Dexon Canada Air Systems Inc
OWMDH Series Use Manual
Version 07.2019
Page 5
3.2 FEATURES:
Overheat protection:
For Ordinary Location rated units one Klixon thermostat located at the
top of the element mounting panel will shut down the heating elements if temperature at the top
of the heat exchanger rises above approx. 65
°
C. For Hazardous Location rated units additional
thermostats on each element will cut power when the skin temperature of the elements reaches
approx. 107
°
C.
Low Temperature Shut Down:
When the sensor at the
discharge of the blower heater senses
temperature lower than 0°C (typically) the unit will go into a
“Low Temp.” shut down condition to
prevent freezing of the space. See sequence of operations for more information.
Discharge Temperature Sensor:
Monitors the discharge temperature to regulate the heating
elements to maintain a preset discharge temperature of b6°C to +18°C with an
adjustable 5° range (Example: A +6°C preset discharge temperature would be adjustable from
+5
°
C to +10
°
C and +15
°
C preset temp. would be adjustable from +13
°
c to +18
°
C).
Auto Reset:
The blower heater will automatically reset when temperatures reach +2
°
C
(typically)
after a “Low Temp.” shut down has occurred and after the elements have sufficiently
cooled from an “Overheat” condition.
Fan Boost Start:
Provides a momentary full output voltage to the fan for cold start-up etc.
Proof of Fan Rotation:
Provides an indication when the fan is no longer running and activates
remote alarms when the optional alarm module is included.
Staged Heating:
Staged heating is only provided for the larger SMDH/IMDH/WMDH/OWMDH
series and the SRVDH/IRVDH/WRVDH/OWRVDH series blower heaters to prevent high current
draw and reduce power consumption when not required. Stage 2 and Stage 3 heating elements
will only be used if Stage 1 is not able to maintain the preset discharge temperature setting and
only as required to maintain this discharge temperature.
CSA Certified:
Dexon blower heaters are CSA certified for Class 1, Div. 2, Gas Groups C & D,
Temp. Code T2C Locations and for Ordinary Locations. Any modifications to existing certified
units will require special CSA approvals/certification.
3.3 OPTIONS:
Various Installation Configurations:
The OWMDH series blower heaters are for outdoor,
through the wall applications with either back or bottom air outlets (See SMDH for outdoor
freestanding, WMDH series for indoor wall mounted and IMDH Series for indoor inline
applications).
Discharge outlet configurations:
Can be round or rectangular and out the back or bottom.
Available Voltages:
All Dexon blower heaters require two circuits; one for controls and one for
heating elements. Controls require 120VAC and heating elements can be 120,208,240,480 or
600 Volt and can be 1 phase or 3 phase.
External Alarm Interfacing:
An optional “95ALM” three alarm status output relay module is
available for interfacing with external alarms or PLC. The alarm module can be easily added
after installation if required.
Manual Mode Interfacing:
A set of manual mode interfacing terminals is available for dry
contact only, input from PLC, Hatch/Lid Switch, Gas Detector etc. dry contacts to temporarily
initiate “Manual” mode (full fan speed) for added safety.
