Troubleshooting Information

The owner’s manuals below contain general information for installation & maintenance as well as troubleshooting guides. For more detailed information specific to your unit, please contact Dexon. Internal & field wiring diagrams can be found on the inside of the units access panel.

Owner’s Manuals 

Blower Heaters

MDH
MDH-HC
MDHIL
MDHIL-HC
SMDH
WMDH
IMDH
OWMDH

Owner’s Manuals 

Regulated Velocity Blower Heaters

SRVDH
WRVDH
IRVDH
OWRVDH

Owner’s Manuals

Vent Fans

SMDV
WVOD
MDV
MDVIL
MDVS
MDVILS
SMVOD
IMVOD
WMVOD

FAQ's - click to expand

Frequently Asked Questions

This website is intended to provide general information and does not provide all the requires specifics to properly select/size a blower heater or vent fan model. There are many variables to consider when selecting/sizing a blower heater or vent fan model and we do suggest you contact us directly to ensure you get the right product for your application.

General Questions

  1. Can I use a blower heater for freeze protection for a wet well?

No, while often used for this purpose Dexon blower heaters are not designed/intended to heat a space since depending on the location it can be very inefficient and recirculation space heaters simply make more sense in terms of energy consumption. The intent is rather to provide positive pressure safety ventilation and temper the outdoor air ahead of the discharge/outlet before it enters a confined space so as not to be the cause of the space freezing.

Given that, there are many other reasons why the space may freeze, just a few are: excessive heat loss from within the space, piping from the discharge/outlet exposed to the ambient environment, blower heaters not run continuously or not repaired when required etc.

The maximum discharge/outlet air temperature setting for a Ordinary location rated blower heater is +21 degree C, and for a Class 1, Division 2 rate units it is +15 degree C, the minimum discharge / outlet temperature in both cases is +5 degree C.

  1. Can Dexon make Class 1, Division 1 rated vent fans & blower heaters?

Dexon blower heaters and ventilation fans are and have always been rated for either Class 1, Division 2, Gas group C & D, Temp code T2C (T4 for Vent fans) or Ordinary Locations since that is the requirement for the Water, Wastewater industry that we market.

  1. Do you have any other distributors?

 Dexon Canada Air Systems Inc. sells products across all of Canada and we operate out of a single branch in Calgary, Alberta. All of our products are built to meet specific project requirements; therefore we do not have any distributors.

  1. When I buy a blower heater, what comes with it?

Typically a blower heater is sold with a status board & 8 meters of status cable. We are able to provide additional cable & accessories such as output alarm modules upon request. We also provide a copy of the Owner’s manual, located in an envelope on the inside cover of the blower heater.

  1. Does Dexon do commissioning and/or installs?

If feasible/practical we are able to provide commissioning services for an additional charge, but the Blower heater installation instructions in the submittal information and owner’s manual outline the startup information and the units are fully tested/set up and ready to go so the simple answer is we can provide a commissioning service if necessary but it doesn’t happen often.

Regarding Installation of our equipment, this is not something we get involved with. .

  1. What is the certification of the blower heater or vent fan?

Dexon blower heaters & vent fans are certified by the Canadian Standards Association.

  1. What is the typical delivery timeframe?

The delivery time for a smaller blower heater or vent fan is usually between 4-6 weeks upon receipt of the purchase order. For a larger vent fan or blower heater it is generally between 6-8 weeks. Delivery times may still vary depending on production load at the time of order.

  1. Will Dexon have a representative come & service my unit?

We are able to make service call to some units depending on the travel distance etc.

  1. Where can I get a copy of the owner’s manual for my unit?

All blower heaters & vent fans are sent out with a copy of the owner’s manual affixed the front, inside cover of the unit. We also provide generic copies of owner’s manuals in the Technical Support section of our website. Job specific portions of the owner’s manuals will require a phone call or email to us at 403-272-0562 or sales@dexoncanada.com.

  1. Where can I find troubleshooting information?

Troubleshooting information can be found in the owner’s manual supplied with the blower heater or vent fan. Additionally you can locate this information under the troubleshooting section of our website.

  1. What are the maintenance requirements of my unit?

Maintenance requirements are detailed in section 5 of the owner’s manual supplied with the blower heater or vent fan. Additionally you can locate this information under the troubleshooting section of our website.

  1. I heard there was an upgrade available to the air proving, how can I get this?

In 2018, Dexon phased out the use of air velocity sensors as a means of air proving.

All new blower heaters will automatically be equipped with fan/blower Tachometer feedback as the means for detecting if the fan/blower has stopped for any reason and a retrofit/upgrade kit is available for any existing units that are currently equipped with an EE575 or EE671 airflow transmitter. Contact Dexon for more info regarding this or to order the kit. Note that we would need to know the details of any particular unit such as the serial number and location of the installation etc.

 

Technical Questions

  1. Can I use Teck Cable instead of the status cable provided?

Yes Teck cable can be used instead of the supplied status cable, we recommend not uses anything larger than 16 gauge and be sure to get the required number of conductors/pairs as the requirements change based on the particular model, for example units with 1, 2 or 3 stages of heating or a RVDH series unit etc.

  1. What type of discharge/outlet air temp. sensor is used in the blower heater?

We use a “TD5A” RTD (resistive temperature device) located near the discharge/outlet of the blower heater which provides a signal to the main controller (95DH or RVDH) and ultimately to the status indicator and alarms via the main controller.

  1. What is a “95ALM” Three Alarm Module & what does it do?

The “95ALM” Three Alarm Status Output Relay Module is an optional module that plugs into the back of the status indicator and used for providing a means to interface with external alarms via dry contacts to alert when an event/condition has occurred beyond the normal operation of the blower heater. For wiring options or further information please your products owner’s manual or check out the how to section of our website.

  1. What is the difference between the SMDH & SVRDH Series?

The SRVDH series blower heater provides particulate filtration to the intake/inlet air of a blower heater and automatically regulates the fan/blower speed to maintain a preset airflow as the flow becomes restricted do to filter losses or any other obstruction. It will do so until the fan/blower has reached full speed and a “Max Speed” signal is sent to the status indicator followed by a “No air” signal and alarm if the “RDALM” alarm module is used in conjunction.

  1. Can your units be used for negative pressure/exhaust fans?

Dexon units are designed & intended to provide continuous positive pressure ventilation, tempered as required to a confined space or building for safety ventilation as required by the nation and local codes that govern this action. They rely on the continuous outdoor air to protect themselves from some of the gases and moisture often associated with spaces like sewage wet wells for example, drawing in air from these sorts of spaces not only create a unsafe environment for personnel entering the space but also prematurely corrode anything in the airstream such as heating elements, fan, overheat sensors etc. Dexon can supply exhaust fans, but only to draw air from spaces where the air is non-corrosive.

  1. I need help troubleshooting, what kind of information do I need to provide you?

When contacting us for technical support please ensure you are able to provide us the job name/location as well as the model & serial number for the unit you are inquiring about.

  1. Can I run that power & status cable together in the same conduit?

Do NOT install status board cable in the conduit intended for heating element and power circuits. Doing so will put the extra low voltage circuits in close proximity to low voltage circuits which may cause signal interference.

  1. The lift station is freezing, what can I do to fix this?

Dexon blower heaters are not designed/intended as the primary means of preventing a lift station from freezing, rather to provide safety ventilation while tempering the intake/inlet air as required not to be the cause of the space to freeze, if the unit is shutdown or requires repair this must be remedied ASAP in some cases the piping leading to the space would need to be blocked to prevent cold outdoor air from entering until the problem can rectified. We recommend other measures of protection from freezing such as heat trace/tape on valves etc.

  1. What kind of tools will I need for maintaining & repairing my Dexon unit?

The following tools will are required to perform basic regular maintenance procedures & minor repairs;  Particulate air filters if servicing a RVDH model with intake filters, A cordless drill with a Philips bit for removing access panels, a small flathead screw driver for any adjustment that might be require to potentiometers on the main controller if called to do so by Dexon, a medium flathead screw driver for tightening power supply terminals, a brush for brushing debris off the louvers/intake, fan, heating elements, sensors and other electrical components.

A Voltmeter, Amp meter and a Dexon temperature simulator or iced beverage can be used to create a demand for heat when not cold enough outdoors.

  1. What do the lights on the status board / power supply mean?

A detailed explanation of the status indications can be found in the supplied owner’s manual as well as in the troubleshooting section of our website.

  1. The “Element” LED is blinking on the Status Board, what does that mean?
    The “Element 1” LED may be off, steady on or blinking. An off LED would indicate there is no heat demand; a steady on LED would indicate there is a heat demand requiring full element capacity; a blinking LED would indicate the heat demand is being met by intermittent pulses of energy. Element 2 & 3 – indicate stage 2 or 3 are required to maintain the desired temperature. These LEDs will not blink they will remain constant.

 

 

Installation Questions

  1. How do I mechanically install / mount this unit?

Installation instructions vary depending on which model of vent fan of blower heater you have. Instructions are located in section 4 of the supplied owner’s manual and can also be found under the technical support section of our website.

  1. Does my Dexon unit have to be mounted on the ground or can I lift it up?

For outdoor units we recommend that you maintain a 305mm (12”) clearance to the bottom of the air intake louvers or hood for accumulating debris or drifting snow, if raised on a flanged pipe, the pipe needs to be able to support the weight or the unit through the various climatic conditions that may be encountered at the install location. Any sort of pipes that is exposed to the climate may also need to be insulates so as not to create heat loss between the discharge/outlet of the unit and space to be ventilated.

 

 

Model Selection / Sizing Questions

  1. How do I size/select the proper model for my application?

There are many factors that contribute to the selection of the correct unit for you application. We advise that you contact a Dexon representative for help with this to ensure the correct model is selected to suit your specific needs. A series of questions will be asked such as the Location of the project, the on-site voltage available, the airflow requirement or space size and air changes required and the Classification rating required, discharge temperature to be maintained etc.. These questions can also be addressed in the “Contact Us” page of our website.

  1. What size pressure relief vent/gooseneck do I require?

We recommend a pressure relief/goose neck at least equal in cross section to the unit discharge/ outlet.

  1. How much space do I need to leave around my Dexon unit?

We recommend a minimum of 1 meter (3’3”) clearance on the control access side the unit as well as the louvers/intake side for servicing & maintenance which can involve removing the controls section and/or louver section.

 

General Information - click to expand

This website is intended to provide general information and does not provide all the requires specifics to properly select/size a blower heater or vent fan model. There are many variables to consider when selecting/sizing a blower heater or vent fan model and we do suggest you contact us directly to ensure you get the right product for your application.

Blower Heaters and Vent Fans- General Information

  •  Dexon blower heaters and vent fans are intended to provide continuous positive pressure ventilation to pumping station wet wells, dry wells, buildings, vaults and chambers etc based on local code requirements or as specified.
  • All blower heaters or vent fans require pressure relief vents in order to promote the specific air changes within the spaces requiring ventilation.
  • All Dexon blower heaters are electric and available in any standard Canadian supply voltage.
  • Blower heaters temper the supply air in order to mitigate the risk of freezing the ventilated space. Alternate means of freeze protection may be required if freezing of the confined space is a concern.
  • Blower heaters do have a ventilation failure feature and output for external alarms.
  • Vent fans do not temper the supply air.
  • Vent fans do not have a ventilation failure feature
  • Must run continuously once installed on an active wet well or other moist corrosive environment.
  • Dexon housings/bodies come in various configurations and sizes depending on the model, heating and airflow capacity etc.
  • Housings/ bodies are somewhat flexible in terms of whether inlets and outlets are rectangular or round, protruding collars or flat etc. and if the aluminum wall mounting brackets, aluminum outdoor inlet hoods and surface mounted louver sections etc are required.
    • Dexon blower heaters can be equipped with a optional “95ALM” Output relay Alarm Module to interface with PLC or Auto-Dialler etc.
    • Dexon blower heaters can be equipped with terminals on the status indicator to accept a dry Contact from an external source such as a man-lid switch or PLC etc that puts the unit into “manual” mode for intermittent high speed operation intended for temporarily flush/ventilate the space prior to/during entry by personnel.
    • Dexon blower heaters are not intended to provide heating of confined spaces for the purpose of freeze protection but rather to provide safety ventilation and temper the supply air where required in order to not be the cause of freezing the space.
  • Dexon blower heaters do not monitor the temperature within a confined space; they are designed to maintain a preset discharge/ outlet air temperature which is intended to temper the discharged air as required or specified.
  • Dexon blower heaters are not 2 speed but rather adjustable in “auto” mode and full speed in “manual” mode depending on switch position on status indicator.
  • Dexon vent fans are 2 speed with a switch and do have limited adjustment of both low/idle speed and high/full speed.
  • Dexon vent fans should never be used where freezing is a concern since they are intended to be operated continuously regardless of the outdoor conditions.
  • Components used inside Dexon blower heaters and vent fans are not all corrosive resistant and are therefore they are intended to operate continuously to prevent migration of gases/moisture from the ventilated space into the fan/heating element section of the unit thereby causing premature corrosion.

 

  1. Sizing / Selecting considerations:
    • Blower heaters do have the “ventilation failure” feature while the ventilation fans do not.
    • Geographic location of the proposed installation is important in determining the requirements for sizing/selecting the appropriate model. Some locations require different air flow rates (6 or 12 continuous air changes per hour, 30 intermittent air changes per hour etc.), is it located in colder climates.
    • The physical location of the blower heater or vent fan will also provide information required for proper sizing/selecting. For example the classification of area, indoor or outdoor, wall mounted or ceiling hung, what the required discharge temperature setting might be, what the required outdoor design temperature might be etc.
    • Class 1, Div 2 blower heaters have thermostats on each of the heating elements that prevent gas ignition temperatures on the element skin from potentially occurring. In some cases/conditions, this can reduce the overall expected heating capacity by de-energizing/cycling the heating element(s) until cooled sufficiently by the outdoor air/fan. This process occurs so that the thermostat resets and once again allows the heating; this dynamic is also a consideration when sizing/selecting an appropriate model.
  • Dexon equipment/products are all constructed from aluminum for its anti-corrosive properties and therefore Dexon does not fabricate flanges, pipe adapters or any other peripherals fabricated from any other metal unless absolutely necessary and agreed upon well in advance of production/fabrication.
  • All blower heaters require 2 power circuits, a 120VAC circuit for fan/controls and a heating circuit of whatever desired/required standard Canadian supply voltage.
  • Heating circuit requirements vary with regard to wattage and voltage etc, the available on site voltage needs be known in advance for sizing/selection.
  • In the case of blower heaters, the discharge air temperature setting requirements and outdoor design temperatures need to be known for sizing/selecting the correct model.

 

  1. Installation considerations:
  • All screws must be used in any outdoor unit to maintain Type 3R rating.
  • Do not cover any of the controls with insulation.
  • All screws should be checked/secured before energizing as they may have loosened during shipping
  • Status indicators are not weather resistant and therefore need to be mounted in a safe dry environment or in a weather tight enclosure if outdoors.
  • Status indicators are required to be mounted remote from hazardous location.
  • Pressure relief vents should be equal to the discharge outlet of the blower heater or vent fan and located a sufficient distance from the Dexon unit to prevent the unit from drawing in the exhausted air.

 

  1. Maintenance:

 

  • Blower heaters are no longer sold with airflow sensors or airflow switches in the airstream, rather the fan rotation is monitored and indications/alarms for “Fan Stopped” occur when the fan has stopped for any reason. There are retro fit kits available for this “TachOp upgrade” and it is highly recommended as it prevents erroneous alarms from sensors/switches that fail or collected substantial debris etc. This upgrade eliminates these devices which also reduces maintenance.
  • As with all ventilation equipment, louvers/inlets and pressure relief vents need to be maintained and clear of any debris or hoar frost etc.
  • All blower heaters and vent fans are designed to be able to remove the complete fan/controls section in one piece in order to service/maintain the unit with the exception of the WVOD series vent fan and the MDH or MDHIL series blower heaters where the fan is located in the louvered section or cap/top section.
  • If upon inspection it is apparent that parts need replacing that may be difficult to be done on site such as heating elements; in many cases the entire control section can be sent to Dexon for evaluation and repair/refurbish if it is a good candidate.
  • Maintenance care as described in the Dexon owner’s manuals must be done at the very least once a year, more often in more active or high debris areas.
  • It is important to ensure that blower heaters and vent fans are operating continuously where wet wells are concerned due to condensation build-up on louvers and premature corrosion of parts that cannot be made as resistant.
  • If the blower heater happens to have an airflow sensing device (older models) keeping it free of debris and moisture is very important and locations near trees or construction sites will require more frequent cleaning & maintenance.
  • Airflow sensors in blower heaters (if equipped) are extremely sensitive to debris and corrosive air in the airstream and extremely fragile when handling for cleaning of the protective screen.

Product Warranty - click to expand

Limited Warranty

 Dexon Canada Air Systems Inc. warrants its Blower Heater and Vent Fans to be free of defects in material and workmanship for a period of one (1) year from start up or eighteen (18) months from shipment, whichever comes first.

This warranty does not extend to abnormal or abusive wear and tear or improper installations and operations.  All units and components of the unit must be installed according to Dexon’s installation instructions provided with each unit.  Responsibility for proper installation and operations must rest on the purchaser. Once properly installed all units must be operated as intended and maintained as outlined in owners and operators manuals supplied with each unit, and as per tags on each unit.

If the unit is shut down for any reason the unit must be completely sealed off to prevent any fumes from entering the inside of the unit. This includes ducting/discharge, conduit and bolt holes, or any holes that would allow air to migrate into the unit. When removing the inside panels for repair or service, the discharge duct and any holes must still be covered in such a way as to prevent moisture from entering the body of the Blower Heater or Vent Fan.

Dexon’s sole obligation under this warranty shall be to replace or repair defective parts or workmanship if upon evaluation it has been determined that they are defective and not a result of abnormal or abusive wear and tear or improper installations and operations.

Warranty services will only be extended to the original purchaser. In order to obtain warranty service the owner must ship the product prepaid to Dexon for evaluation.  Dexon will ship the replaced or repaired product back prepaid if evaluation has determined that they are defective.

 

Dexon Canada Air Systems Inc.

5018 80th Ave. SE

Calgary, AB  T2C 2X3

Phone: (403) 272-0562, Fax: (403) 235-0149

Email: dexoncan@dexoncanada.com, techsupport@dexoncanada.com

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