of H₂O 5,400 cfm @ 0 in. of H₂O	74 dBA @ 5 ft.	1,080	1 1/2	38 1/4"	31 3/4"	30"	Aluminum	0000000	00000000	0000000	000000
208-230/460V AC, Three Phase—Hardwire
24"	6,900 cfm @ 1/2 in. of H₂O 7,750 cfm @ 0 in. of H₂O	73 dBA @ 5 ft.	875	2	44 1/4"	39 11/16"	33"	Aluminum	0000000	00000000	0000000	000000