Air curtain frequently asked questions.

Have a question about our recessed or surface mounted air curtains? Or simply want to learn more about our over door heater range?
Our air curtain FAQ guide can help. Choose from technical and installation support, controls support, product support and information about packing and transport from the drop-down list below to learn more about our HVAC products.


What is Thermal Cut-Out (TCO?)

In the event of a low, or no airflow the TCO will operate to switch off the electrical supply to the heating elements on electrical heated units. This prevents a dangerous situation where overheating electrical elements could start a fire.

Why does the Thermal Cut Out (TCO) keeping trippingon electric heated units?

The most common reasons for the TCO (or both TCO’s in the case of 2m units) tripping are incorrect installation, insufficient maintenance, or inappropriate heat and fan settings.

Incorrect installation

  • Make sure surface mounted units are not fitted in the ceiling void
  • Check the gap above the air curtain. For surface mounted units this should be at least 100mm.
  • Make sure the discharge air stream is not being deflected back into the cabinet by the top edge of the doorway or any other doorway obstruction

Insufficient maintenance

  • Check air ventilation holes and inlet/outlet grilles are not blocked
  • Make sure the fan impellers, housing, motors and filters (if fitted) are free of dust and debris
  • Ensure the whole unit is thoroughly cleaned at least every three months. See O&M instructions for details

Inappropriate heat and fan settings

  • Check the controller settings are correct for the situation and conditions e.g. within small lobbies.
  • Air curtain should always be switched on, and off, from the remote control to allow the run-on cycle to function
  • When air curtains are in operation, and the mains supply is isolated, the run-on cycle cannot function.
  • Excessive heat output in a confined space can create nuisance tripping of the TOC.

How do I find the TCO?

On surface mounted and recessed units, the TCO is labelled ‘Press to reset.’ On Designer units, it is marked with a red circle.

Surface mounted units
On C units the TCO is located on the top of the outer case.

Recessed units
On all recessed air curtains, the TCO is located inside the unit above the electric elements. The grille core will need to be removed in order to access the TCO.

Designer units
On Designer units, the TCO is around ten holes in from the left and three rows in from the back and is behind a bigger air hole.

How will I know that the TCO has tripped?

Air curtains manufactured from 2015 onwards:

The LEDs on the Ecopower remote control will flash on and off.

Air curtains manufactured before 2015:

The status LED on the Ecopower PCB inside the air curtain will be continuous red. (You will need to access the air curtain to check this).

What do I need to check before I reset the TCO?

Before resetting ensure there is adequate air flow from the air curtain, and that the unit has been commissioned as per the installation, operation and maintenance instructions.

How do I reset the TCO?

Air curtains manufactured from 2015 onwards:

Switch off the electrical supply to the air curtain and allow 10 minutes for it to erase the EEPROM. Then turn the power back on and press the Auto Reset button on the EcoPower remote control four times.

Air curtains manufactured before 2015:

Switch off the electrical supply to the air curtain. Access the TCO inside the unit and press the red button until it clicks in (There are two TCOs on 2m units or longer; you may need to reset both). Switch electrical supply back on.

How will I know the reset has been successful?

Air curtains manufactured from 2015 onwards:

The air curtain heaters will come back on and, after 30 seconds, the LEDs on the remote control will stop flashing.

Air curtains manufactured before 2015:

The air curtain heaters will come back on and the status LED on the Ecopower PCB inside the air curtain will change from continuous red to flashing green.

What should I do if the fuses keep blowing?

Check that no wires are trapped, and all connections are correct. Make sure all fuses have the right breaking capacity (maximum current that can be safely interrupted by the fuse). See the O&M instructions for more details?

Where are the internal fuses located?

The internal fuses are located on the EcoPower PCB and inside the air curtain:

  • Fuse 6.3A(T) supplies the fan motors within the air curtain
  • Fuse 100mA(F) controls the circuitry of the EcoPower PCB

What should I do if the heating elements are not getting hot?

  1. Check all wires are correctly connected to the control panel, elements and wall controller.
  2. For electric models ensure the correct supply is present and appropriately connected. Most electrical heated models require a 3-phase 208v, 600v 480v electrical supply, they will not heat with a 1-phase 230v supply.
  3. The Thermal Cut Out (TCO) may have tripped and overheated

What is the typical casing temperature under normal operating conditions?

Under normal operating conditions the casing temperature should be between 60-80°C. A thermal protection device is embedded in the winding of each motor to prevent overheating.

Why is the motor running hot?

The most likely cause of the motor running hot is a build-up of dust or dirt deposits on the fan impellers. This can cause vibration, noise and excessive wear on the motor bearings.

How do I reduce the risk of overheating?

Regular cleaning will minimise the risk of overheating, optimise the efficiency of your air curtain, and prolong its operating life. We recommend that units are cleaned at least once every three months.

Can electric units be factory downrated to single phase?

No, this is not possible.

Can LPHW units be downrated?

Unfortunately, we cannot down rate water heated units. However, you can manually reduce the output by selecting half heat on the controller. This will half open the three way valve. Please note that this may well not provide enough heat output for a normal air curtain installation.

Can I master and slave Electric and LPHW units?

Yes, all you need to do is purchase a 3m interconnecting cable. Change the position of DIP switch three on the master unit to ON and turn the DIP switch on the slave units to the OFF position. Refer to the installation, operation and maintenance instructions for more details.

How many units can I master and slave?

A single Ecopower controller can operate up to eight units.

Do I need to change any DIP switches on the PCB during installation?

All DIP switches are pre-set for normal operation (with the exception of Designer and vertical units). It is only necessary to change the DIP switch settings if the air curtain is to be operated on a master/slave basis.

What information do I need to supply for a water coil calculation?

To provide a coil calculation, we need the following details:

  • Air curtain type and size
  • Water temperature in
  • Water temperature out
  • Room temperature

The difference in heat may vary even with small differences in water and air temp. Standard room temperature in our calculations is 20 C.

Please note we calculate for the air curtain operating at high fan speed.

Why is there a burning smell when the unit is switched on after it has not been used for a while?

When an air curtain is turned off for an extended period of time, dust and debris can settle on the electric heating elements. Before switching any unit back on it should always be inspected and cleaned to ensure safe and efficient operation.

If you are in any doubt, please contact the Thermoscreens service department.

What should I do if the fan is running, but the unit is not generating any heat?

Heating problems are usually associated with the connection to the controller or by insufficient water flow.

  • Verify the status of the LED on the Eco Power PCB board
  • If the LED is flashing green: operation is normal
  • If the LED is flashing red: this means low supply voltage, remote control not plugged in or RJ cable fault
  • If the LED is permanently on red: this means overheat safety cut-out(s) open circuit from an overheat situation
  • Check the diverter valve is wired correctly to the PCB board. See wiring diagram in the instructions.
  • Make sure there is no air in the heating coil or system, and bleed the unit if necessary
  • Check the hot flow and cold return to ensure there is a sufficient water flow rate

If the water flow is low, the system may need balancing, or the pump may be faulty or too small.

What should I do if only one side of the unit is working?

Check the connections to ensure there is no loose wiring. Make sure the fan is correctly aligned and not binding on anything. Check the elements, contractor and PCB board for faults. Then recheck both two motors, if one of them has seized it will need to be replaced.

How do I fit the three port water control valve?

It is very important to connect ports A and B correctly. A to the water coil and B as the bypass. See figure below showing heating pipe work.


Image can be found here

Can I use the unit without the three-way valve?

If the unit is fitted without the three-way valve the fan settings will work correctly, but you will not able to change the heat settings on the unit in automatic or manual mode. The only way to control the heat output without the three-way valve is using the valves built into the water system.


Where will I find the status LED?

The status LED is fitted on the PCB board inside the air curtain and shown as LED1 on the wiring diagrams.

What does a pulsing green light mean?

A pulsing green light means the unit is operating correctly.

What does a pulsing red light mean?

A pulsing red light indicates a low supply voltage, or that the ECO Power controller is not connected to the unit. Check the wiring between the PCB and controller.

What does a flashing alternate green/red light mean?

If the LED alternates between green and red the DIP switches are incorrectly set (refer to Operators Manual for details).

What does a permanent red light mean?

A permanent red light on an electric unit means the Thermal Cut Out has tripped and needs to be reset.

On the LPHW unit a permanent Red light indicates that a connector is missing and there is an open circuit. Both pins on the J2 location on the motherboard must be connected to close the circuit.

Can I fit a door switch control to the EcoPower PCB?

Door limit switches can be fitted to either IN0 or IN1 depending on door strategy. All units sold in North America are supplied with N/O magnetic reed switch, input at IN0.

How far can I extend the EcoPower core data cable?

The controllers standard 6m cable can be extended up to 50m. The extended cable must be routed away from electrical and data cables to avoid noise and impaired functionality.


Can I fit a time clock to an existing unit to switch it on/off?

Time clocks can be fitted to existing units. We recommend the Horstmann Centaur Plus C17 Series 2 or equivalent, 7-day single channel time switch with volt free contacts. Part number:

How do I identify an air curtain on site?

All of our products are fitted with a data plate, which shows the serial number and model type.

Surface mounted units: The data plate is located behind the left hand end cap.
Recessed units: The data plate is located inside the unit on the left hand side of the casing.

NB: left or right hand refers to when the unit is installed, viewing from inside the occupied space.

What parts are supplied as standard?

All free hanging units are supplied complete with controller, 6m of cable, end panels, door switch and wall brackets; and

All recessed are supplied complete with controller, 6m of cable, door switch.


Where will I find the EcoPower controller and other accessories ?

The EcoPower controller is bubble wrapped within the electrical side of the return grille other items boxed with the end panels.