VENTS NKP/NKD A21 V.2 Duct Heater User Manual

Safety Requirements

All requirements in this manual, along with applicable local and national construction, electrical, and technical norms, must be observed during installation and operation. Always disconnect the fan from the power supply before any connection, servicing, or repair operations. Installation is permitted only for qualified electricians with a work permit for electrical units up to 1000 V. Read this manual carefully before commencing work.

Before installation, check the unit for visible casing damage. Ensure the casing internals are free of foreign objects. Avoid compressing the casing during mounting. Misuse and unauthorized modifications are prohibited. Do not expose the unit to adverse atmospheric agents (rain, sun, etc.).

The transported air must be free of dust, solid impurities, sticky substances, or fibrous materials. Do not use the unit in hazardous or explosive environments (e.g., containing spirits, gasoline, insecticides). Do not block intake or extract vents to ensure efficient airflow. Do not sit on the unit or place objects on it. Do not touch the unit with wet or damp hands or when barefoot.

This unit is not intended for use by persons (including children) with reduced physical, sensory, or mental capabilities, or lack of experience and knowledge, unless supervised by a responsible person. Children should be supervised to prevent them from playing with the unit.

If the supply cord is damaged, it must be replaced by the manufacturer, its service agent, or similarly qualified persons to avoid a safety hazard.

CAUTION: To prevent inadvertent resetting of the thermal cut-out, this appliance must not be supplied through an external switching device (like a timer) or connected to a circuit regularly switched on/off by the utility.

Disposal: The product must be disposed of separately at the end of its service life. Do not dispose of the unit as unsorted domestic waste. ♻️

Purpose

The heater is designed for integration into a ventilation system and joint operation with an air handling unit equipped with a control system for switching on and controlling its operation.

Delivery Set

Designation Key

The model designation follows a specific structure:

• NKD: Duct reheater
• NKP: Duct preheater
• 125, 150, 160, 200, 250, 315: Air duct diameter [mm]
• 0.6, 0.8, 1.2, 1.7, 2.0, 3.0: Heater power [kW]
• 1: Phases (e.g., 1 for single-phase)
• A21 V.2: Compatibility with A21 automation without DB-9M connector

Technical Data

The heater is rated for indoor application with ambient temperatures ranging from -30 °C to +40 °C and relative humidity up to 80%. It is designed for connection to single-phase AC 230 V/50 (60) Hz power mains. The recommended minimum air flow speed in the air duct is 1.5 m/s. The heater is rated as a Class I electric appliance. Hazardous parts access and water ingress protection rating is IP40.

The heater design is subject to continuous improvement; therefore, some models may differ slightly from those described in this manual.

Model Specifications and Dimensions:

Design and Operating Principle

The diagram illustrates the components of the duct heater:

• 1: Control unit cover
• 2: Air flow direction indicator
• 3: Power cable
• 4: Thermal insulation (20 mm mineral wool)
• 5: Electric heating element
• 6: Connection cable to the unit
• 7: Thermal contact reset button

The reheater (NKD) maintains the supply air temperature at the level set by the unit controller. The preheater (NKP) maintains the air temperature in the intake duct to prevent the heat exchanger from freezing. The heater has two built-in thermal contacts for overheating protection: TK60 (actuates at +60 °C with automatic restart) and TK90 (actuates at +90 °C with manual restart). To restart the TK90 thermal contact, remove the control unit cover and press the button on the thermal contact.

Mounting and Set-up

READ THE USER'S MANUAL BEFORE INSTALLING THE UNIT.

Attach the NKD heater to the air duct connected to the supply air spigot. Attach the NKP heater to the air duct connected to the intake air spigot. The heater can be mounted horizontally or vertically.

Push the air ducts onto the flanges until they stop. Flexible ducts must be fixed rigidly with a metal worming clamp.

When mounted horizontally, the heater must be installed with the cover facing upwards. A maximum deviation of 90° is allowed. The heater must not be positioned with the cover facing downwards.

A duct temperature sensor must be installed for the NKD heater. Install the sensor in the supply duct downstream of the heater. Warning! The sensor must be mounted at a distance of at least 1 meter from the heater.

Ensure air duct tightness at the sensor mounting location.

Connection to Power Mains

POWER OFF THE POWER SUPPLY PRIOR TO ANY OPERATIONS WITH THE UNIT.

THE UNIT MUST BE CONNECTED TO POWER SUPPLY BY A QUALIFIED ELECTRICIAN.

The rated electrical parameters of the unit are given on the manufacturer's label.

ANY TAMPERING WITH THE INTERNAL CONNECTIONS IS PROHIBITED AND WILL VOID THE WARRANTY.

Connect the heater to the unit using the cable installed by the manufacturer, following the wiring diagram. The diagram shows connections for EVH/ENH designation, with the following names:

• EVH: Duct preheater
• ENH: Duct reheater
• ENH RT2*: Duct temperature sensor
• XP1: Power cord plug

The wiring diagram indicates wire colors: 1 - blue, 2 - black, 3 - grey, 4 - brown. The power connection is 230 VAC 50/60 Hz.

⚡ Electric shock hazard!

For the NKD heater, connect a duct temperature sensor to the unit. Connect the heater to AC single-phase 230 V/50 (60) Hz power mains using a pre-wired power cable with a plug.

Technical Maintenance

The heater should be inspected periodically for mechanical damage, checking seal tightness and secure duct fastening. Heater maintenance includes:

• Inspection of tightening of ground screw clamps and electric connections.
• Inspection of wire terminal connections.
• Cleaning of electric heating elements of dust and dirt. To clean the heating elements, disconnect the air ducts from the heater.

Troubleshooting

IF UNIDENTIFIED NOISES OR ODOURS SHOULD ARISE AND IN CASE OF DEFORMATION OF ELEMENTS OR VIBRATION, IMMEDIATELY DISCONNECT THE UNIT FROM POWER SUPPLY AND CONTACT THE SELLER FOR DIAGNOSTICS AND TO DETERMINE THE CAUSE OF THE FAULT. DIAGNOSTICS MUST BE CARRIED OUT BY QUALIFIED SPECIALISTS.

If troubleshooting steps have failed, contact the Seller of the product. In case of faults not described in the table, contact the Seller for further information.

Storage and Transportation Regulations

• Store the unit in the manufacturer's original packaging in a dry, closed, ventilated premise with temperatures from +5 °C to +40 °C and relative humidity up to 70%.
• The storage environment must not contain aggressive vapors or chemical mixtures that could cause corrosion, insulation, or sealing deformation.
• Use suitable hoist machinery for handling and storage operations to prevent damage.
• Follow handling requirements applicable to the cargo type.
• The unit can be transported by any mode of transport in its original packaging, provided it is protected against precipitation and mechanical damage. Transport only in the working position.
• Avoid sharp blows, scratches, or rough handling during loading and unloading.
• Before initial power-up after transportation at low temperatures, allow the unit to warm up to operating temperature for at least 3-4 hours.

Manufacturer's Warranty

The product complies with EU norms and standards on low voltage guidelines and electromagnetic compatibility (EMC Directive 2014/30/EU, Low Voltage Directive 2014/35/EU, CE-marking Council Directive 93/68/EEC). This certificate is issued following tests on product samples.

VENTS warrants normal operation of the unit for 24 months from the retail sale date, provided the user observes transportation, storage, installation, and operation regulations. Malfunctions occurring during the guaranteed period due to the manufacturer's fault entitle the user to free warranty repair at the factory. This includes work to eliminate faults and ensure intended use.

Warranty repair does not include: routine technical maintenance, unit installation/dismantling, or unit setup.

To benefit from warranty repair, the user must provide the unit, the user's manual with a purchase date stamp, and payment paperwork. The unit model must match the manual.

The manufacturer's warranty does not apply in the following cases:

• Failure to submit the unit with the entire delivery package or missing component parts.
• Mismatch of unit model/brand with information on packaging and manual.
• Failure to ensure timely technical maintenance.
• External damage to the casing or internal components caused by the user.
• Redesign or engineering changes to the unit.
• Use of unapproved assemblies, parts, or components.
• Unit misuse.
• Violation of installation or control regulations.
• Connection to power mains with a voltage different from the stated one.
• Unit breakdown due to voltage surges.
• Discretionary repair by the user.
• Repair by unauthorized persons.
• Expiration of the warranty period.
• Violation of transportation or storage regulations.
• Wrongful actions by third parties.
• Breakdown due to force majeure (fire, flood, earthquake, war, blockades).
• Missing seals (if provided by the manual).
• Failure to submit the manual with a purchase date stamp.
• Missing payment paperwork.

Following the stipulated regulations ensures long and trouble-free operation. Warranty claims require presentation of the unit, payment document, and user's manual with purchase date stamp.

Certificate of Acceptance, Seller Information, Installation Certificate, Warranty Card

These sections provide forms for recording unit acceptance, seller details, installation specifics, and warranty information. They include fields for Unit Type, Model, Serial Number, Manufacture Date, Seller details (name, address, contact), Purchase Date, Installation Technician details, Installation Date, and Warranty Period. These forms are intended to be filled out upon delivery, installation, and for warranty claims.