Frequently Asked Questions - Residential Testing Application | Retrotec

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What is the flow range (in units of CFM) for the 5000/6000 fan's range configurations?

Answer

500 Flow Chart.

6000 flowchart

Why does my gauge show two dashes “—“?

Answer

​Fan Pressure (flow pressure) is too low for the Range, which means you should change to a smaller more restrictive Range to increase fan pressure.

Can I control my DM32 over Ethernet and still plug the DM32 USB into a computer for power?

Answer

In order to do both, you need to be sure you have version 5.8.30 of FanTestic or later.

In all versions of FanTestic before version 5.8.30, if you plugged a DM32 into a computer USB to give it power (instead of plugging into the wall adapter) FanTestic would assume you also wanted to use USB Serial connection for control. FanTestic made this assumption even if the gauge was also connected to the computer over Ethernet (via the Network cable or via WiFi).

In all versions starting with 5.8.30, FanTestic discovers gauges connected via Ethernet first, so it can ignore the same...

Where do I place the exterior pressure pickup tubes?

Answer

The exterior pressure reference for the differential pressure measurement across the door panel is provided by the red tube. The exterior pickup location must be chosen to minimize the influence of wind, sun and atmospheric pressure on the differential measurement, or measurements must be taken to allow correction for these influences. Each standard defines what is expected in terms of the exterior reference pressure measurement. Use Table 2 to determine where best to locate your red tube depending on the standard procedure you are following.

Table 2: Locations for Exterior...

Should I be concerned with air leakage into an attached garage?

Answer

The big issue is exhaust getting into the house. Duct leaks from the supply side cause the house to have a negative pressure, which can cause air to get pulled in from the garage. Exhaust entering the home can be dangerous and can lead to health issues.

The first step is to find what the maximum house depressurization would be with combinations of the airhandler on, closed bedroom doors, and any exhaust fans running. Do what you can to eliminate these pressures. Check to make sure there aren't any air intakes (returns) inside the garage.

To determine how leaky the garage to...

My duct test using DW/143 is not compliant, what am I doing wrong?

Answer

FanTestic checks that you have held the ducts at the test pressure for at least 900 seconds. If you do not, the test will show as not compliant. If you did a manual test and are entering the information into FanTestic, be sure to enter the time over which the test pressure was held. If this is greater than 900 and your other test conditions are correct, the test will show compliant.

Compliance means the test conditions comply with the stated requirements for a test in DW/143. Pass or fail means that the measured results are within the required level.

Is using a positive duct test pressure advantageous?

Answer

The main disadvantage to positive duct test pressure is that it blows off register seals or makes them leak. An LBL study showed a wide dispersion of results when the same duct test was repeated many times. Depressurizing will allow the use of lower sticking masking materials that are less likely to pull off the paint. In some cases plastic food wrap will work.

The main advantage to positive duct test pressure is that the flex duct doesn't contract as much. In cases where the flex runs to the ceiling this contraction effect might cause problems.

Testing using...

I have pinholes in my Model 240 or 340 DucTester flex ducts.

Answer

​One question we get a lot is about leaking flex duct that connects the ducTester to the return. We have tested the most ripped up flex available in our warehouse; it had way bigger pinholes and it measured 0.68 CFM at 25 Pa. When you measure a typical leakage of 100 CFM at 25 Pa or more, this is not even 1%. So we believe it is not worth spending money on replacing.

How do I know how many fans I need for a Blower Door or Enclosure Integrity Test?

Answer

We have created two tools to help you ​figure out how many fans you will need for your test.

To access them, click on the link below:

http://retrotec.com/support/software-downloads

Then, scoll down to the Tester Tools section and download either the Blower Door or Enclosure Integrity version of the Number of Fans Calculator .

Next, open the file in excel and "Enable Editing" when a security warning appears.

Fill in...

When should I care about leakage around the door panel?

Answer

Modular Panels are designed to be placed into doors that are not well sealed. The panel leakage for the Modular Panel is about 14 square inches compared to about 3 square inches for the Aluminum Frame and Cloth and around 1 square inch of leakage for the upgraded Aluminum Frame with snap together corners. These three panels represent three typical doorways:

  1. Poorly weather-stripped which would have an approximate 1/16 inch gap which equals about 14 square inches leakage;
  2. A well weather-stripped and adjusted door would be around 3 square inches or leakage;
  3. A
  4. ...