Your browser is not supported. For the best experience, you should upgrade to a modern browser with improved speed and security.
Click here for our 2017 Spring Training Calendar

Thermaflex® 12" RKD R4.2 Flex-Vent Insulated Flexible Air Duct (Box)

Item: FD-12X25-R42MH
MFR: 056512000001

Store Inventory

Sign in to see real-time inventory at the stores closest to you.
Equipment part list is available.
What’s the price?
Sign in for pricing.
Decrease quantity
Increase quantity


Thermaflex® R-KD duct is a thermally insulated, fully lined, UL 181 Class I flexible air duct designed for efficient installation and operation in outdoor cooling and heating systems of low and medium pressure. It is available in standard 25-foot lengths.
Because of its extreme flexibility and good weathering characteristics,Thermaflex® R-KD is particularly suitable for add-on mobile home remote air conditioning, for connecting double wide units as crossover duct, and for use in modular building systems.
Thermaflex RK-D complies with HUD Mobile Home Constructionand Safety Code Part 3280.715, Chapter II of 24 CFR.
It provides an economical means for handling misalignment between system components and ducting around obstacles where fabricated and fitted ducts are difficult and costly to install.


Weight17.3 Pound (lb.)
Width12 Inches (in)
Height15.125 Inches (in)
Country of OriginUSA
UPC or Barcode677431004367
Hazardous MaterialNo
EPA Cert RequiredNo
Length15.125 Inches (in)
ApplicationAir Distribution
Comments/NotesUL Listed - USA & CAN
ComplianceNFPA 90 A and 90 B
CompositionLaminated Polyester duct liner is permanently bonded to a corrosion-resistan spring steel wire helix. Also supporting a thick blanket of fiberglass insulation and fiberglass scrim vapor barrier is an outer jacket of heavy Black polyethylene.
Core MaterialPolyester Film
Fire RatingMeets UL 181 & NFPA 90A-90B Fire Codes
Inside Diameter12"
Jacket MaterialVapor Barrior
Maximum Air Flow5000 FPM
Maximum PressurePositive = 6" (6-14" ID) Negative = 1" (6-12" ID) 1/2" (14" ID)
Maximum Temperature250°F (121.1°C)
Operating Temperature-20°F to 250°F (-28.8°C to 121.1°C)
Pressure RatingWG - Positive 6 inches (18"-20" ID) - Negative 1/2 inch (6"-12" ID)
TierR-KD Flexible Air Duct
UL ListedYes
UL RecognizedYes
Vapor Transmission0.1
Warranty Offered10 Year Parts

Equipment Part List

Shop all compressors