Retrotec Blower Door - Manual (Page 15)

Retrotec Inc.
1.5 A Fan Speed Controller sets the test pressure
If operating the Blower Door Fan System manually, a knob on the fan or a Manual Speed Control accessory allows
the speed of a fan to be controlled by turning a knob/dial. Otherwise, speed can be controlled from the DM-2 or
DM32 gauge.
The gauge can operate as a fan speed controller in addition to being a two channel differential pressure gauge. In its
role as a fan speed controller, the gauge is connected to the fan through an electrical control connector and changes
the speed of the fan until the pressure difference across the doorway reaches the desired test condition.
For instructions on connecting and operating each controller, see section 1.5.1 for the Fan Top speed control,
section 1.5.3 for the Manual Speed Control accessory, and section 1.5.2 to operate the gauge speed control
function.
The Fan Speed Control output on the gauge speed control cable which connects to the fan uses RS-485 protocol.
This protocol allows the Speed Control Cable to extend approximately 1,200 metres (4,000 feet) between the gauge
and the fan.
A speed control splitter can be used to control more than one fan with a single gauge, see section 1.5.4.
1.5.1. Use Speed Control Knob on the fan
Some fans provide a Speed Control Knob on the Fan Top which allows the user to manually control the speed of the
fan.
To use the Manual Speed Control Knob
1. Set the fan speed to zero by adjusting the Speed
Control Knob as far as it will go, counter clockwise.
2. Turn the Door Fan power on.
3. Slowly adjust the knob clock-wise, to accelerate
the fan.
1.5.2. Control fan speed with a DM-2 gauge
To control the fan speed with a DM-2
1. Connect the included Speed Control Cable from the Fan Top to the port on the back of the DM-2 (labeled
“Speed Control”). The cable provided by Retrotec is specially wired to prevent interference between the fan
and gauge, but if unavailable, any standard CAT5 or CAT6, Ethernet-style cable can be used.
1. Some fans have more than one speed control port on the Fan Top. In these cases, additional Speed Control
Cables can be used to link multiple fans together, with the primary fan being connected to the DM-2. This
will allow one gauge to control the fan speed of all fans in a chain, called “daisy-chaining the fans”.
2. If the battery power is too low, connect the DM-2 power cable (in the Umbilical) from the power outlet on
the Fan Top to the power input on the gauge. Some model fans do not have this option, in which case the
DM-2 would have to be connected to a power outlet using the provided power adaptor.
1.5.3. Use a Manual Speed Control accessory
Figure 6: Speed Control Knobs on the Fan Tops of Door Fans. The Speed
Control Knob of the 2350 Door Fan is displayed on the left, and of the 1000
Door Fan on the right.