Depressurization Test Procedures Using the DG-3

The following test procedures cover use of the DG-3 for both One-Point Tests and Multi-Point Tests.

a) Turn on the DG-3 and put it into the proper Mode (same for both One-Point and Multi-Point Tests).

Turn the CHANNEL knob to A, turn the MODE switch to Pressure, and put the RANGE switch in the Low Range position (200.0 Pa).

b) Measure the baseline building pressure (same for both One-Point and Multi-Point Tests).

When conducting a Blower Door test, we want to measure the change in building pressure caused by air flowing through the Blower Door fan. In order to measure this change accurately, we need to account for any existing pressures on the building caused by stack, wind and other driving forces. This existing building pressure is called the "baseline building pressure".

Chapter 5 Conducting a Blower Door Depressurization Test

When using the DG-3 gauge, we need to measure and record the actual baseline building pressure (see

Appendix D for a sample test recording form). Baseline building pressure is read from Channel A of the gauge.

With the fan sealed off, record the baseline building pressure on a Test Form, including the sign of the reading (i.e. negative or positive reading). If the pressure is fluctuating too much to determine the reading, try changing the Time Averaging setting on the gauge by turning the Mode Switch to Time Select, choosing the 5 or 10 second or Long-term average, and then return the Mode Switch to the Pressure setting.

Note: If you will be using the TECTITE software, the measured baseline building pressure will need to be entered into the program's Data Table.

c) Choose a Flow Ring for the Blower Door fan (same for both One-Point and Multi-Point Tests).

Remove the No-Flow Plate and install the Flow Ring which you think best matches the needed fan flow. Installation of Flow Rings will depend on the tightness level of the building stock being tested.

For example, for relatively leaky buildings (greater than 3,000 CFM50), you will want to start the test using the Open Fan configuration (i.e. no Flow Rings installed). As you test tighter

buildings, you will need to install Flow Rings A or B. Refer to the Table to the right for approximate flow ranges of the fan using the various Flow Rings configurations. Don't worry if you guess wrong and start the test with the incorrect Flow Ring - you can change the Fan Configuration during the test procedure.

d) Enter the selected Flow Ring into the Gauge (same for both One-Point and Multi-Point Tests).

In order for the DG-3 to properly display fan flow, you need to input the Blower Door fan model and selected Flow Ring into the gauge. To select the fan type and fan configuration being used in your test, first turn the MODE knob to the Fan Select position. The gauge display will show "-SEL" to indicate that a fan type and fan configuration have not yet been selected. The fan type can be selected by toggling the SELECT Switch up. The fan configuration can be selected by toggling the SELECT switch down.

If the Display

Shows Description

-SEL Begin fan type selection by toggling the SELECT switch up once.

3-0 This indicates that you have chosen the Model 3 Minneapolis Blower Door fan, and that the fan is in the "Open" inlet configuration (i.e. no Flow Rings installed).

To change the fan inlet configuration for the Model 3 Blower Door fan, toggle the SELECT switch down.

To change the fan type to the Model 4 Blower Door fan, toggle the SELECT switch up twice (DG-3E gauge only).

4-0 This indicates that you have chosen the Model 4 Minneapolis Blower Door fan, and that the fan is in the "Open" inlet configuration (i.e. no Flow Rings installed).

To change the fan inlet configuration for the Model 4 Blower Door fan, toggle the SELECT switch down.

Fan Configuration Flow Range (cfm) for Model 3 Fan Open (no Flow Ring) 6,300 - 2,430 Ring A 2,800 - 915 Ring B 1,100 - 300 Ring C 330 - 85

Chapter 5 Conducting a Blower Door Depressurization Test

Once you have input the fan configuration, turn the MODE knob back to Pressure, and then flip the RANGE switch to the 2000 setting (High Range).

e) Turn on the fan for an initial inspection (same for both One-Point and Multi-Point Tests).

With the CHANNEL knob set to Channel A, turn on the Blower Door fan by slowly turning the fan controller clockwise. As the fan speed increases, building pressure indicated on Channel A should also increase. As you increase the fan speed, you will be increasing the pressure difference between the building and outside resulting in increased pressure exerted on the aluminum door frame installed in the door opening. If you did not properly install the door frame, the frame may pop out of the doorway at higher building pressures (over 30 Pascals). If this happens, simply reinstall the frame more securely. When installed properly, the frame will easily stay in place during the entire test procedure. Before making measurements, you may want to quickly walk around the building with the fan producing about 30 Pascals of building pressure to check for any problems such as windows or doors blown open or blowing ashes from a fire place or wood stove.

f) Make final adjustments to the Blower Door fan:

• DG-3: One-Point Test

Increase fan speed until the building is depressurized by 50 Pascals from the baseline pressure measured in section b) above (i.e. change the building pressure by 50 Pa from the baseline building pressure). In order to do this, you first need to calculate a new adjusted target test pressure to shoot for. This is done by manually adding the measured baseline building pressure to the target depressurization.

Example: If the measured building baseline pressure was negative 2 Pascals (-2 Pa), the new target test pressure becomes (-2 + (-50)) or -52. In other words, you will need to depressurize the building to -52 Pascals for your One-Point Test. The main point to remember is that we want to change building pressure by 50 Pascals from the starting point (baseline) pressure.

Note: If you are using the DG-3 and the TECTITE software program, it is not necessary to adjust the target pressure of -50 Pascals for your One-Point Test because the baseline building pressure can simply be entered into the TECTITE Data Table.

After adjusting the fan speed to depressurize the building by 50 Pascals, turn the CHANNEL knob to Channel B, and turn the MODE switch to Flow. The gauge will now display the One-Point CFM50 leakage result for the building. If the gauge display is fluctuating too much to determine the reading, try changing the Time Averaging setting on the gauge by turning the MODE Switch to Time Select, choosing the 5 or 10 second or Long-term average, and then returning to the Flow mode. Record the CFM50 test reading on a Test Form (see Appendix D). Turn off the fan.

(If the CFM flow reading on Channel B is blinking, see below):

- The CFM flow reading on Channel B will blink when the air flow reading through the fan is unreliable (i.e. you are trying to measure a flow outside of the calibrated range of the test device in its current configuration). If possible, you should change the fan configuration to match the flow rate being measured (e.g. install a Flow Ring or a smaller Flow Ring).

- If you change Flow Rings, be sure to use the Fan Select feature to update the gauge with the new Flow Ring installed before reconducting the test.

Chapter 5 Conducting a Blower Door Depressurization Test

• DG-3: Multi-Point Test

Increase the fan speed until you achieve the highest target building pressure (e.g. -60 Pascals) on Channel A.

Now determine the air flow through the fan needed to create this building pressure by first turning the

CHANNEL switch to Channel B, and then turning the MODE knob to the Flow position. The gauge will now display the flow through the fan. Record the test readings (building pressure and fan flow) on a Test Form (see Appendix D).

Turn the CHANNEL switch back to Channel A and then turn the MODE knob back to the Pressure setting.

Now reduce the fan speed until the building pressure equals the next target pressure (e.g. -50 Pa). Once again determine the air flow from Channel B and record the test readings on a Test Form. Continue this procedure for each of the remaining target pressures. Turn off the fan when the final set of readings are completed.

Enter the test readings into the TECTITE software to generate your final test results.

(If the CFM flow reading on Channel B is blinking, see below):

- The CFM flow reading on Channel B will blink when the air flow reading through the fan is unreliable (i.e. you are trying to measure a flow outside of the calibrated range of the test device in its current configuration). If possible, you should change the fan configuration to match the flow rate being measured (e.g. install a Flow Ring or a smaller Flow Ring).

- If you change Flow Rings, be sure to use the Fan Select feature to update the gauge with the new Flow Ring installed before reconducting the test.