VTS Electric Heaters User Manual

: June 9, 2024
: VTS

Table of Contents

VTS Electric Heaters
Possible installation standards
Scope of application
Technical details
Electrical connection and protection
Wiring diagrams
Maintenance procedure
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VTS Electric Heaters

VTS-Electric-Heaters-fig-1

Possible installation standards

For VVS and VVSc AHUs, the electric heater made of plasters can be used in two different ways (VVSs heaters are only available in a non-insulated duct variant):

Electric heater in an non-insulated duct

Non-insulated duct – all plasters installed in a short duct with a junction box on the side.
When insulating the ventilation ducts, which include an electric heater in this version, make sure that the connection point (especially
its ventilation openings) is outside the insulating layer.

Electric heater in the AHU casing
Full installation in original housing – the heater and its power connection box will be installed inside the “empty section” of the relevant
air handling unit. For such an installation, the slices will not be mounted in the duct (blocks mounted directly to the inner surface of
the empty AHU section).

Scope of application

The maximum power of electric heaters available for given sizes and types of AHUs is shown below. A full list of the available powers will be provided in Chapter 3 – Technical Details.

Modular AHU – VVS

Size – VVS	21	30	40	55	75	100	120	150	180	230	300	400	500	650
Maximum slices number	pcs	2	3	3	3	3	3	3	3	3	3	3	3	3
Single slice power	kW	18	18	24	30	30	36	36	36	36	36	36	36	36
Total heater power	kW	36	54	72	90	90	108	108	108	108	108	108	108
108	108

Compact Standing AHU – VVSc

Size – VVSc	21	30	40	55	75	100	120	150
Maximum slices number	pcs	2	3	3	3	3	3	3
Single slice power	kW	18	18	24	30	30	36	36
Total heater power	kW	36	54	72	90	90	108	108

Compact Suspended AHU – VVS

Size – VVSs	5	10	15	20	30
Maximum slices number	pcs	1	1	2	2
Single slice power	kW	10	12	18	18
Total heater power	kW	10	12	36	36

NVS AHU

Size – NVS	23	39	65	80
Maximum slices number	pcs	1	2	3
Single slice power	kW	18	18	18
Total heater power	kW	18	36	54

Technical details

The current version of electric heaters is delivered in two power variants – low power, adjusted to AHUs with relatively low heating demand, and high power, for AHU cases for facilities with higher thermal requirements. These types differ mainly in the types of electrical connections of the individual heaters in the assembly (star connection for low power or delta connection for high power).
Appropriate connection between the heaters is made at the heater production stage – the installer only needs to connect the power and control cables – it is not allowed to modify the heater system connections in relation to the factory configuration.

Control
The graphs below show how the voltage supplying the modulated slice changes depending on the required heat demand:

VTS-Electric-Heaters-fig-4

Each time the modulated slice reaches full power, the demand is transferred to the next slice, which starts working at full capacity. Any
additional heating power will be realized by smoothly increasing the adjustable heating power of the modulated slice.

Available heaters power variants for the AHUs – low power

AHU type and size

| ****

power [kW]

| ****

power box type

| power cable 1
---|---|---|---
current L1/L2/L3 [A]| circuit breaker [A]| conductor cross-section [mm2]
VVS005s| 2,5| 1×18| 6,3/6,3/0| 10| 1,5
VVS010s| 3| 1×18| 7,5/7,5/0| 10| 1,5
VVS015s| 6| 1×18| 8,7/8,7/8,7| 16| 2,5
VVS020s| 6| 1×18| 8,7/8,7/8,7| 16| 2,5
VVS030s| 6| 1×18| 8,7/8,7/8,7| 16| 2,5
VVS021c / VVS021| 6| 1×18| 8,7/8,7/8,7| 16| 2,5
VVS030c / VVS030| 6| 1×18| 8,7/8,7/8,7| 16| 2,5
VVS040c / VVS040| 6| 1×18| 13/7,5/7,5| 16| 2,5
VVS055c / VVS055| 9| 1×18| 16,2/16,2/8,7| 20| 2,5
VVS075c / VVS075| 9| 1×18| 16,2/16,2/8,7| 20| 2,5
VVS100c / VVS100| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS120c / VVS120| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS150c / VVS150| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS180| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS230| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS300| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS400| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS500| 12| 1×18| 17,3/17,3/17,3| 20| 2,5
VVS650| 12| 1×18| 17,3/17,3/17,3| 20| 2,5

Available heaters power variants for the AHUs- high power

__

AHU type and size

| | __

power [kW]

| __

power box type

| power cable 1| power cable 2
---|---|---|---|---|---
current L1/L2/L3 [A]| circuit breaker [A]| conductor cross- section [mm2]| current L1/L2/L3 [A]| circuit breaker [A]| conductor cross- section [mm2]
VVS005s| 10| 1×18| 21,6/12,5/12,5| 25| 4| –| –| –
VVS010s| 12| 1×18| 26/15/15| 32| 6| –| –| –
VVS015s| 18| 1×18| 26/26/26| 32| 6| –| –| –
VVS015s| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS020s| 18| 1×18| 26/26/26| 32| 6| –| –| –
VVS020s| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS030s| 18| 1×18| 26/26/26| 32| 6| –| –| –
VVS030s| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS021c / VVS021| 18| 1×18| 26/26/26| 32| 6| –| –| –
VVS021c / VVS021| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS030c / VVS030| 18| 1×18| 26/26/26| 32| 6| –| –| –
VVS030c / VVS030| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS030c / VVS030| 54| 4×18| 52/52/52| 63| 16| 26/26/26| 32| 6
VVS040c / VVS040| 24| 2×18| 41/41/26| 50| 10| –| –| –
VVS040c / VVS040| 48| 4×18| 41/41/26| 50| 10| 41/26/41| 50| 10
VVS040c / VVS040| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS055c / VVS055| 30| 2×18| 52/41/41| 63| 16| –| –| –
VVS055c / VVS055| 60| 4×18| 52/52/52| 63| 16| 41/41/26| 50| 10
VVS055c / VVS055| 90| 6×18| 78/78/78| 100| 25| 52/52/52| 63| 16
VVS075c / VVS075| 30| 2×18| 52/41/41| 63| 16| –| –| –
VVS075c / VVS075| 60| 4×18| 52/52/52| 63| 16| 41/41/26| 50| 10
VVS075c / VVS075| 90| 6×18| 78/78/78| 100| 25| 52/52/52| 63| 16
VVS100c / VVS100| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS100c / VVS100| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS100c / VVS100| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS120c / VVS120| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS120c / VVS120| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS120c / VVS120| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS150c / VVS150| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS150c / VVS150| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS150c / VVS150| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS180| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS180| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS180| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS230| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS230| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS230| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS300| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS300| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS300| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS400| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS400| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS400| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS500| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS500| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS500| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
VVS650| 36| 2×18| 52/52/52| 63| 16| –| –| –
VVS650| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16
VVS650| 108| 6×18| 78/78/78| 100| 25| 78/78/78| 100| 25
NVS23| 18| 1×18| 26/26/26| 32| 6| –| –| –
NVS39| 36| 2×18| 52/52/52| 63| 16| –| –| –
NVS65| 54| 4×18| 52/52/52| 63| 16| 26/26/26| 32| 6
NVS80| 72| 4×18| 52/52/52| 63| 16| 52/52/52| 63| 16

Electrical system details

grid type	TN
rated supply voltage [V]	3×400
rated insulation voltage [V]	400
rated impulse withstand voltage [V]	2500

rated short-time current Icw for individual circuits – effective value of the periodic component withstood for 1s, i.e. the short- circuit current expected at switching voltage [A]| 6000
rated short-circuit current [A]| 6000
coincidence factor| 0,8
rated frequency [Hz]| 50
ingress protection level| IP00
permissible operating temperature [°C]| 0-50
control circuits supply voltage DC [V]| 24

Electrical connection and protection

The power connection should be made via a separate switchgear, which is not supplied with the VTS delivery. The wiring for powering the electric heater must be led through the panel on the back of the unit. If the cabling is led through the inspection panel from the front side, it should be arranged in such a way as to enable the opening of the section for maintenance and service works.
The connection of the heater should be made in such a way that the heater cannot be turned on when the fans are not working – this is done by factory-installed, serial connected safety devices in the form of a thermostat and a pressure switch, preventing the heater from being turned on if the temperature and air flow conditions are not met.
In case of fan stoppage, it is absolutely necessary to turn off the heater power supply.
The type of cables used for each function of the heaters is presented in the table below (the cable cross-section and its protection should be selected on the basis of the information provided in the tables in Chapter 3 – Technical details).

cable (s) for powering the electric heaters

| rated voltage| 3x400V AC
---|---|---
type| multi-core cable, copper conductor – twisted cable
work temperature [°C]| -30 – 60

control system power cable

| rated voltage| 230V AC
type| multi-core cable, copper conductor – twisted cable
work temperature [°C]| -30 – 60

control system control cable

| rated voltage| 24V DC
type| multi-core cable, copper conductor – twisted cable
work temperature [°C]| -30 – 60

Heater wiring can be divided into two parts:

Group of cables with connection independent of the type of heater
Group of cables, the connection of which changes with the type of heater and the components used in the AHU

Terminal number

|

Terminal name

|

Signal name

|

Connect to:

|

Type of control box

|

Connection terminal on the control box

---|---|---|---|---|---

1

|

GND

|

Ground

|

->

| CBX| G0
Compact| G0
Other| GND

3

|

24VDC

|

Power 24VDC

|

->

| CBX| G
Compact| G
Other| +24V DC

X

| Sections quantity
X| 1| 2| 3

4

|

St1

|

Stage 1

|

->

| CBX| G| G| G
Compact| G| G| G
Other| +24V DC| +24V DC| +24V DC
L| L|

Power 230V AC

|

->

|

230V AC

N| N

A1

|

A1

|

Work confirmation

|

->

| CBX| DI2
Compact| DI2
Other| free voltage contact

A2

|

A2

Signal name

| __

Connect to:

| Type of control box| __

Type of heater

| __

Terminal name on the control box

---|---|---|---|---|---|---
__

__

2

| __

__

0-10V

| __

__

Signal 0-10V DC

| __

__

->

| __

__

CBX

__

Compact

X

| Sections quantity
1| 2| 3
__

__

5

| __

__

St2

| __

__

Stage 2

| __

__

->

| __

__

CBX

| main| –| K1.24| K1.24
preheater| –| NO3| –
reheater – AHU with DXH| –| K1.24*| –
reheater – AHU with hum.| –| NO3| –
reheater – other| –| NO3| –
__

__

Compact

| main| –| K1.24| K1.24
preheater| –| DO6| –
reheater – AHU with DXH| –| K1.24*| –
reheater – AHU with hum.| –| DO6| –
reheater – other| –| DO6| –
Other| all| –| +24V DC| +24V DC
__

__

6

| __

__

St3

| __

__

Stage 3

| __

__

->

| __

__

CBX

| main| –| –| NO6
preheater| –| –| –
reheater – AHU with DXH| –| –| –
reheater – AHU with hum.| –| –| –
reheater – other| –| –| –
__

__

Compact

| main| –| –| DO5
preheater| –| –| –
reheater – AHU with DXH| –| –| –
reheater – AHU with hum.| –| –| –
reheater – other| –| –| –
Other| all| –| –| +24V DC

Views of examplary power boxes

VTS-Electric-Heaters-fig-5
VTS-Electric-Heaters-fig-6

marking	component	connection	remarks
1	relays	manufacturer	–
2	heaters connectors	manufacturer	–
3	heater	manufacturer	–
4	pressure switch	manufacturer	the pressure switch pipes are connected by

breakers

8| control connectors –

controls

| user| –

The presented views of power boxes are intended to illustrate the arrangement of components inside their housing. Please note that
they are only illustrative – when making electrical connections, always follow the wiring diagrams provided in Chapter 5 – Wiring
Diagrams.

Thermostat

The functionality of the thermostat is based on the properties of the bimetallic element – it opens the contacts of the heater control
circuit at an air temperature near the thermostat of 65 ° C. After an emergency switch-off, the heater switches on automatically when
the air temperature drops by 20 ° C. After intentional or emergency (caused by overheating) power off, the supply fan must run for a
certain time (0.5–5 min) so that the heaters reach the normal temperature.
The thermostat is an integrated, factory-installed component of each heater slice – it does not require additional assembly or electrical
connection by the installer.

function| protection of the heater against overheating (temperature control of the heating elements)
---|---
__

structure

| -metal housing

-two screw terminals

-bimetallic element with NC contact function

rated work voltage [V DC]| 30
type of output signal| free voltage (switching contact)
activation temperature [°C]| 65±3
temperature hysteresis [°C]| 17±3

Pressure switch

The pressure switch is another, next to the thermostat, element protecting against the heater’s operation in forbidden conditions. It
prevents the heater from being switched on when the pressure generated by the AHU’s fan sets is insufficient to ensure safe operation
of the heating elements.
Similarly to the thermostat, the pressure switch is a factory-installed and electrically connected component – connection of the
pressure hoses of the pressure switch should be made in accordance with the following recommendations:
- one of the tubes should be brought out to atmospheric pressure – in the case of installation of the power box on the duct
  (outside), the pipe does not need to be connected – there is atmospheric pressure present in the power box
- the second tube should be connected to the overpressure or underpressure in the AHU or in the duct (before or after the air
  supply fan)
- in the duct version of the heater, it is allowed to move the pressure switch outside the power box to avoid the need to run
  long measuring pipes – recommended position of the pressure switch – horizontal, with a vertical position the reading is 11Pa
  higher compared to the actual one
The pressure switch switching threshold is 20 Pa. After connecting to the AHU, check if the pressure switch is working properly for the lowest AHU airflow available. In the absence of the detected pressure difference, the place of connection of the second pressure hose to the installation should be changed.
In the opposite case – when for a given pressure switch setting, the pressure difference is detected even when the AHU is turned off
(heater operation is allowed despite the lack of fans operation), the setpoint should be gradually increased until the correct operation
is obtained – its sign is that the electric heater does not work despite the signals from the control device appearing if the pressure
switch does not detect the pressure difference between the measurement channels – the permission should take place only after the fans are started.
After the pressure switch is fully connected, perform the heater shutdown test. To do so, it is necessary to force the electric heater to
be manually controlled (e.g. by providing heater control signals from the controller) and at the same time to stop the fans. The pressure switch should prevent the operation of the electric heater (it will be visible e.g. by disconnecting the contactors in the switchgear).

function| protecting the heater against overheating (fan compression control)
---|---
__

structure

| -plastic housing

– two screw terminals

-a membrane connected to a mechanical module

rated work voltage [V DC]| 30
type of output signal| free voltage (switching contact)
measuring range [Pa]| 20-300

Wiring diagrams

In this chapter, wiring diagrams for each heaters power will be presented, sorted depending on the type and size of the AHU. Pay attention to the following markings:

VTS-Electric-Heaters-fig-31

For some high power configurations it is required to use two 3x400V power cables, according to a given diagram – this is dictated by the smaller cross-sections of the conductors and the reduction of the required bending radii thanks to this procedure.
For heaters with the capacity of 90kW and 108kW, factory-equipped with two sets of three B32 switches, connect the power cables to the terminals of the central switches of each set!
Green percentages on the diagrams inform about the division of the heater power into the various stages of the heater activation.
For example:
This notation means that the smoothly regulated part of a given heater constitutes 25% of its power (0-10V DC). The second step – switched on/off (ST2) is also 25%, while the third step – switched on/off (ST3) is 50% of the total power of the heater.
These parameters should be reflected in the appropriate uPC3 driver settings. The settings are made on the HMI Advanced screens:
- A05 for pre-heater
- A09 for main heater
- A06 for re-heater
If in a given system one or both stages switched on/off are not present (no ST2 / ST3 markings in the diagram), the value of 0% should be selected in the controller settings in the appropriate position.

**Low power – 2.5kW – VVS005s

VTS-Electric-Heaters-fig-10