Retrotec Multi-Fan Blower Door - Manual (Page 15)

Page 15 of 37
©Retrotec Inc. 2015
5. Multiple Fan Testing Scenarios
The following are different scenarios that illustrate multi-fan testing problems, solutions to them, and
how to choose whether the Individual Control setting in FanTestic software should be On or Off.
Note that the diagrams in this section display the cable connections for a DM32 gauge, which are
different for a DM-2 gauge; For cable connections for a DM-2 gauge, refer to Manual-DM-2 Operation.
Also note that the diagrams show a Control Cable connected from the gauge directly to the fan for
simplicity, however if the fan is a high output fan (Retrotec 3000 series), the Control Cable will actually
be connected to the Drive of the fan instead.
5.1 One Zone, Multiple Fans:
Testing a single-zone enclosure can require multiple fans.
Problem 1: Imbalanced test fan flow caused by Individual set point control shown in Figure 12.
When more than one fan is individually set to control to the same pressure, the balance of flow between
the fans can shift so that some fans speed up which can cause others to slow down or stop altogether.
To utilize the flow capacities of all fans, a different method of fan control must then be used to ensure
the flow rates between the fans are balanced.
Figure 12: Problem1: Imbalanced test fan flow caused by Individual set point control
Solution 1: Use Common set point (“Individual Control” turned Off) which runs all fans at the same
speed.
To perform this with FanTestic, click Tools →Advanced Options → Settings tab → leave “Individual
Control” unchecked:
Common set point control has the same effect as using a Speed Control Splitter. The primary gauge will
receive a pressure target from FanTestic, and all other gauges will mimic the speed of the primary
gauge, as shown in Figure 13.
Target pressure: 50 Pa
50 Pa