Temperature, initial, Baseline/bias pressure, initial [pa, Time per induced pressure – Retrotec FanTestic (ATTMA) User Manual
Page 35: 7 temperature, initial, 8 baseline/bias pressure, initial [pa, 9 time per induced pressure
rev-2014-10-27
Page 35 of 58
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determine the test direction (Pressurization or Depressurization). The test direction will be displayed
beside the Start time:
5.7 Temperature, initial
Enter the indoor and outdoor temperature at the start of the test. The initial temperature is to be
entered before both the pressurization and depressurization sets.
5.8 Baseline/bias pressure, initial [Pa]
This is the baseline pressure before a pressurization or depressurization test. Baseline values are
averaged to correct the building gauge pressure readings. Once the building is prepared for the test but
before turning on the fan, determine the baseline pressures.
According to the ATTMA standard, at least 10 bias pressure readings (taken with measurements
averaged over 10 seconds) are required before the test starts. Values can be measured and entered
manually by using the [Baseline] function on the Retrotec gauge, or let the automatic test capture them.
When manually entering data into FanTestic, set the time averaging on the gauge to at least 60 seconds
for baseline readings. This must be done in order to compensate for the effects of wind and to ensure
that you get an average reading. On windy days you will have to take readings for a longer period of
time. To determine if it is windy, set your gauge 25 second averaging and if the pressure fluctuation is
above 2 Pa. If so, double the time averaging for the baseline to 120 seconds.
On the DM32, tap Channel A to activate the Hold feature so the readings don’t change while you’re
writing them down.
FanTestic calculates the average initial baseline and reports it in the Data set. Initial and final baseline
values are averaged and used to correct the building gauge pressure readings.
P01 = average of all pre-test Baseline pressures
P01- = average of negative pre-test Baseline pressures
P01+ = average of positive pre-test Baseline pressures
Note that P01- can be zero if there are no negative Baseline pressures in your data.
5.9 Time per Induced Pressure
The Time per Induced Pressure must be greater than 20 seconds to comply with ATTMA.