Bath Exhaust Fan Duct Insulation
Why & how should we insulate the exhaust duct on a bathroom exhaust fan system?
BATHROOM VENT DUCT INSULATION - CONTENTS: about recommendations for bath exhaust vent duct insulation: avoid condensation & related leaks from bathroom moisture passing through the fan and vent system.
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Bath Exhaust Fan Duct Insulation: how should we insulate the exhaust duct on a bathroom exhaust fan system to prevent condensation and leaks into the building or wall?
This article series explains how to install bathroom exhaust fans or vents, the vent ducting, the vent termination at the wall, soffit or roof, vent fan wiring, bath vent duct insulation, bath vent lengths, clearances, routing, and we answer just about any other bathroom ventilation design or installation question you may have.
Insulate the bathroom exhaust vent fan ducts: In un-conditioned space such as an attic, where otherwise your fan duct will be exposed to cold attic air in winter, use insulated solid metal ducting or insulated flex duct.
We insulate the bath vent ductwork to minimize the condensation that will otherwise occur as warm moist bathroom exhaust air passes through cool ductwork in the building attic or roof cavity.
Our photo shows a long routing of bath vent fan ducts across an attic floor to an exit at the building soffit or eaves and the condensation of moisture in such vent lines.
These ducts should be insulated (or replaced with pre-fab insulated ductwork or flexduct), and a better installation would have shortened that very long duct as much as possible, exiting to a soffit closer to the bathroom.
Above we illustrate bath exhaust vent ducting before and after it is covered by a spray foam insulation job in a cathedral ceiling.
Watch out: we do not recommend purchasing vent ducts with insulation on the duct interior. Although fiberglass-lined HVAC ducts are widely used in heating and air conditioning systems as well as in heat recovery ventilator systems, for a standard bath exhaust fan vent duct, the combination of permeable fiberglass or other insulating material and very high moisture levels is asking for mold or other trouble inside the vent line.
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Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: firstname.lastname@example.org or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
"Panasonic® Ventilating Fan Installation Instructions, FV-05VQ3, FV-08VQ3, FV11VQ3, FV-15VQ3", X120-4-8189Panasonic Consumer Electronics Co., Div. of Panasonic Corp. of North America, One Panasonic Way, Seacaucus NJ 07094 & Panasonic Canada, Inc., 5770 Ambler Dr., Imssissauga, ON L4W 2T3, Website: www.panasonic.com, retrieved 4/7/14
"Brink Renovent HR Installation and Operation Manual", Brink Climate Systems, P.O. box 11
NL-7950 AA Staphorst
+31 522 46 99 44
www.brinkclimatesystems.nl retrieved 4/7/14 This is the installation guide for medium & large Brink Renovent HR systems.
"Installation Instruction, Heat Recovery Unit, Renovent Small", Brink Climate Systems, P.O. box 11
NL-7950 AA Staphorst
+31 522 46 99 44
www.brinkclimatesystems.nl retrieved 4/7/14 This is the installation guide for the small Brink Renovent HR system. [copy on file]
"About the House - Bathroom Vents", Henri deMarne, New England Builder, November 1985
"Bathroom Vent Fan Beats Open Window", James Dulley, Poughkeepsie Journal, 11/4/1987 p. 12D.
References for Bathroom Vent Fan Installation
Fantech Installation, Operation, and Maintenance Manual, PB Series Premium Bath Fans. These fan models use a remote fan motor and
are available in 4" duct and 6" duct models. Web search 7/26/11 - original source http://fantech.net/docs-resi/412889-pb-install.pdf
Fantech in the United States
10048 Industrial Blvd.,
Lenexa, KS 66215
Phone: 800.747.1762; 913.752.6000
Fax: 800.487.9915; 913.752.6466
Fantech in Canada
50 Kanalflakt Way,
Bouctouche, NB E4S 3M5
Phone: 800.565.3548; 506.743.9500
Fax: 877.747.8116; 506.743.9600
Nutone Bathroom Exhaust Fan/Light Combination Installation Instructions, Model 8663RP, 8673RP, 8664RP suitable for use
in shower or tub enclosure when used with GFCI protected branch circuit. Suitable for use in insulated ceilings.
Nutone, 4820 Red Bank Road, Cincinnati, Ohio 45227, web search 07/27/2011, original source:
"Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
"Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
"Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
"Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
"Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
Humidity: What indoor humidity should we maintain in order to avoid a mold problem?
Re-Bath, tub lining products is a bath tub relining manufacturer and distributor located in Tempe, Arizona - see rebath.com
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The HOME REFERENCE BOOK - the ENCYCLOPEDIA of HOMES, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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