Armstrong Design Envelope 4380 - Control Modes and Pump Configuration; Control Modes Overview; Basic Control Modes

installation &
operating instructions
Design Envelope 4300 & 4380 Vertical
In-line pumping unit with ivs drive
45
5.0 control modes
5.1 constant flow
Design Envelope pumps can be configured to maintain a
constant pump flow in a system as the system head varies.
This eectively simulates speed control by a flow meter in
the piping.
0
0
20 40 60 80 100
200
400
600
800
1000
1200
120 140 160 180
head
flow
target curve
Constant Flow Control Curve
5.2 constant pressure
Design Envelope pumps can be configured to maintain a
constant pump head in a system as the demand varies. This
eectively simulates the mounting of a dierential pressure
sensor at, or near, the pump.
0
0
20 40 60 80 100
200
400
600
800
1000
1200
120 140 160 180
head
flow
target curve
Constant Pressure Control Curve
5.3 linear pressure
Linear Pressure Control is where the controller is set to
control the speed according to a control ‘curve’ between
max and min flow. This type of control will change the pump
speed to ensure the pump operates on the projected linear
control curve, where the pump head varies directly with
the flow. This type of control is well known globally and is
eective as far as the straight linear line will allow. For more
realistic hvac control with superior energy savings, consider
the following control recommendation 5.4 Quadratic Curve
Control.
0
0
20 40 60 80 100
200
400
600
800
1000
1200
120 140 160 180
head
flow
target curve
Linear Pressure Control Curve
5.4 quadratic curve control
Quadratic Pressure Control is where the controller is set to
control the speed according to a control curve between max
and min flow. It is widely recognized that fitting a dierential
pressure sensor at the most remote load, across the supply
piping and return piping encompassing the valve and coil set,
is the benchmark scheme for energy eciency.
Design Envelope pumps can replicate this control without
the need for the remote sensor. As the flow required by the
system is reduced, the pump automatically reduces the head
developed according to the pre-set control curve.
0
0
20 40 60 80 100
200
400
600
800
1000
1200
120 140 160 180
head
flow
target curve
Quadratic Control Curve
5.5 quadratic curve control with
minimum flow protection
This configuration is designed for hvac hydronic systems
where flow sensitive equipment required a minimum flow for
equipment stability; such as a chiller that cannot tolerate flow
below a certain volume. This control will take advantage of
the 5.4 Quadratic Curve Control mode, where the pump will
increase speed to maintain a minimum flow setting as the
system load is shutting down.
Pump controls can only control the flow to the maximum
speed or motor limit;
0
0
20 40 60 80 100
200
400
600
800
1000
1200
120 140 160 180
head
flow
target curve
Minimum Flow Setting
5.6 quadratic curve control with
maximum flow protection
This configuration is ideal for hvac hydronic systems where
pumps are generally oversized and a flow limit is required
for system equipment stability and resulting energy savings.
This control will take advantage of the 5.4 Quadratic Curve
Control mode, where the pump will decrease speed to main-
tain a maximum flow setting. This will prevent over-pumping
and save energy costs. Over-pumping is common in hvac
systems as pumps are typically oversized for the application.
Pump controls can only control the flow to a minimum speed;