dB AM Series, Installation, Operation & Maintenance Instructions Manual

Page: 8 / 16

8
Fan Speed Adjustment (EC Motors)
1. Heaters fitted with EC motors are available
as one of two standard options:-
ECS - variable fan speed with speed control
by an external 2-10VDC signal (e.g.
from BMS)
ECM - single or dual fan speed with speed
control using switches or thermostats
via a fitted speed interface.
2. In the unlikely event that fan speeds require
adjustment, refer to the wiring diagram
supplied with the heater. Contact Dunham-
Bush for guidance on adjusting fan speeds
and selecting appropriate DC signal voltages.
3. The ECM speed controller is located
underneath the fan/motor platform and
comprises electronic controls with inputs
from thermostats and/or switches and a
single analogue 2-12VDC output signal to
the motor(s).
4. Refer to Diagram 9; three fan speeds are
available. Single speed heaters will use one
speed and dual speed heaters will use two
speeds, which can be varied by adjusting the
appropriate potentiometers; signal voltage can
be measured across 0V and CTRL terminals.
5.
Avoid setting fan speeds too low:-
a) low fan speeds can cause stratification of
heated air within the room, reducing
effective comfort
b) low fan speeds with electric heating can
cause false tripping of high-temperature
safety cut-outs in the heater.
6. All connections to the EC fan controller shown
in Diagram 9 are safe low voltage of 10VDC
or less.
Diagram 9: Fan speed interface with 3 speeds
(ECM fan motor option only)
Size
Low speed Medium speed High speed
Fan
voltage
(VDC)
Airflow
(l/s)
Running
current
(A)
SFP
(W/l/s)
Fan
voltage
(VDC)
Airflow
(l/s)
Running
current
(A)
SFP
(W/l/s)
Fan
voltage
(VDC)
Airflow
(l/s)
Running
current
(A)
SFP
(W/l/s)
Fig 3 3.4 50 0.08 0.16 4.6 75 0.14 0.19 6.2 110 0.26 0.26
Fig 4 3.5 75 0.10 0.13 5.5 110 0.20 0.20 7.5 150 0.40 0.30
Fig 6 5.2 105 0.18 0.19 7.5 150 0.40 0.30 8.8 175 0.54 0.38
Fig 8 3.4 130 0.16 0.12 5.8 220 0.40 0.21 7.1 275 0.64 0.27
Fig 10 5.4 205 0.35 0.19 7.0 270 0.64 0.27 7.7 290 0.77 0.31
Fig 12 4.4 210 0.30 0.16 5.8 280 0.54 0.22 7.0 350 0.82 0.27
Fig 15 5.8 280 0.54 0.22 6.7 330 0.60 0.21 7.0 350 0.82 0.27
Table 3: Electrical data for EC motors (ECM motor options only; data for ECS motor option will vary)
Optional Panel Lock Indicators
Colour indicators show whether an access panel is
locked or unlocked. The lock position is shown
through the 10mm viewing window next to the lock;
green indicates the panel is safely locked and
cannot be removed or fall out; red indicates that the
access panel is unlocked.
Lock indicators can be retro-fitted to all Series AM
models by replacing the standard access panel with
a new one which includes the lock indicators. For
panel lock indicators, refer to Dunham-Bush, stating
part numbers reference 21-253-208. Price and
delivery upon application.
Diagram 10: Lock indicator green – panel locked Diagram 11: Lock indicator red – panel unlocked