Retrotec Blower Door - Manual (Page 38)

Page 38 of 87
©Retrotec Inc. 2015
If the enclosure to be measured has an excessive amount of leakage, to the point where a single fan unit on the
Open Range and at maximum speed, cannot reach the required pressure, try one of the following solutions:
1. Use a second (additional) fan to produce more flow. The combined flow readings can be used to get the total
amount of airflow required to achieve the induced pressure. Do not add Fan Pressure readings (PrB), they are not
cumulative. Fan Pressure must be converted to flow in CFM (or some other units) and then the resulting flows can
be added together.
2. Test at the highest pressure that can be reached, and use the @ Pressure key to extrapolate what the flow would
be at the desired pressure. Check that the Standard you have to comply with allows this.
3. Seal leaks prior to testing. This can include ensuring that all dampers, windows, and doors are closed, in addition
to sealing leaks and holes. This may reduce the leakage enough that the desired test pressure can be reached.
4.11 Choose either a Single or Multi- Point Test Procedure
There are two common Door Fan test procedures available for testing the air leakage of a building: a single-point test,
and a multi-point test.
A single-point test establishes a 50 Pa test pressure in the building; results come from measuring the fan flow required
to maintain the pressure imbalance. This is a quick and simple way of measuring airtightness, and by using the Fan
Pressure measurement, simple results such as the size of the total leakage can be determined.
A multi-point test requires that the user collect flow data for several different induced target pressure points.
4.12 Taking Manual Single Point Readings
This section is written for circumstances where results are read directly from the gauge. They may possibly be recorded
manually also but not necessarily.
4.12.1. Measure the Baseline Pressure before turning the fan on
Commonly, test procedures require that the pre-existing pressure across the building be measured and that value be
subtracted from the test pressure to uncover how much change occurred in the building pressure due to Test Fan
operation. Baseline is sometimes called Bias Pressure or even Static Pressure but we will primarily use “Baseline”
here.
The length of time to take the Baseline varies from Standard to Standard or the amount of time needed may not be
mentioned. Ten seconds is a reasonable amount of time to spend on Baseline Capture on a calm day but as the wind
increases or the Baseline fluctuates at all, this should be increased. To determine the effects of wind, set your gauge
to 1 second averaging and if the pressure fluctuation is above 1 Pa, take the Baseline for 30 seconds. If the pressure
fluctuation is above 2 Pa, take the Baseline for 120 seconds. If the fluctuation is still above 1 Pa after 120 seconds,
continue to acquire the Baseline until the average fluctuates less than 1 Pa.
Save this Baseline once you are satisfied with it. The value stored and displayed on your gauge will be deducted
from all future readings so make sure you eliminate the stored Baseline before running your gauge in another
application.
4.12.2. Adjust your test fan manually
Adjust the Blower Door (also called Test Fan or Door Fan) fan speed manually using the control knob to the required
test pressure that will often be 50 Pa. Change the Range if you cannot achieve the test pressure or if no flow reading
appears on Channel B. With the gauge still set to a Time Averaging of 1 second, you may take a reading but chances
are you’ll be over or under the required test pressure or the result will fluctuate on either side. To get the exact