Retrotec 4" DucTester Range Plugs — Range 74, 47, 29 (US340x) & 18, 11 (400 Series)

Tight ducts need a smaller hole. Retrotec's 4" (10 cm) range plugs restrict the DucTester fan inlet so it can measure low airflow accurately. When...
$ 80.00
$ 80.00
Range: Range 29 (RP029) – US340x

Tight ducts need a smaller hole. Retrotec's 4" (10 cm) range plugs restrict the DucTester fan inlet so it can measure low airflow accurately. When a duct system is too tight for your current plug, the gauge shows "--" instead of a number. The right range plug turns that dash into a passing result.

Genuine Retrotec parts. Push-in fit, durable, nothing to adjust. Check the fan series before you order: Range 74, 47 and 29 fit the residential US340x (300-series fan). Range 18 and 11 are for Retrotec's 400-series commercial DucTesters (US440x / US450x).

Which range plug do I need?

Range plug Part # Fits Best for
Range 74 RP074 US340x (standard in kit) Most systems: start here
Range 47 RP047 US340x (standard in kit) Typical new construction
Range 29 RP029 US340x (optional add-on) Tight ducts, small systems
Range 18 RP018 400-series commercial (US440x / US450x) Tighter systems on commercial DucTesters
Range 11 RP011 400-series commercial (US440x / US450x) Very low flows on commercial DucTesters

Not sure which fan you have? The model number is on the fan label, or call (512) 650-VENT and we'll confirm before you order.

How to pick the right range in the field

  • Start on Range 74. Most duct systems test on it.
  • Gauge shows "--" at test pressure? The fan is turning too slowly to measure. Step down to a smaller range number.
  • Fan hits 100% before reaching test pressure? Step up to a larger range number.
  • Every time you swap plugs, change the Range setting on your DM32X gauge to match, or the flow reading will be wrong.

Your US340x ships with Range 74 and 47. If you're testing new homes built to modern code, multifamily units or small systems, Range 29 is the plug most raters add first.

Details

  • Genuine Retrotec part, sold individually
  • 4" (10 cm) diameter
  • Ships direct from Retrotec
  • Questions about fit or which range you need? Call (512) 650-VENT.

Make setup as fast as the test. Seal supply registers in seconds with Vent Caps, and the return grille with the Duct Ninja. No ladder, no tape.

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