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VENTS NKV 900x500-3

  • Description
  • Characteristics
  • Downloads
  • Dimensions
  • Additional diagrams
  • Legend

Duct water heaters are designed for heating of supply air in rectangular ventilating system and are applicable in supply or supply and exhaust units.


The heater casing is made of galvanized steel, the manifold is made of copper tubes and the heat exchange surface is made of aluminium plates. The heaters are available in 2, 3 or 4 rows modifications and designed for operation at maximum operating pressure 1,6 MPa (16 bar) and maximum operating temperature +100°С. The exhaust manifold of the heater has a branch pipe for submersible temperature sensor or iicng protecting device. The heater has a nipple to provide the system deaeration.


The heater design ensures its mounting by means of a flange connection. The water heater can be installed in any position to enable its deaeration. The air stream shall match the pointer on the heater.

The heater shall be installed in such a way as to enable the uniform air distribution along the entire cross section.

The air filter shall be installed at the heater inlet to provide protection against dust and dirt.

The heater can be installed both at the fan inlet or outlet. If the heater is located at the fan outlet the air duct length between the heater and the fan shall be at least 1-1.5 m to ensure the air flow stabilization as well as permissible air temperature level inside the fan.

The heater shall be connected on the counterflow principle, otherwise its efficiency can drop by 5-15%. All the nomographic charts in the catalogue are valid for such connection.

If waters serves as a heat transfer agent the heaters are designed for indoor installation only. For outdoor installation use antifreeze mixture (i.e. ethylene glycol solution).

To ensure the correct and safe heater operation use the automation system that provides the complex control and freezing protection:

  • automatic control of heating elements capacity and air heating temperature;
  • switching ventilating system on with preliminary heating by the heater;
  • use of air curtains equipped with spring-loaded actuator;
  • filter checking by means of differential pressure sensor;
  • fan shutdown in case of water coils freezing danger.
Connection against air flow Connection along air flow

Air pressure loss in the water heaters NKV

NKV rectangular series

Parameter NKV 900x500-3
Measurement unit
Weight 41.2 kg
Number of water coil rows 3 -
Rectangular duct size Rectangular duct size 900х500 mm
Heating water heating -
Width 900 mm
Height 500 mm
Duct for rectangular air ducts -
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"NKV" user's manual 11-2021 (V37EN-04) (pdf 571.81Kb)
"NKV (rectangular)" product description 02-2016 (pdf 1.44Mb)
Download high quality image "NKV (rectangular)" (psd 1.93Mb)
Download image "NKV (rectangular)" for your website (png 694.04Kb)
VENTS NKV 900x500-3
Parameter Value Measurement unit
B 900 mm
B1 920 mm
B2 940 mm
B3 1065 mm
H 500 mm
H1 520 mm
H2 540 mm
H3 450 mm
L 200 mm
L1 42 mm
L2 58 mm
K G 1'' in
Additional diagrams
Additional diagrams

How to use water heater diagrams:

Air Speed. Starting from 7000 m3/h on the air flow scale draw a vertical line 1 till the air speed axis. It makes 4.4 m/s.

  • Supply air temperature. Prolong the line 1 up to the point where it crosses the outside air temperature (blue curve), e.g. -20°C; then draw a horizontal line 2 from this point to the left till  crossing  water in/out temperature curve (90/70 °C). From this point draw a vertical line 3 to the supply air temperature axis on top of the graphic (+28°С).
  • Heating coil capacity. Prolong the line 1 up to the point where it crosses the outside air temperature indicated as red curve (e.g., -20°С) and draw a horizontal line 4 from this point to the right to the intersection of water in/out temperature curve (e.g., 90/70 °С). From this point draw a vertical line 5 up to the scale of heating coil capacity (124.0 kW).
  • Water discharge. Prolong the line 5 down to water discharge axis at the bottom of the graphic 6 (1.55 l/s).
  • Water pressure drop. Draw the line 7 from the point where line 6 crosses the black curve to the pressure drop axis (28.0 kPa).

Series   Flange designation (WxH) [mm]   Number of water coil rows
  400x200; 500x250; 500x300; 600x300; 600x350; 700x400; 800x500; 900x500; 1000x500   2; 3; 4
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