HVACQuick - Fantech RSK Backdraft Dampers

model	description	usually ships	price
RSK 4	Fantech Spring Loaded Backdraft Damper. For 4" Round Duct	1 Day. In-stock	$19.50
RSK 5	Fantech Spring Loaded Backdraft Damper. For 5" Round Duct	1 Day. In-stock	$24.70
RSK 6	Fantech Spring Loaded Backdraft Damper. For 6" Round Duct	1 Day. In-stock	$26.40
RSK 8	Fantech Spring Loaded Backdraft Damper. For 8" Round Duct	1 Day. In-stock	$31.40
RSK 10	Fantech Spring Loaded Backdraft Damper. For 10" Round Duct	1 Day. In-stock	$45.40
RSK 12	Fantech Spring Loaded Backdraft Damper. For 12" Round Duct	1 Day. In-stock	$56.90

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fantech rsk

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#1	Q: I am looking for a spring-loaded backdraft damper, 3 3/4 inches in diameter and 3 inches long. This will replace the bathroom exhaust fan damper without removing the existing assembly in my apartment, avoiding tile and wall work. So I can slide it into the existing space. Any suggestions? Thx. A: Take a look at the Artis Metals backdraft dampers. The 4 inch size is 3-5/8 diameter: https://www.hvacquick.com/products/residential/Kitchen-Exhaust/Silencers/Artis-Metals-Butterfly-Backdraft-Dampers Asked on 2026-08-26 by Hach
#2	Q: I know that I need to update backdraft protection in my bathroom due to elevated humidity levels, but its not clear whether I should start with an in-line damper like this Fantech RSK, or one of your VMAX-AF Series Exhaust Vent Hoods (or both). Would stacking dampers risk causing the exhaust vent hood damper not to open? A: We would recommend starting with a backdraft damper near the bath ceiling to stop humid air from travelling into the duct which can cause condensation when the fan is off in cold climates. As far as having a second damper in the hood that is a good idea assuming your fan is reasonably strong. Asked on 2026-07-18 by Andrew
#3	Q: What is the ideal position in the exhaust line for the damper (I.e. immediately following the liner, immediately preceding the fan or immediately after the fan)? Also, the ducting will be at a 45* angle to the roof. Will this impact the performance? A: Ideally you want it just after the liner or just above the transition from kitchen ceiling to attic space. That way its at the transition from heated to unheated space and accessible if it needs servicing. 45 deg is fine but align the center shaft so its vertical. That ensures both butterfly sections have equal force of gravity on them. Asked on 2025-11-17 by TM
#4	Q: How much pressure or inches of water column does the damper need to overcome the spring pressure and stay open? On a 6 and or 8 exhaust vent A: Fantech (nor any other backdraft damper manufacturer we carry) publishes these specs. The only guidance they provide is that the spring is sized for typical airflow. Sorry. Asked on 2022-09-07 by Jason
#5	Q: What is the maximum allowable back pressure for 8-inch Fantech RSK? Can it hold against 1.5 inches without damage? A: There is no official rating. 1.5 in w.g. should not be a problem. Asked on 2021-10-24 by cs
#6	Q: Do you have a backdraft damper for 7 in. duct? A: We do not. Sorry. Asked on 2021-04-22 by JK
#7	Q: Is there any reason I shouldnt install these at the end of horizontal, round residential HVAC supply ducts, just before they covert to square boxes, where my supply vents/registers are? The purpose would be to help reduce noise transferred through the ducts while the fan/heat/AC is not running. A: I think you would find there is not enough air flow in most AC ducts to fully open these. The springs are sized for exhaust fans which are typically more airflow in the same size duct. Asked on 2020-07-26 by Patrick
#8	Q: Can the damper be used in a horizontal position but in downflow? A: No. The spring/damper weight is balanced for upflow (upwards exhaust air flow) or sideways flow. It would not close if installed upside down. Asked on 2020-07-12 by Mark
#9	Q: Will this damper reduce kitchen noise for a wall mounted kitchen range hood? A: The damper will not help with any noise your fan generates. Its strictly there to help prevent backdrafting. Asked on 2016-09-12 by Seyi
#10	Q: Can spring loaded backdraft dampers be used on clothes dryer vents without causing a fire hazard? A: Backdraft dampers are not recommended. The central pivot will catch lint. Asked on 2015-02-23 by CJD
#11	Q: My roof is pitched perhaps 30 degrees. Should I install this at the roof line attached to the starter collar on my roof vent (damper would be at an angle) or completely vertically further down the duct run on top of the mounted fantech fan? A: They can go most anywhere, but the preferable location is at the roof cap so it stops the air right at the penetration of the envelope. Asked on 2014-10-25 by California
#12	Q: Where in a bathroom system, with flexible insulated duct, an inline fan and then a roof cap is the best place to install the damper? A: We like to put them right beneath the roof cap to stop any air intrusion to the building envelope, but anywhere in the duct is fine. Asked on 2014-04-08 by CMO
#13	Q: Can I put one of these spring loaded back draft dampers in a dryer vent line? A: It can be done, but it is not recommended unless it can be serviced. Typically the backdraft is handled at the discharge hood. Asked on 2014-04-04 by David
#14	Q: My existing vent wall cap for my range hood has a damper that flaps with slightest breeze. If I install the Fantech damper do I remove this cap damper or should I replace the wall cap as well? A: It couldnt hurt to have both dampers...I would try adding a bit of weight to the exterior flap to help it seat a little better as well. Asked on 2013-11-21 by Skokie, Illinois
#15	Q: Can I mount a backdraft damper horizontally? Also, are these ok for a kitchen exhaust? A: If you able to have some tilt in the pipe to keep it closed you can, but it is advisable to use them in a vertical orientation. These are just fine for kitchens as well. Asked on 2013-04-04 by MM

Fantech RSK Backdraft Dampers

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