Retrotec 340x Residential DucTester User Guide
- October 30, 2023
- retrotec
Table of Contents
Retrotec 340x Residential DucTester
Retrotec’s Model 340x
Residential DucTester Quick Guide
Unpack, connect gauge
Prepare the DMB2X
Prepare the ducts and hous
- Turn off air-handlers or adjust temperature so the unit will not turn on.
- If a whole-house ventilation system is present, be sure this is set to off as well.
- Remove all air filters
- Seal supply and return grills/registers, including any exterior air inlets, with Grill Mask, plugs, covers, or tape.
- Open interior doors leading to rooms containing a supply or return register.
- Open an exterior door or window
- See “Residential Duct Testing Manual” for additional information.
Connect to ducts
Attach the Flange to main return or air handler cabinet. Ensure filter has
been removed,
- Attach Flex Duct to the collar on the Flange
- Install Range Plug 74 to start, as most systems can be tested on this Range Configuration.
- Connect Flex Duct to fan inlet The negative pressure will improve the seals at the registers.
- If Codes require you to pressurize, pass the test in the depressurize direction first, then connect the Flex Duct to fan exhaust in order to pressurize. All other connections remain the same.
Use smaller Range number for tighter ducts, and larger number for leakier
- Tap the image of the DucTester on the gauge and select the range to match your fan whenever a Range plug is changed.
Connect Flex Duct to fan inlet. The negative pressure will improve the seals at the registers.
Connect gauge & fan
- Plug in the power adapter. Blue light indicates that the power is connected.
- Connect yellow and green tubes to matching color ports on the fan.
- Connect the Speed Control Cable to allow the gauge to control the speed. A solid green status light indicates gauge is ready to control the speed.
- Insert blue tube into the supply register closest to the air handler. Use the static pressure probe attachment to reduce readings from velocity pressure.
Total Duct Leakage Test: Depressurize Ready to conduct the test by
depressurizing the ducts:
Conduct test
- Connect the Speed Control Cable to allow the gauge to control the speed. A solid green status light indicates gauge is ready to control the speed.
- For a test pressure of 80 Pa, tap [Set Pressure], enter 80, and tap [Set].
- If you cannot achieve the test pressure, refer to the instructions below under “Desired Results Not Achieved?
- Tap display what the result would be at exactly 25 Pa.
- Read results directly from the gauge.
Get the results you need
Tap [Channel B] on the screen to select a different Result, or tap the [Result
to be displayed] button in the [Settings] menu.
- Flow in CFM is the simplest result.
- Flow / Area (Flow per area) in CFM per square foot may be required in some cases. Make sure to enter the required Area.
- Flow / Area (Flow per area) in CFM per 100 square feet is the most common code requirement. Make sure to enter the required When a Result is chosen that requires a Area or Volume, Area or Volume will be shown on the Home Screen. Tap to Change.
Show leakage area Result
Equivalent Leakage Area (EqLA) describes the leakage area in terms of one large hole in a flat surface.
- Tap the [Channel B] key and select “EqLA: sq in.”
- [Channel A] shows the duct pressure.
- [Channel B] “EqLA” shows the combined size of all the holes in the ducts.
Leakage area is not a required result, but is a nice way to visualize the size of the hole in the ducts.
Desired results not achieved?
Flow reads “- ” at test pressure?
If the test pressure has been reached, but “- ” appears, the fan is running
too slowly to accurately measure flow.
- Switch to a lower Rang Plug.
- [Change Range] on the gauge to match.
- Re-adjust fan speed.
If fan reaches 100% speed before reaching 25 Pa:
- Change to a larger Range Plug and try again.
- Change [Range] on the gauge to match.
- Check seals on all registers. Look for disconnected ducts or ducts open to outdoors.
- Tap Pressure] to get the gauge to calculate what the flow would be at exactly 25 Pa.
Field check gauge weekly
Check for gauge accuracy, blocked, leaking, or pinched tubes weekly, and
anytime results are in question.
- Check the gauge with the tubes in the Umbilical.
- Set [Time Average] to 5 seconds in [Settings]
- Tap [Channel 3] and select “Pressure: Pan
- Connect the red tube between the red and yellow ports. If readings on Channel A and Channel B are within 2% and don’t drop noticeably in 5 seconds, the gauge is functioning correctly.
- Remove red tubes and repeat with the yellow tube between the blue and green ports.
Theatrical Smoke
Theatrical smoke can help detect suspected leaks while the DucTester is
running. See manual for details. Caution: Do not inject the smoke directly
into the fan motor, but instead inject it into the flex duct just after the
fan. Injecting the smoke directly into the fan motor will void warranty.
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