Hoval RoofVent LHW-9, RoofVent LKW-9, RoofVent LHW-10, RoofVent LKW-6, RoofVent LKW-10 Design Handbook

RoofVent

®

Design Handbook

Supply and Extract Air Handling Units
for Heating and Cooling High Spaces

Safety

3

A

RoofVent® LHW

Supply and extract air handling unit with energy recovery
for heating high spaces

7

B

RoofVent® LKW

Supply and extract air handling unit with energy recovery
for heating and cooling high spaces

35

C

RoofVent® twin heat

Supply and extract air handling unit with high-capacity energy recovery
for heating high spaces

63

D

RoofVent® twin cool

Supply and extract air handling unit with high-capacity energy recovery
for heating and cooling high spaces

89

E

RoofVent® twin pump

Supply and extract air handling unit with reversible heat pump
for heating and cooling high spaces

117

F

RoofVent® condens

Supply and extract air handling unit with gas condensing boiler
for heating high spaces

149

G

RoofVent® direct cool

Supply and extract air handling unit with single-split cooling system
for heating and cooling high spaces

175

H

RoofVent® LH

Supply and extract air handling unit with optimum fresh air rate
for heating high spaces

207

I

RoofVent® LK

Supply and extract air handling unit with optimum fresh air rate
for heating and cooling high spaces

235

J

Options

265

K

Control systems

287

L

System design

299

M

Operation

305

N

2

Safety A

1 Symbols _____________________________________ 5

2 Operational Safety ____________________________ 5

3 Information for a User Manual ___________________ 5

Safety

Content

4

5

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1 Symbols

Caution

This symbol warns against risks of injury. Please heed
all instructions designated by this symbol to prevent
injuries and/or death.

Attention

This symbol warns against risks of property damage.
Please heed the respective instructions to prevent
risk of damage to the unit and its functions.

Note

This symbol denotes information about the economic
use of the equipment or special tips.

2 Operational Safety

RoofVent® units are state of the art design and are safe
to operate. Nevertheless, hazards may emanate from the
units if they are used incorrectly or not used as intended.
Therefore:

■ Please read the operating instructions before unpacking,

installing, commissioning and before maintaining the
equipment.

■ Store the operating instructions so that they are easily

accessible.

■ Observe all appropriate informational and warning signs.

■ Follow the local safety and accident prevention regula-

tions at all times.

■ RoofVent

®

units may only be installed, operated and main-

tained by authorized, skilled and trained specialists.

Specialists as dened by these operating instructions are

those persons who, based on their training, knowledge
and experience as well as their knowledge of the rele­vant regulations and guidelines, can carry out the work
assigned to them and recognize potential hazards.

3 Information for a User Manual

According to the accident prevention regulations of some
countries, the operator of equipment must meet certain
requirements for the prevention of occupational accidents
and instruct the operating personnel as to the hazards that
may occur and how to prevent them. This can be done with
the help of the user manual.
In addition to national regulations for accident prevention and
environmental protection, a user manual should also include
the most important items of the operating instructions.

Safety

Symbols

6

RoofVent® LHW

Supply and extract air handling unit with energy recovery
for heating high spaces

B

1 Use ________________________________________ 8

2 Construction and operation______________________ 8

3 Technical data _______________________________ 15

4 Design example ______________________________ 24

5 Options ____________________________________ 26

6 Control systems______________________________ 27

7 Transport and installation ______________________ 28

8 Specication texts ____________________________ 32

RoofVent® LHW

Content

8

1 Use

1.1 Intended use

RoofVent® LHW units are used to supply fresh air, for
the disposal of extract air as well as for heating coupled
with energy recovery in high spaces. Also included under
intended use are compliance with the installation, commis­sioning, operating and maintenance provisions (operating
manual).
Any use beyond this is considered improper use. The
manufacturer shall not be held responsible for any damage
resulting from such use.

1.2 User group

RoofVent® LHW units may only be installed, operated and
serviced by authorised and trained specialist personnel who
are familiar with the equipment and aware of the dangers
involved.
The operating manual is for English-speaking operating
engineers and technicians as well as specialists in building,
heating and ventilation technology.

1.3 Risks

RoofVent® LHW units are built to correspond to the state of
the art and to current safety standards. However, despite all
precautionary measures taken, there are still some potential
hazards which are not immediately obvious, such as:

■ Dangers when working with the electrical systems

■ During work on the ventilation unit, parts (e.g. tools) may

fall or be dropped.

■ Dangers when working on the roof

■ Damage to devices or components due to lightning

■ Malfunctions as a result of defective parts

■ Hazards from hot water when working on the hot water

supply

■ The ingress of water through the roof unit if the access

panels are not closed correctly

2 Construction and operation

The RoofVent® LHW provides fresh air supply and extract air
removal as well as heating for large spaces (production halls,

shopping centres, sports halls, exhibition halls etc.). It fulls

the following functions:

■ Heating (with connection to central hot water supply)

■ Fresh air supply

■ Extract air removal

■ Recirculation

■ Energy recovery

■ Air distribution via Air-Injector

■ Air ltration

A ventilation system consists of several autonomous
RoofVent

®

LHW units and, as a rule, works without supply
and extract air ducts. The units are decentrally installed in
the roof and are also serviced from roof level.

Thanks to their high output and efcient air distribution,

RoofVent

®

LHW units have a large operating range. This
means that compared with other systems, only few units are
necessary to create the required conditions.
Three unit sizes, various coil types and a series of acces­sories make it possible to provide a customised solution for
any hall.

2.1 Unit construction

The RoofVent® LHW consists of the following components:

■ Roof unit with energy recovery: self-supporting casing

made of Aluzinc sheet steel, insulated inside (class B1)

■ Filter box: available in three standard lengths per unit size

for adjusting to specic dimensional requirements

■ Heating section:

coil connections possible on each side (usually under­neath the extract air grille)

■ Air-Injector:

patented, automatically adjustable vortex air distributor for
draught-free air distribution over a large area

The unit is delivered in two sections: roof unit and below-roof
unit (see Fig. B1). The components are bolted together and
can be dismantled individually.

RoofVent® LHW

Use

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2.2 Air distribution with the Air-Injector

The patented air distributor – called the Air-Injector – is the
core element. The air discharge angle is set by means of the

adjustable guide vanes. It depends on the air ow rate, the

mounting height and the temperature difference between
the supply air and room air. The air is therefore blown into
the room vertically downward, conically or horizontally. This
ensures that:

■ each RoofVent

®

LHW ventilates and heats a large oor

area,

■ no draughts occur in the occupied area,

■ the temperature stratication in the room is reduced, thus

saving energy.

Above-roof unit:
Roof unit with energy recovery

Below-roof unit:

a Filter box
b Heating section
c Air-Injector

Fig. B1: Components of the RoofVent® LHW

a

b
c

RoofVent® LHW

Construction and operation

10

RoofVent® LHW

Use

11

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Actuator Air-Injector:
adjusts the supply air discharge direction continuously from vertical to
horizontal

Frost controller:
prevents the coil freezing

Extract air grille

Extract air lter:

bag lter with differential pressure switch for lter monitoring

ER damper and bypass damper:
opposed dampers for regulation of energy recovery, with actuator

Access panel:

access to extract air lter

Weather louvre door:

access to the fresh air lter and to the DigiUnit terminal box

Fresh air lter:

bag lter with differential pressure switch for lter monitoring

Fresh air damper and recirculation damper:
opposed dampers for switching between fresh air and recirculation opera­tion, with actuator

Gravity damper:
closes the bypass during shutdown and thus prevents heat loss

Exhaust air fan:
twin impeller centrifugal fan with maintenance-free drive

Exhaust air grille:
access to exhaust air fan

Plate heat exchanger:
with bypass for energy recovery control and condensate drain

Access panel:
access to supply air fan

Supply air fan:
twin impeller centrifugal fan with maintenance-free drive

Access panel:
access to heating coil

Heating coil:

LPHW coil consisting of copper tubes with aluminium ns

Fig. B2: Components of the RoofVent® LHW

RoofVent® LHW

Construction and operation

12

Fresh air inlet through weather louvre door

Filter with differential pressure switch

Fresh air damper with actuator

Plate heat exchanger

Supply air fan

Silencer and diffuser

LPHW heating coil

Frost controller

Supply air sensor

Air-Injector with actuator

Extract air inlet through extract air grille

Extract air sensor

Filter with differential pressure switch

Recirculation damper (opposed to the fresh air damper)

ER/bypass damper with actuator

Gravity damper

Exhaust air fan

Silencer and diffuser

Exhaust air outlet through exhaust air grille

Fig. B3: Operational diagram, RoofVent® LHW

RoofVent® LHW

Construction and operation

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2.3 Operating modes

The RoofVent® LHW has the following operating modes:

■ Off

■ Ventilation

■ Ventilation (reduced)

■ Recirculation

■ Recirculation night

■ Exhaust air

■ Supply air

■ Night cooling summer

■ Emergency operation

The DigiNet control system controls these operating modes automatically per
control zone, in accordance with the scheduler (exception: emergency operation).
In addition, you can:

■ manually switch the operating mode of a control zone,

■ switch each individual RoofVent

®

unit to the following operating modes: Off,

Recirculation, Exhaust air, Supply air and Emergency operation.

Code

1)

Operating mode Use Diagram Description

OFF Off

The fans are turned off. Frost protec­tion remains active. There is no room
temperature control.

If the unit is not
needed

Supply air fan ...................Off

Exhaust air fan ................. Off

Energy recovery ...............0 %

Fresh air damper .............. Closed

Recirculation damper .......Open

Heating ............................ Off

VE2 Ventilation

The RoofVent

®

unit blows fresh air
into the room and draws off spent
room air. Heating and energy recovery
are controlled depending on the heat
demand and temperature conditions.
The room temperature set value day is
active.

During room use

Supply air fan ................... On

Exhaust air fan ................. On

Energy recovery ............... 0 – 100 %

Fresh air damper .............. Open

Recirculation damper .......Closed

Heating ............................ 0 – 100 %

VE1 Ventilation (reduced)

Like VE2, but with reduced air ow rate

The room temperature set value day is
active.

During room use
(only for fans with

variable air ow

rate)

REC Recirculation

On/Off operation: In the event of heat
demand, the RoofVent

®

unit draws in
room air, warms it and blows it back into
the room.
The room temperature set value day is
active.

For pre-heating

Supply air fan ................... On

*)

Exhaust air fan ................. Off

Energy recovery ............... 0 %

Fresh air damper .............. Closed

Recirculation damper .......Open

Heating ............................ On

*)

*) during heat demand

RECN Recirculation night

Like REC, but with room temperature set
value night

During the night
and on weekends

RoofVent® LHW

Construction and operation

14

Code

1)

Operating mode Use Diagram Description

EA Exhaust air

The RoofVent

®

unit extracts spent
room air. There is no room temperature
control.

For special cases

Supply air fan ................... Off

Exhaust air fan ................. On

Energy recovery ............... 0 %

Fresh air damper .............. Open

Recirculation damper .......Closed

Heating ............................ Off

SA Supply air

The RoofVent

®

unit blows fresh air
into the room. Heating is controlled
depending on the heat demand and
temperature conditions.
Spent room air passes through open
windows and doors or another system
provides extraction.
The room temperature set value day is
active.

For special cases

Supply air fan ................... On

Exhaust air fan ................. Off

Energy recovery ............... 0 %

Fresh air damper .............. Open

Recirculation damper .......Closed

Heating ............................ 0 – 100 %

NCS Night cooling summer

On/Off operation: If current tempera­tures allow, the RoofVent

®

unit blows
cool fresh air into the room and extracts
warmer room air. The room temperature
set value night is active.
The unit blows the supply air vertically
downwards to achieve the greatest

possible efciency.

For free cooling
during the night

Supply air fan ................... On

*)

Exhaust air fan ................. On

*)

Energy recovery ............... 0 %

Fresh air damper .............. Open

*)

Recirculation damper .......Closed

*)

Heating ............................ Off

*) depending on temperature conditions

– Emergency operation

The RoofVent

®

unit draws in room air,
warms it and blows it back into the room.
The heater is switched on via manual
control of the mixing valve.
There is no room temperature control.

If the DigiNet
system is not oper­ating (e.g. before
commissioning)

Supply air fan ................... On

Exhaust air fan ................. Off

Energy recovery ............... 0 %

Fresh air damper .............. Closed

Recirculation damper .......Open

Heating ............................ On

1)

This is the code for the respective operating mode in the DigiNet control system (see Part L 'Control systems').

Table B1: Operating modes of the RoofVent

®

LHW

RoofVent® LHW

Construction and operation

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3 Technical data

3.1 Unit type reference

Below-roof unit

LHW - 6 / DN5 / LW + F00 - H.B - D / ...

Unit type

RoofVent

®

LHW

Unit size

6, 9 or 10

Control

DN5 Design for DigiNet 5
KK Design for non-Hoval control

Roof unit

Roof unit with energy recovery

Filter box

F00 Filter box, short
F25 Filter box, medium
F50 Filter box, long

Heating section and coil type

H.A Heating section with coil type A
H.B Heating section with coil type B
H.C Heating section with coil type C

Air-Injector

Options

Table B2: Unit type reference

3.2 Application limits

Extract air temperature max. 50 °C

Extract air relative humidity max. 60 %

Moisture content of extract air max. 12.5 g/kg

Fresh air temperature Min. -30 °C

Heating medium temperature max. 120 °C

Operating pressure max. 800 kPa

Supply air temperature max. 60 °C

Minimum operating time VE2 min. 30 min

Table B3: Application limits of the RoofVent® LHW

RoofVent® LHW

Technical data

16

3.3 Air flow rate, electrical connections

Unit type LHW-6 LHW-9 LHW-10

Air distribution Nominal air ow rate

1)

Supply air m³/h 5500 8000 8800

Exhaust air m³/h 5500 8000 8800

Floor area reached Max. m² 480 797 915

Energy recovery Heat recovery efciency, dry % 60 63 57

Heat recovery efciency, wet % 68 73 65

Fan characteristics Supply voltage V AC 3 x 400 3 x 400 3 x 400

Permitted voltage tolerance % ± 10 ± 10 ± 10

Frequency Hz 50 50 50

Active power per motor kW 1.8 3.0 4.5

Current consumption A 4.0 6.5 9.9

Set point of thermal relays A 4.6 7.5 11.4

Speed of rotation (nominal) rpm 1440 1435 1450

Actuators Supply voltage V AC 24 24 24

Frequency Hz 50 50 50

Control voltage V DC 2…10 2…10 2…10

Torque Nm 10 10 10

Run time for 90° rotation s 150 150 150

Filter monitoring Factory setting of differential pressure switch Pa 300 300 300

1)

Refers to: RoofVent® LHW with heating coil type B and vertical supply air discharge direction

Table B4: Technical data, RoofVent

®

LHW

RoofVent® LHW

Technical data

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3.4 Sound levels

Unit type LHW-6 LHW-9 LHW-10

Operating mode VE2

REC

VE2

REC

VE2

REC

Position

Sound pressure level (at a distance of 5 m) 1)dB (A) 46 60 58 47 46 52 66 57 49 48 54 68 60 52 51

Total sound power level dB (A) 68 82 80 69 68 74 88 79 71 70 76 90 82 74 73

Octave sound power level 63 Hz dB (A) 51 63 62 48 54 52 69 59 54 56 54 71 62 57 59

125 Hz dB (A) 55 71 70 56 63 63 78 70 60 63 65 80 73 63 66

2)

250 Hz dB (A) 61 76 74 64 63 65 81 71 63 66 67 83 74 66 69

500 Hz dB (A) 61 75 71 61 58 66 81 70 62 61 68 83 73 65 64

1000 Hz dB (A) 65 77 72 63 57 71 81 72 67 60 73 83 75 70 63

2000 Hz dB (A) 57 72 72 60 56 66 80 73 64 58 68 82 76 67 61

4000 Hz dB (A) 49 71 71 57 48 58 76 71 58 50 60 78 74 61 53

8000 Hz dB (A) 36 65 63 49 42 44 70 62 51 41 46 72 65 54 44

1)

with hemispherical radiation in a low-reection environment

2)

outdoors (roof unit)

Table B5: Sound levels, RoofVent

®

LHW

RoofVent® LHW

Technical data

18

3.5 Heat output

Note

The performance data listed here applies to the most frequent design conditions. Use the
selection program 'HK-Select' to calculate the performance data for other design data. You can
download 'HK-Select' free of charge on the Internet.

Fresh air temperature -5 °C -15 °C

LPHW Size Type Q Q

TGHmax

tS∆p

W

m

W

QQTGH

max

tS∆p

W

m

W

°C kW kW m °C kPa l/h kW kW m °C kPa l/h

80/60 LHW-6 A 37 20 16.2 28 8 1569 39 16 18.3 26 8 1663

LHW-6 B 52 36 12.4 36 14 2228 55 33 13.0 34 16 2363

LHW-6 C 80 64 9.5 51 13 3447 85 63 9.6 50 15 3656

60/40 LHW-6 A 23 7 25.0 21 3 984 25 3 25.0 19 4 1079

LHW-6 B 32 16 18.1 26 6 1393 36 13 20.4 24 8 1530

LHW-6 C 51 35 12.6 36 6 2185 56 33 12.9 35 7 2395

80/60

LHW-9

A 59 39 14.7 32 7 2544 62 34 15.7 30 7 2678

LHW-9

B 75 55 12.5 37 10 3235 79 51 12.9 36 11 3407

LHW-9

C 116 96 9.7 52 10 4984 122 94 9.8 51 11 5248

60/40

LHW-9

A 37 16 22.5 24 3 1570 40 12 25.0 22 3 1706

LHW-9

B 46 26 17.8 27 5 1992 51 22 19.4 26 5 2167

LHW-9

C 73 52 12.8 36 5 3119 79 51 13.0 36 5 3385

80/60 LHW-10 A 74 46 23.5 24 10 3173 74 35 23.5 24 10 3173

LHW-10 B 83 55 14.3 35 12 3549 88 49 15.2 33 14 3778

LHW-10 C 129 101 10.8 50 12 5529 137 98 10.9 49 14 5887

60/40 LHW-10 A 50 22 25.0 16 5 2151 50 11 25.0 16 5 2151

LHW-10 B 52 24 21.5 25 6 2231 57 18 25.0 23 7 2465

LHW-10 C 82 54 14.4 35 6 3528 91 52 14.8 34 7 3888

Legend: Type = Type of heating coil

Q = Heat output
Q

TG

= Output to cover fabric heat losses

H

max

= Maximum mounting height

t

S

= Supply air temperature

∆p

W

= Water pressure drop

m

W

= Water ow rate

Refers to: Room air 18 °C, extract air 20 °C/40 % rel. humidity

Table B6: Heat output, RoofVent

®

LHW

Note

The output for coverage of the fabric heat losses (Q

TG

) allows for the ventilation heat requirement

(Q

V

) and the energy recovery output (QER) under the respective air conditions. It is calculated as

follows:

QTG = Q + QER – Q

V

RoofVent® LHW

Technical data

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3.6 Minimum and maximum distances

X/2

X

Y

Unit type LHW-6 LHW-9

LHW-10

Align the RoofVent® units so that no unit draws in the
exhaust air from another unit as fresh air.

The extract air grille must be easily accessible.

Provide a clear space of approx. 1.5 m on the side
opposite to the heating coil connections for service and
maintenance.

The stream of supply air must be able to spread unob­structed (note position of beams and lamps).

Unit clearance X Min. m 11.0 13.0 14.0

Max. m 22.0 28.0 30.0

Mounting height Y

1)

Min. 1)m 4.0 5.0 5.0

Max.

2)

m 9.0 … 25.0

1)

The minimum height can be reduced by 1 m in each case using the 'Air

outlet box' option (see Section K 'Options').

2)

The maximum height varies depending on the ancillary conditions (for

values, see Table B6).

Table B7: Minimum and maximum distances

RoofVent® LHW

Technical data

20

3.7 Dimensions and weight

Roof unit LW

Filter box short F00 / medium F25 / long F50

Heating section H

Air-Injector D

Cable feedthroughs for electrical connections

Access panel

Return

Flow

Fig. B4: Dimensional drawing for RoofVent® LHW (dimensions in mm)

RoofVent® LHW

Technical data

21

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Unit type LHW-6 LHW-9 LHW-10

Dimensions of
roof unit

A mm 2100 2400 2400

B mm 1080 1380 1380

C mm 1390 1500 1500

D mm 600 675 675

E mm 1092 1392 1392

Dimensions of
below-roof unit

Filter box design F00 F25 F50 F00 F25 F50 F00 F25 F50

G mm 940 1190 1440 980 1230 1480 980 1230 1480

S mm 1700 1950 2200 1850 2100 2350 1850 2100 2350

H mm 530 780 1030 530 780 1030 530 780 1030

F mm 980 1240 1240

J mm 410 450 450

K mm 848 1048 1048

M mm 270 300 300

N mm 101 111 111

O mm 767 937 937

P mm 758 882 882

Q mm 490 570 570

R mm 900 1100 1100

V mm 500 630 630

Heating coil
data

Coil type ABCABC ABC

Water content l 3.1 3.1 6.2 4.7 4.7 9.4 4.7 4.7 9.4

L " Pipe thr. 1 ¼

(female)

Pipe thr. 1 ½

(female)

Pipe thr. 1 ½

(female)

Weight Roof unit kg 390 560 565

Below-roof unit (with F00) kg 130 130 137 182 182 192 182 182 192

Filter box F00 kg 63 82 82

Heating section kg 30 30 37 44 44 54 44 44 54

Air-Injector kg 37 56 56

Total (with F00) kg 520 520 527 742 742 752 747 747 757

Filter box F25

1)

kg + 11 + 13 + 13

Filter box F50

1)

kg + 22 + 26 + 26

1)

Additional weight compared to the design with lter box F00

Table B8: Dimensions and weights, RoofVent

®

LHW

RoofVent® LHW

Technical data

22

3.8 Air flow rate with additional pressure drops

Pressure increase in Pa Exhaust air

LHW-6

0

0 2

0 4

0 6

0 8

0 0 1

0 2 1

0 4 1

0 6 1

0 8 1

0 0 2

0 2 2

0 4 2

0 0 0 6 0 0 5 5 0 0 0 5 0 0 5 4 0 0 0 4

Supply air

Example:
An additional
pressure drop of
84 Pa results in a

new air ow rate of

5100 m³/h.

Air ow rate in m³/h

Diagram B1: Air ow rate, RoofVent® LHW-6 with additional pressure drops

Pressure increase in Pa Exhaust air

LHW-9

0

0 2

0 4

0 6

0 8

0 0 1

0 2 1

0 4 1

0 6 1

0 8 1

0 0 2

0 2 2

0 4 2

0

0 5 8 0 0 0 8 0 0 5 7 0 0 0 7 0 0 5 6

Supply air

Air ow rate in m³/h

Diagram B2: Air ow rate, RoofVent® LHW-9 with additional pressure drops

RoofVent® LHW

Technical data

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Pressure increase in Pa Exhaust air

LHW-10

0

0 2

0 4

0 6

0 8

0 0 1

0 2 1

0 4 1

0 6 1

0 8 1

0 0 2

0 2 2

0 4 2

0

0 0 9 0 0 5 8 0 0 8 8 0 0 0 8 0 0 5 7 0 0 0 7

Supply air

Air ow rate in m³/h

Diagram B3: Air ow rate, RoofVent® LHW-10 with additional pressure drops

RoofVent® LHW

Technical data

24

4 Design example

Design data

■ Required fresh air ow rate or air change rate

■ Hall geometry (length, width, height)

■ Design fresh air temperature

■ Desired room temperature (in the occupied area)

■ Extract air conditions

1)

■ Fabric heat losses (portion to be covered by the

RoofVent

®

units)

■ Internal heat gains (machines, lighting, etc.)

■ Heating medium

1)

The extract air temperature is generally higher than the temperature in the

occupied area. This is the result of unavoidable temperature stratica-

tion in high spaces, but is reduced to a minimum with the Air-Injector.

A temperature gradient of only 0.2 K per metre height can therefore be

assumed.

Example

Fresh air ow rate ......................................30'000 m³/h

Hall geometry (L x W x H) ......................52 x 45 x 9 m

Design fresh air temp. ......................................... -5 °C

Desired room temperature...................................18 °C

Extract air conditions ............................... 20 °C / 40 %

Fabric heat losses ........................................... 220 kW

Internal heat gains ............................................. 36 kW

Heating medium ................................. LPHW 80/60 °C

Room temperature:..............................................18 °C

Temperature gradient: .................................... 9 · 0.2 K

Extract air temperature: ....................................≈ 20 °C

Required number of units n

req

Based on the air ow rate per unit (see Table B4), select a

trial unit size. (Depending on the results of further calcula­tions, repeat the layout design for another unit size if neces­sary.)

n

req

= V

req

/ V

U

V

req

= required fresh air ow rate in m³/h

V

U

= air ow rate for the selected unit size in m³/h

Approximate selection: Unit size LHW-9

n

req

= 30'000 / 8'000

n

req

= 3.75

Select 4 LHW-9s.

Actual fresh air ow rate V (in m³/h)

V = n · V

U

n = Selected number of units

V = 4 · 8'000
V = 32'000 m³/h

Effective fabric heat losses Q

Teff

(in kW)

Q

Tef f

= QT – Q

M

QT = fabric heat losses in kW
Q

M

= internal heat gains in kW

Use the following criteria for calculation of internal heat
gains (connected loads of machines and lighting): Operating
times, diversity, direct heat output through convection, indi­rect heat output through radiation, etc.

Q

Tef f

= 220 – 36

Q

Tef f

= 184 kW

Necessary output to cover fabric heat losses per unit
Q

TG

(in kW)

Q

TG

= Q

Tef f

/ n

Q

TG

= 184 / 4

Q

TG

= 46 kW

RoofVent® LHW

Design example

25

B

E

E

F

G

H

I

J

K

L

M

N

Selection of coil type

From Table B6, select the required coil type based on the
output necessary to cover the fabric heat losses per unit.

Select coil type B with 55 kW heat output to cover the fabric
heat losses at LPHW 80/60 °C and fresh air temperature

-5 °C.

Checking the ancillary conditions

■ Maximum mounting height

Select a different coil type or unit size if the actual

mounting height (= distance between the oor and

the bottom edge of the unit) is greater than maximum
mounting height H

max

(see Table B6).

■ Maximum oor area reached

Calculate the oor area reached per unit using the

selected number of units. If it exceeds the maximum
value listed in Table B4, increase the number of units.

■ Compliance with minimum and maximum distances

Check the resulting distances based on the hall geometry
and arrangement of the units, using the information in
Table B7.

Actual mounting height = 7.2 m
Max. mounting height H

max

= 12.5 m

→ OK

Floor area per unit = 52 · 45 / 4 = 585 m²

Max. oor area reached = 797 m²
→ OK

Minimum and maximum distances can be complied with
when units are arranged symmetrically.

→ OK

Denitive number of units

With a larger number of units, there is more exibility of

operation. However, the costs are also higher. For an
optimal solution, compare both the costs and ventilation
quality of the system.

Select 4 LHW-9s with heating coil type B. They ensure
cost-effective and energy-saving operation.

RoofVent® LHW

Design example

26

5 Options

RoofVent® LHW units can be adapted to the requirements of the specic project with a series of options.

You will nd a detailed description of all optional components in Section K 'Options' of this handbook.

Option Use

ColdClimate design For installation of the RoofVent

®

unit in areas where the fresh

air temperatures fall below –30 °C

Explosion-proof design For installation of the RoofVent

®

unit in explosive areas (Zone

1 and Zone 2)

Oil-proof design When using the RoofVent

®

unit in applications with high oil

content in the extract air

Hygiene design When using the RoofVent

®

unit in applications with higher

hygiene requirements (corresponds to VDI 6022)

Fans with variable air ow rate For operation of the unit with variable air ow rate

(supply air and exhaust air)

High-pressure fan, supply air To overcome additional external pressure drop

(e.g. from supply air ducts installed on-site)

High-pressure fan, exhaust air To overcome additional external pressure drop

(e.g. from extract air ducts installed on-site)

Hydraulic assembly diverting
system

To facilitate hydraulic installation

Magnetic mixing valve For continuous regulation of the heating coil (ready-to-

connect)

Fresh air silencer For reduction of noise from the weather louvre door

Exhaust air silencer For reduction of noise from the exhaust air grille

Supply air silencer For reduction of noise within the room

Extract air silencer For reduction of noise within the room

Acoustic cowl For reduction of noise within the room

(in the Air-Injector)

Actuators with spring return As additional frost protection (close the fresh air damper and

the ER damper during a power failure)

Air outlet box When using the RoofVent

®

unit in low-roofed halls

(instead of the Air-Injector)

Drop eliminator To drain condensate from the plate heat exchanger onto the

roof

Design for injection system For installation of the RoofVent

®

unit with a hydraulic injection

system (integrated pump control)

Table B9: Availability of options for RoofVent® LHW

RoofVent® LHW

Options

27

B

E

E

F

G

H

I

J

K

L

M

N

6 Control systems

There are basically two possibilities for controlling the RoofVent® LHW:

System Description

Hoval DigiNet We strongly advise that the RoofVent

®

LHW should be

controlled by Hoval DigiNet. This control system, developed

specically for Hoval indoor climate systems, offers the

following advantages:

■ DigiNet utilises the full potential of the decentralised

systems. It controls each ventilation unit individually,
depending on local conditions.

■ DigiNet allows for maximum exibility of operation with

respect to the control zones, unit combinations, operating
modes and operating times.

■ DigiNet regulates the air distribution and thus ensures

maximum ventilation efciency.

■ DigiNet regulates the energy recovery output in the plate

heat exchanger.

■ The ready-to-connect units with integrated control compo-

nents are easy to plan and install.

■ Commissioning of the DigiNet is quick and easy thanks

to the plug & play components and pre-addressed control
modules.

You can nd a detailed description of the Hoval DigiNet in Part

L 'Control systems' of this handbook.

Non-Hoval system RoofVent

®

LHWs can also be controlled with non-Hoval
systems. However, the non-Hoval system must take the special
features of the decentralised systems into account.
In the design for non-Hoval control, the RoofVent

®

LHW
comes only with a basic terminal box instead of the DigiUnit
terminal box. Additional information can be found in the sepa­rate description 'Terminal box unit RoofVent

®

LHW' (available

on request).

Table B10: Control systems, RoofVent® LHW

RoofVent® LHW

Control systems

28

7 Transport and installation

7.1 Assembly

Caution

Risk of injury as a result of incorrect handling. Have
transport and assembly work carried out by trained

specialists !

RoofVent

®

LHW units are delivered in 2 sections (roof unit,
below-roof unit) on a wooden pallet. Parts which belong
together are labelled with the same unit number.

Note

Depending on the optional components, the delivery
may consist of multiple parts (such as when a supply
air silencer is installed). In this case a forklift truck or
a crane is required for assembling the below-roof unit
on site.

The following guidelines are important when preparing for
assembly:

■ The units are assembled from roof level. A crane or heli-

copter is required.

■ To transport the unit to the roof, 2 hoisting slings are

required (approx. length 6 m). If steel cables or chains are
used, the unit corners must be properly protected.

■ Make sure that the roof frames correspond to the speci-

cations in Section M 'System design.'

■ Dene the desired orientation of the units (position of the

coil connections).

■ The units are held in the roof frame by means of their own

weight. Silicone, PU foam or similar is required for sealing.

■ For units with exhaust air silencers, additional attachment

to the roof frame is required.

■ Follow the assembly instructions included.

Fig. B5: RoofVent® roof
units are installed from
roof level.

7.2 Hydraulic installation

Caution

Risk of injury as a result of incorrect handling.
Hydraulic installation must be carried out by trained

specialists only !

The Hoval DigiNet control system is designed for a distributor
circuit with separate hydraulic connection of the units; i.e. a
mixing valve is installed in front of each unit. The diverting
system is used as standard.

Boiler system requirements

■ Adjust the hydraulic system to the control zone divisions.

■ Hydraulically coordinate the pipework for the individual

units within a control zone to ensure even distribution.

■ Starting at a fresh air temperature of 15 °C, the heating

medium (max. 120 °C) must be available at the mixing
valve without delay in the required amount and at the
required temperature.

■ A ow temperature control which is dependent on the

fresh air temperature is required.

The Hoval DigiNet control system switches the Enable
heating on for 1 minute once a week. This prevents the main
pump from blocking after a prolonged shutdown.

Pipework requirements

■ Use 3-way mixing valves with linear characteristics and

high quality.

■ The valve authority must be ≥ 0.5.

■ The valve actuator must have a short run time (5 s).

■ The valve actuator must be continuous, i.e. the stroke

changes in proportion to the control voltage (DC 0…10 V).

■ The valve actuator must be designed for emergency

operation with a separate manual control (AC 24 V).

■ Install the valve close to the unit (max. distance 2 m).

Caution

Risk of injury from falling parts. Do not apply any

loads to the coil, e.g. by means of the ow or return !

Note

Use the 'Hydraulic assembly' or 'Magnetic mixing
valve' options for quick and easy hydraulic installa­tion.

RoofVent® LHW

Transport and installation