Hoval A 60 User manual

Rotary heat exchangers
for Heat Recovery in Ventilation Systems
Handbook for Design, Installation and Operation

Drive motor
The 3-phase gear motor with belt pulley
and v-belt is installed on a rocker in
the corner of the casing. The speed
of rotation is innitely adjustable.
Peripheral slide seal
Constant-force springs permanently press
the abrasion-resistant ring seal against the
casing. The patented system permanently
minimises leakage and allows the unit
to be sized for smaller air ow rates.
Adjustable purge sector
The size of the purge sector can be adjusted
to suit requirements. The device (patent
pending) prevents contamination of the
supply air by the extract air and at the same
time minimises purge and energy loss.
Storage mass
Hoval supplies the storage mass in three types of
material: for condensation, enthalpy and sorption
wheels. The sorption coating guarantees a consist-
ently high degree of humidity efciency, even under
summer conditions.

1
1 Principle and Operation __________ 2
1.1 Heat transmission
1.2 Humidity transmission
1.3 Leakage of rotary heat exchangers
1.4 Frost limit
1.5 Temperature efciency
1.6 Pressure drop
1.7 Pressure difference
1.8 Hygiene
1.9 Reliable data
2 Performance control ____________ 7
3 Structure _____________________ 8
3.1 Wheel
3.2 Casing
3.3 Peripheral slide seal
3.4 Transverse seal
3.5 Drive
4 Options _____________________ 11
4.1 Drive
4.2 Control unit
4.3 Operating unit
4.4 Rotational speed monitoring
4.5 Inspection cover
4.6 Purge sector
4.7 Duct design
4.8 Coated casing
4.9 Offset wheel position
5 Dimensions of the exchangers ___ 15
6 Unit type reference ____________ 16
7 System design ________________ 18
7.1 Hoval CASER design program
7.2 Design data
7.3 Local conditions, installation position
7.4 Wheel type
7.5 Performance control
7.6 Using and setting the purge sector
7.7 Mixing of the air streams
7.8 Supply air humidication
7.9 Corrosion
7.10 Application limits
7.11 Danger or contamination
7.12 Condensation in the warm air stream
8 Transport and installation _______ 21
8.1 Transport
8.2 Mechanical installation
8.3 Installation of sensors
8.4 Electrical installation
8.5 Assembly of segmented rotary heat exchangers
8.6 Storage
9 Commissioning and maintenance _ 22
9.1 Commissioning
9.2 Maintenance
10 Specication texts ____________ 23
10.1 Condensation wheel
10.2 Enthalpy wheel
10.3 Sorption wheel
Content

2
1 Principle and Operation
Hoval rotary heat exchangers are regenerators with rotating
heat accumulators (category 3) in accordance with the guide-
lines for heat recovery (e.g. VDI 2071).
The heat-dissipating and heat-absorbing air ows heat
or cool the rotating, air-permeable storage accumulator.
Depending on the air conditions and the surface of the
accumulator material, humidity may also be transferred in the
process. Supply and exhaust air must therefore be brought
together and ow through the heat exchanger.
The storage mass consists of triangular, axially arranged
small ducts made of thin metal foil. The depth of the storage
mass (viewed in the direction air ow) is generally 200 mm;
the airway height is normally 1.4 – 1.9 mm, depending on the
application. With these dimensions the storage mass gener-
ates a laminar ow in the wheel ducts.
Fresh air
t21
x21
Supply air
t22
x22
Exhaust air
t12
x12
Extract air
t11
x11
Fig. 1: Function diagram and air conditions
Denition of key data according to Eurovent
Temperature efciency t22 - t21
ηt = 
t11 - t21
Humidity efciency x22 - x21
ηx = 
x11 - x21
Legend: t = Temperature [K; °C]
x = Absolute humidity [g/kg]
Index: …11 Extract air
…21 Fresh air
…12 Exhaust air
…22 Supply air
1.1 Heat transmission
The wheel with its axially arranged, smooth ducts acts as a
storage mass, half of which is heated by the warm air and
the other half of which is cooled by the counter-ow of cold
air. The temperature of the storage mass therefore depends
on the axis coordinates (wheel depth) and the angle of
rotation.
The function is easy to understand by following the status
of a wheel duct through one revolution (see Fig. 3). The
following can be recognised with reference to the heat
transfer from this process:
■ The air temperature after the exchanger varies; it depends
on the location on the wheel.
■ The heat recovery efciency can be varied by varying the
speed.
■ The heat recovery efciency can be changed with the
storage mass. This can be done with different cross-sec-
tions of the wheel ducts, different thickness of the storage
material or by changing the wheel depth. However, in all
cases this varies the pressure drop.
■ The specic heat output depends on the temperature
difference between warm air and cold air. The rotary heat
exchanger is therefore suitable for heat and cool recovery,
i.e. for winter and summer operation.
Fig. 2: Geometry of
storage mass
Fig. 3: States depending on the turning angle
Principle and Operation

3
1.1 Heat transmission
The wheel with its axially arranged, smooth ducts acts as a
storage mass, half of which is heated by the warm air and
the other half of which is cooled by the counter-ow of cold
air. The temperature of the storage mass therefore depends
on the axis coordinates (wheel depth) and the angle of
rotation.
The function is easy to understand by following the status
of a wheel duct through one revolution (see Fig. 3). The
following can be recognised with reference to the heat
transfer from this process:
■ The air temperature after the exchanger varies; it depends
on the location on the wheel.
■ The heat recovery efciency can be varied by varying the
speed.
■ The heat recovery efciency can be changed with the
storage mass. This can be done with different cross-sec-
tions of the wheel ducts, different thickness of the storage
material or by changing the wheel depth. However, in all
cases this varies the pressure drop.
■ The specic heat output depends on the temperature
difference between warm air and cold air. The rotary heat
exchanger is therefore suitable for heat and cool recovery,
i.e. for winter and summer operation.
Fig. 2: Geometry of
storage mass
Fig. 3: States depending on the turning angle
Warm air entry
The rotation of the storage mass has
moved the wheel duct from the cold air
to the warm air. The storage material is
cooled almost to the temperature of the
cold air. This applies particularly to the
entry side of the cold air (= exit side of the
warm air). The warm air now ows through
the duct with reference to the temperature
in the counter-ow and is cooled greatly.
The storage mass is therefore heated. The
local temperature efciency, i.e. directly
at the inlet to the warm air, is very high.
Condensation can also occur very easily.
Mid warm air
The wheel duct now has passed half of
its time in the warm air. The storage mass
has been heated by the owing warm air;
therefore, the warm air is not cooled down
as much as in entry inlet zone. The wall
temperature at the entry and exit is approxi-
mately the same. Condensation occurs only
with large humidity differences.
Warm air exit
The wheel duct is now shortly before entry
to the cold air. It has virtually reached the
temperature of the extract air at the entry
side. The transferred performance is still
only low.
The dwell time in the warm air and in the
cold air, i.e. the speed of rotation, is deci-
sive for the performance of the rotary heat
exchanger. It depends on the storage mass
(thickness, geometry), the heat transfer and
the air velocity.
Cold air exit
The wheel duct has passed through the
cold-air section. The storage mass has
greatly cooled, almost down to the cold-air
temperature in the entry section. After
crossover to the warm air side, the cycle
starts anew.
Mid cold air
Half of the dwell time in the cold air is past.
The storage mass has already cooled
signicantly. The temperatures at the entry
and exit are approximately equal.
Cold air entry
After the transition from the warm air to the
cold air, the wheel duct now has cold air
owing through in the opposite direction
(referring to the temperature). With the
high temperature difference the transferred
performance is very high, i.e. the cold air is
very strongly heated; in reverse the storage
mass is strongly cooled. Any conden-
sate formed on the exchanger surface is
(partially) absorbed by the heated cold air.
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Principle and Operation

4
1.2 Humidity transmission
In addition to heat, humidity can also be transported with
rotary heat exchangers. The decisive factor here is the mate-
rial and/or the surface of the storage mass. Characteristic
features for different designs have been developed with
detailed measurements of wheels from different manufac-
turers by the building technology test centre of the University
of Lucerne. The reference factor for the humidity efciency
is the condensation potential; that is the humidity difference
between warm-air humidity and the saturation humidity of the
cold air (see Fig. 4).
Fig. 4: Denition of condensation potential κ
Sorption wheel
Enthalpy wheel
Condensation wheel
Warm air entry
Cold air entry
Saturated cold air
Condensation potential of
warm air κ
Humidity efciency ηx
0
0.2
0.4
0.6
0.8
0.9
1.0
0.7
0.5
0.3
0.1
-4 -2 0 2 4 6 8 10
Condensation potential κ [g/kg]
The following must be noted:
■ The greater the condensation potential the greater the
volume of condensate that can be expected at the warm
air side.
■ If the condensation potential is zero or negative, no
condensation can take place. Humidity transmission is
therefore only possible by sorption.
■ The derived characteristics reect typical values of 1 : 1
for the mass-ow ratio and the pressure drop of approx.
130 Pa at an airway height of 1.9 mm.
■ The area of application of reference magnitude κ, i.e. the
condensation potential, is restricted to the standard condi-
tions of ventilation technology. The temperature efciency
must be at least 70 %. The humidity transmission must
not be restricted by the saturation curve (e.g. with very
low outside temperatures).
Fig. 5: Typical course of humidity efciencies of various
wheels depending on the condensation potential
Temperature
WaterRelative humidity
Principle and Operation

5
There are 3 different designs:
Condensation wheel
The storage mass consists of smooth, untreated aluminium,
which only transmits humidity if condensation occurs on the
warm-air side and it is picked up by the cold air (partially).
Humidity efciency rates greater than 80 % can be reached if
the temperature difference is high.
The use of condensation wheels for heat and humidity trans-
mission is recommended primarily for ventilation systems
without mechanical cooling, i.e. for winter operation.
Enthalpy wheel (hygroscopic wheel)
The metallic storage mass has been treated to form a capil-
lary surface structure. The humidity is transmitted by sorption
and condensation, with the sorption component being very
low. Humidity transmission in summer operation (κ < 0) is
also very low.
Sorption wheel
The storage mass in this case has a surface that transmits
humidity by pure sorption (i.e. without condensation). The
humidity efciency is therefore virtually independent of the
condensation potential. The low decrease can be explained
with the simultaneous reduction of the temperature differ-
ence.
Sorption wheels are recommended particularly in systems
with mechanical cooling. The high humidity efciency, even
under summer conditions, dries the fresh air. This requires
less cooling capacity and reduces energy costs for cooling
up to 50%.
1.3 Leakage of rotary heat exchangers
Rotary heat exchangers transfer heat and humidity via a
rotating storage mass that alternates between the exhaust
air and supply air ows. This functional principle delivers
extremely efcient energy recovery, but it does also entail a
certain leakage: the exhaust air and supply air ows cannot
be completely separated from one another. The seals are
not able to withstand the existing differential pressure with
100 percent effectiveness. The rotating storage mass trans-
fers a small quantity of air from one air ow to the other on
every rotation (carryover).
The effects of the leakage must be taken into account during
planning and conguration of air handling systems. The draft
standard EN 13779:2014 consequently denes the calcula-
tion method for the leakage. It describes the following two
values:
■ Exhaust air transfer ratio EATR
This is the quantity of exhaust air that enters the supply
air due to carryover and seal leakage.
■ Outdoor air correction factor OACF
This is the ratio between the quantity of the fresh air and
supply air ows.
These two values are calculated using the design program
for a differential pressure to be specied between the supply
air and extract air (Δp2 2 -11). From April 2015, this calcula-
tion will be mandatory for Eurovent-certied rotary heat
exchangers.
Based on the calculated leakage values, it is possible to take
suitable measures according to the application. The following
must be noted:
■ The transfer from exhaust air to supply air can be signif-
icantly reduced or even completely eliminated by taking
the following measures:
– Using a purge sector
– Suitable arrangement of fans (supply air pushes,
exhaust air sucks)
■ The OACF value is decisive for setting the dimensions of
the fans:
– An OACF value greater than 1 means that fresh air
gets to the exhaust air side (due to seal leakage and/
or purge air). The size of the supply air fan will have to
be increased accordingly to ensure that the required
air volume is supplied to the building. This means more
energy is required for pumping the air.
– An OACF value less than 1 means air is moving in the
opposite direction, i.e. there is a proportion of recircu-
lated air in the supply air.
Denition of leakage according to EN 13779:2014 (draft)
Exhaust air transfer ratio:
a22 – a21
EATR =
a11
(Exhaust Air Transfer Ratio)
a22 ....... Concentration in supply air
a21 ....... Concentration in fresh air
a11 ....... Concentration in extract air
Outdoor air correction factor:
qm 21
OACF =
qm 22
(Outdoor Air Correction Factor)
qm 21 ..... Mass ow of fresh air
qm 22 ..... Mass ow of supply air
Principle and Operation

6
1.4 Frost limit
If the warm extract air stream is very strongly cooled conden-
sate can be formed and it may even freeze. The fresh air
temperature at which this starts is referred to as the frost
limit.
■Condensation wheel, enthalpy wheel: The condensate
generated by cooling the extract air may freeze at low
outside temperatures. There is a frost hazard at equiva-
lent mass ows for exhaust air and fresh air if the average
inlet temperature of the two air streams is less than 5 °C.
tm = t11 + t21
2 < 5 °C
■Sorption wheel: The gaseous humidity transmission by
sorption generally prevents condensation; the frost hazard
is reduced.
1.5 Temperature efficiency
Appropriate design and serial layout allows virtually any
temperature efciency to be reached. The 'correct' temper-
ature efciency depends on the applicable regulations and
the economy calculations, i.e. the operating data such as
energy price, service life, operation time, temperatures,
maintenance requirements, interest etc. Even minor changes
(a few percent lower temperature efciency, a few pascals
more pressure drop) can mean signicantly poorer results for
capital value and amortisation period.
1.6 Pressure drop
Heat recovery units cause pressure drop on the extract
and supply air sides and as a result operating costs. With
current general conditions the economical values for wheels
are between 80 Pa and 130 Pa. However, to reduce costs,
more and more heat recovery units whose pressure drops
are above these economically reasonable values are being
installed. This affects the feasibility of the system.
1.7 Pressure difference
A distinction is made between internal pressure difference
(between exhaust air and supply air) and external pressure
difference (between the exchanger and the environment).
Internal pressure difference:
The internal leakage between the two air streams depends
greatly on the pressure difference. Hoval rotary heat
exchangers with high tightness seal compared with other
designs are certainly very leak-proof, but the following infor-
mation should be taken into account in the design:
■The pressure difference in the rotary heat exchanger
should be as low as possible.
■In applications that involve the danger of odours the pres-
sure gradients and therefore possible leakage from the
fresh air to the exhaust air must be considered.
However, the internal pressure difference may also cause
deformation of the casing; a pressure difference of more than
2000 Pa is not permitted.
Notice
The pressure difference depends on the layout of the
fans. Overpressure on one side and underpressure
on the other side add up.
External pressure difference:
This is a major factor for the external leakage of the heat
exchanger. If a duct system is correctly and carefully
installed, this effect can be ignored.
1.8 Hygiene
Hoval rotary heat exchangers with high tightness seal have
been tested for conformity with hygiene requirements at the
Institute for Air Hygiene in Berlin. The test criteria were the
requirements relevant to hygiene for applications in general
building ventilation and in hospital applications. All hygiene
requirements were met.
Notice
Hoval rotary heat exchangers are tested and certi-
ed for operation in hospitals in accordance with
DIN 1946-4. Install rotary heat exchangers with the
'coated casing' option for such applications.
Fig. 6: Certicate of
hygiene conformity test
(valid for Hoval rotary
heat exchangers with high
tightness seal)
Principle and Operation

7
1.9 Reliable data
Hoval rotary heat exchangers are always tested by inde-
pendent test organisations (e.g. at the building technology
testing laboratory of the University of Lucerne). All technical
data are based on these measurements. This means that
they are reliable data for planners, installers and operators.
Relative humidity efciency
0510 15 20 25
0 %
20 %
40 %
60 %
80 %
100 %
Speed of rotation [rpm]
Fig. 8: Dependency of the humidity efciency on the rotational speed
Relative temperature efciency
0510 15 20 25
0 %
20 %
40 %
60 %
80 %
100 %
Speed of rotation [rpm]
Fig. 7: Dependency of the temperature efciency on the rotational speed
2 Performance control
The Hoval rotary heat exchanger always operates as a
temperature rectier between the two air streams. The
ow direction of the heat is irrelevant in this context, i.e.
depending on the temperature gradients between extract
air and fresh air either heat or cold is harvested. Therefore,
regulation of the output of the Hoval rotary heat exchanger
is not necessary if the extract air temperature is identical to
the setpoint temperature. In this case, the fresh air is always
either heated or cooled in the direction of the set temperature
by the heat exchanger.
However, in most cases there are heat sources in the
ventilated rooms (people, machines, lighting, solar radiation,
processing systems) that increase the room temperature,
i.e. the extract air temperature is higher than the setpoint
temperature. In this case, check the outside temperature
from which the system is heated at full performance of the
rotary heat exchanger and – if this cannot be tolerated – the
performance of the heat exchanger must be controlled.
It is very simple and economical to reduce the performance
of the rotary heat exchanger for heating and also for humidity
transmission by reducing the speed of rotation. All Hoval
rotary heat exchangers can therefore be supplied with
speed-controlled drives.
There is also the option of diverting one or both air streams
past the wheel by a bypass. The method – used primarily in
process technology and at various air ow rates – must be
installed by the customer.
Performance control

8
3 Structure
A functional rotary heat exchanger consists of the wheel, the
casing and the drive.
3.1 Wheel
Storage mass
A corrugated and a smooth metal foil are wound together
as the storage mass. This forms triangular, axial ducts. The
material is 60 µm thick.
The surface treatment also depends on the use; there are
3 series:
■Series A: condensation wheel, consisting of high-quality
aluminium.
■Series E: enthalpy wheel, consisting of aluminium with
enthalpic coating.
■Series S: sorption wheel, consisting of an aluminium
substrate foil coated with a sorption substance (e.g. silica
gel) for humidity transmission. This transmits humidity in
the form of a gas without condensation.
Fig. 9: A corrugated and a
smooth metal foil are wound
around each other.
Fig. 10: Production on state-
of-the-art machines ensures
consistently high quality.
Fig. 11: Large wheels are cut
into several segments.
Design
The depth of the wheel is 200 mm. The wheel is stabilised by
double spokes, screwed (and welded) to the hub and welded
to the wheel mantle (see Fig. 12). This guarantees a long
service life.
For stability and performance large-diameter wheels must be
made in a segmented design. The diameter of the wheel can
be freely selected in 10-mm steps.
The outside of the wheel is held together by an aluminium
jacket plate (welded). This guarantees uninterrupted radial
runout and enables maximum usage of the wheel surface.
Hub with inner bearing
The hub, whose size depends on the wheel diameter, is
xed to the axle with 2 internal ball bearings. It is fastened
to the crossbars of the casing. This design has the following
advantages:
■The internal bearings are protected against contamination
and require little space.
■The axial lock with circlips makes installation and removal
quick and simple.
■Both bearings are integrated into the hub, i.e. in the
same component. This ensures that they mesh together
perfectly (in contrast to external bearings). This does not
reduce the service life of the bearings.
■The position of the axle, hub and wheel is precisely xed
by the fastening of the internal ball bearings by the hub
and the circlips.
■The xed axles connects the two crossbars of the casing.
This greatly increases its stability.
Fig. 12: The wheel is permanently stabi-
lised by internal welded double spokes.
Fig. 13: Hub with long-life, permanently
lubricated inner bearing
Structure

9
3.2 Casing
There are different casing designs, depending on the wheel
diameter and whether the wheel is 1-piece or segmented.
Sheet-metal casing
Self-supporting aluzinc sheet steel casing are standard for
1-piece wheels with diameters up to 2620 mm. The sheet-
metal casing is strengthened with galvanised steel proles
from wheel diameters of 1800 mm.
Prole casing
A prole design of aluminium is used for wheels above
1500 mm diameter. The casing is extremely stable and the
dimensions are exible. The plate covers can be removed
and replaced quickly and easily, a factor which is important
for installation of segmented wheels.
The height and width of the prole casing is limited to 4.2 m.
Larger casings (welded construction, galvanised) are avail-
able customised for specic systems.
The casings are designed for installation in a ventilation unit.
Therefore, the sides are open; this allows inspection and
maintenance as required.
Wheel diameter (in mm)
Wheel 1-piece
Sheet-metal casing
(Delivery assembled)
Wheel 4-piece
Prole casing
(Delivery in parts)
Wheel 8-piece
Prole casing
(Delivery in parts)
Required torque 500 Nm
400 Nm
300 Nm
200 Nm
100 Nm
0 Nm
Table 1: Overview of designs and wheel dimensions (for standard casing)
600
1500 2500 2620 3800 5000
Casing types
Different types of casing are also available for adaptation to
different installation situations (see also Section 4 'Options'):
■ Special size:
Height and width of the casing can be selected as
required (for example for adjustment to the internal
cross-section of a ventilation unit). The hub can also be
placed away from centre.
Notice
The casing design may be different for special
sizes compared to Table 1.
■ Duct design:
The side walls of the casing are closed (for the duct
connection).
Structure

10
3.3 Peripheral slide seal
High tightness seal
■ In rotary heat exchangers with sheet-metal casing auto-
matically adjustable constant-force springs are mounted
on the wheel mantle; they press the abrasion-resistant
slide seal against the casing. The patented system perma-
nently minimises leakage and allows the unit to be sized
for smaller air ow rates.
■ In the prole casing a ring seal with externally accessible
double springs is used. They press the seal to the casing
and to the wheel.
Basic tightness seal
■ In rotary heat exchangers with sheet-metal casing, sealing
strips are mounted on the wheel mantle (e.g. brushes).
These guarantee the minimal sealing effect for the air
ows that is usual for devices on the market.
Fig. 14:
High tightness seal
Fig. 15: Peripheral slide
seal in prole casing
Fig. 16:
Basic tightness seal
3.4 Transverse seal
The transverse seal between the two air streams consists of
adjustable aluzinc sheet steel with a triple rubber-lip seal.
3.5 Drive
The wheel is driven by an electric motor and belt. The motor
is generally fastened on the left or right on a rocker in the
casing. Because manufacturers of ventilation units and
installers sometimes install their own drive, Hoval offers this
component as an option.
2 versions are available:
Constant rotational speed
The motor is switched on and off by a single switch or
contact. Output regulation (i.e. changing the temperature
efciency or humidity efciency) is not possible.
Controllable rotational speed
The drive motor is controlled by a control unit. A frequency
converter (FU) is generally used. Common additional func-
tions are speed monitoring (by inductive sensors) and inter-
mittent operation. If heat recovery is not required, the wheel
is moved slightly at intervals to prevent dirt build-up.
The control unit and as a result the wheel are normally actu-
ated by the room temperature controller, for which the rotary
heat exchanger is perceived as an energy resource for both
heating and cooling, which forms part of the cascade control
concept.
Structure

11
4 Options
4.1 Drive
The wheels are driven by a worm gear or a spur-gear drive
motor using a v-belt; the type and size of the motor depends
on the wheel diameter:
■ Drive Y
for direct drive by mains power. On/Off operation at
constant speed only.
■ Drive A
The motor speed and therefore the performance of the
rotary heat exchanger can be controlled. A control unit
(option R) is required.
Motor designation A 60 A 250 A 370 A 750
Motor power kW 0.06 0.25 0.37 0.75
Output shaft mm 18 x 34 20 x 55 20 x 65 25 x 60
Current Y (direct operation by mains power) A 0.25 0.83 1.09 1.92
Current Δ (with control unit) A 0.30 1.44 1.90 3.40
Protection rating Drive Y –IP 44 IP 55 IP 55 IP 55
Drive A –IP 54 IP 55 IP 55 IP 55
Motor nominal speed n1min-1 1600 1320 1380 1400
Output speed n2at 50 Hz min-1 100 132 138 140
Motor nominal torque m1Nm 0.5 1.81 2.60 5.10
Output torque m2Nm 6.1 14 21 45
Rotor diameter mm up to 1300 up to 1800 up to 2620 up to 3800
Control unit Type R / 370 R / 370 R / 370 R / 750
Table 2: Data sheet for rotary drives
Options

12
4.2 Control unit
Structure
A frequency converter with a modular design is used as the
control unit; it can adjust the speed of three-phase motors
innitely. Protection rating IP 54 is required for installation in
the ventilation unit. The power unit is protected from under-
voltage, overvoltage or non-approved converter temperature.
The aluminium casing and the standard input and output
lters increase the immunity to interference. Error messages
can be read out directly at a ashing LED.
The control unit is delivered ready for operation with the
factory-set parameters. Various settings can be changed with
an optionally available operating unit.
Function
■The control unit can be used for condensation, enthalpy
and sorption wheels that require speed control. All
standard control signals are accepted.
■A quadratic (standard) or linear implementation of the
setpoint into the rotary eld frequency based on the
maximum frequency of the selected parameter set is
used.
■As soon as the input signal is below the dened threshold
value, the wheel stops rotating. After an adjustable holding
time intermittent operation is started and the wheel rotates
at the dened speed for a few seconds.
■An inductive sensor can be connected for speed moni-
toring (option D).
■Readiness for operation and any fault messages can be
output via a relay.
System design
■The control unit is not designed for outside installation.
■The control unit is normally installed in the side wall of the
casing.
■The normal installation position is vertical. Sufcient venti-
lation for heat dissipation is essential.
Fig. 17: Control unit R
Installation
Caution
All work for transport, installation and commissioning
as well as maintenance is conducted by qualied
technicians (note IEC 364 and VENELEC HD 384 or
DIN VDE 0100 and IEC Report 664 or DIN VDE 0110
and national occupational health and safety regula-
tions or VGB 4).
Qualied technicians as dened by the basic safety instruc-
tions are persons who are familiar with the setup, installation,
commissioning and operation of the product and are appro-
priately qualied for their activities (dened in IEC 364 or DIN
VDE 0105).
Commissioning
■Before commissioning the control unit the rotary heat
exchanger must be operating correctly.
■The direction of rotation of the wheel can be changed by
reversing 2 phases of the motor.
■A green LED lights when the unit is operating without
faults.
■Causes of faults are displayed on the control unit.
Options

13
R/370 (Type: F-D 370-WT VECTOR IP54)
R/750 (Type: F-D 750-WT VECTOR IP54)
7
1
2
3
4
5
6
8
9
10
11
12
13
14
15
16
17
18
19
B1
10k
+10 V reference voltage
Analogue setpoint input
GND (analogue)
Analogue output
+15 V (max. 100 mA)
Start clockwise
External sensor
Priority speed
Parameter set switching
Release
GND (digital)
Relay output 1 (normally open contact)
Relay output 1 (changeover contact)
Relay output 1 (normally closed contact)
PTC motor temperature monitoring
PTC motor temperature monitoring
Relay output 2 (normally open contact)
Relay output 2 (changeover contact)
Relay output 2 (normally closed contact)
Terminals 1, 2, 3 Connection of control signal
Terminals 5, 7, 11 Connection of inductive sensor for speed monitoring
Terminal 6 Start of wheel (terminal 10 must be under power)
Terminal 9 not under power Sorption wheel operating mode
Terminal 9 under power Condensation/enthalpy wheel operating mode
Terminal 10 Reset-function by short-term voltage cut-off,
acknowledgements of faults
Terminals 15, 16 Connection of thermal contact from motor
Terminals 17, 18, 19 Potential-free output for output of faults via relay
Table 3: Circuit diagram of control inputs for control units
R/370 R/750
Output motor-side Max. motor power kW 0.37 0.75
Nominal output current A 2.2 4.0
Max. output voltage V 3 x 230 3 x 230
Output frequency Hz 0..500 0..500
Mains input Rated voltage V 230 230
Mains frequency Hz 50/60 50/60
Fuses A T 6 8
General data Protection rating IP 54 IP 54
Ambient temperature °C 0..40 0..40
Air humidity % 20..90 20..90
Power dissipation W 35 45
Dimensions H x W x D mm 282 x 112 x 70 282 x 112 x 70
Table 4: Technical data for the control units
Options

14
4.3 Operating unit
The control unit settings can be customised with the oper-
ating unit. Parameters can be congured quickly and easily
with the LCD graphical display, the menu structure in
German or English and the parameters displayed in plain
text.
Fig. 18: Operating unit
4.4 Rotational speed monitoring
The speed of rotation of the wheel can be monitored with an
inductive sensor. Stoppages, e.g. caused by a broken v-belt,
can be detected quickly and the cause can be corrected.
4.5 Inspection cover
The motor and the v-belt can be inspected through inspec-
tion covers on both sides. This is recommended if inspection
from the side is not possible.
Notice
Inspection covers cannot always be installed in small
casing dimensions. If applicable, this is shown in the
Hoval CASER design program. Detailed information
can be obtained from Hoval's application consulting
service.
4.6 Purge sector
When correctly laid out, the purge sector reduces the
transmission of extract air to the supply air. The size can be
congured individually to reduce the purge and energy loss
to a minimum.
Instructions for the optimum settings can be found in
Section '7.6 Using and setting the purge sector'.
Factory setting: 3°
Fresh air
Exhaust air
Fig. 19: Purge sector
4.7 Duct design
The side walls of the casings in Hoval rotary heat
exchangers with ducts are enclosed. This makes them suit-
able for the duct connection.
4.8 Coated casing
Hoval rotary heat exchangers with coated casings are avail-
able for applications with very high hygiene requirements
(e.g. hospitals): powder-coated red (RAL 3000).
4.9 Offset wheel position
The hub can be offset for optimum adjustment to the installa-
tion situation (such as installation in a ventilation unit).
Options

15
5 Dimensions of the exchangers
The minimum size of the casing depends on the wheel diam-
eter. The external dimensions can be individually adjusted.
A
B
290
70
30
60
Casing dimensions min. max.
Dimension A Ø + 80 1350
Dimension B Ø + 80 1350
Table 5: Dimensional drawing for small sheet-metal casing (dimensions in mm)
A
B
320
100
45
80
Casing dimensions min. max.
Dimension A Ø + 80 2850
Dimension B Ø + 80 2700
Table 6: Dimensional drawing for large sheet-metal casing, wheel diameter up to
1800 mm (dimensions in mm)
A
B
430
70
70
70
Casing dimensions min. max.
Dimension A Ø + 200 4200
Dimension B Ø + 200 4200
Table 7: Dimensional drawing for prole casing (dimensions in mm)
A
B
320
40
45
40
Casing dimensions min. max.
Dimension A Ø + 80 2850
Dimension B Ø + 80 2700
Table 8: Dimensional drawing for large sheet-metal casing, wheel diameter from
1800 mm (dimensions in mm)
Dimensions of the exchangers

16
6 Unit type reference
AV- A 1 - 0600 / 1.4 / A0680B0680 /S001 / A1 , RN, B , D , SR, I3, K , AX1234BX1234
Air ow
Case A, B, C or D
Installation position
V Vertical to 20% inclination
H Horizontal
Peripheral slide seal
- High tightness seal
B Basic tightness seal
Rotor model
A Condensation wheel of aluminium
E Enthalpy wheel with enthalpy coating
S Sorption wheel with sorption coating
Wheel construction and casing design
1 Wheel 1-piece, sheet-metal casing, supplied assembled
4 Wheel 4-piece, prole casing, supplied unassembled
8 Wheel 8-piece, prole casing, supplied unassembled
Wheel diameter (in mm)
Any required size in steps of 10 mm
Airway height
1.4 mm
1.6 mm
1.9 mm
2.9 mm
Casing size in mm
Dimension A x dimension B
Any required size in steps of 1 mm
Special code
---- Standard
Unit type reference

17
AV- A 1 - 0600 / 1.4 / A0680B0680 /S001 / A1 , RN, B , D , SR, I3, K , AX1234BX1234
Drive
-- Without drive
A Drive controllable
Y Drive for constant speed of rotation (direct drive from mains power)
1…3 Species the position
Control unit
-- Without control unit
RN Control unit, supplied uninstalled
Operating unit
- Without operating unit
B Operating unit in German
O Operating unit in English
Rotational speed monitoring
- Without rotational speed monitoring
D Rotational speed monitoring
Purge sector
-- Without purge sector
SR Purge sector, mounted in position for clockwise direction of rotation
SL Purge sector, mounted in position for anticlockwise direction of rotation
SN Purge sector, supplied uninstalled
Inspection cover
-- Without inspection cover
I Inspection cover
1…3 Species the position
Casing model
- Standard
K Duct design
C Coated casing
Offset
------------ Standard
AX Distance of casing edge to wheel axle in dimension A
BX Distance of casing edge to wheel axle in dimension B
Unit type reference

18
7 System design
7.1 Hoval CASER design program
The Hoval CASER design program is available for fast
and accurate design of Hoval rotary heat exchangers
(= Computer Aided Selection of Energy Recovery). It runs
under Microsoft® Windows and offers the following applica-
tions:
■ Secure planning with Eurovent and TÜV-certied data
■ Accurate calculation of a specic Hoval rotary heat
exchanger
■ Calculation of all applicable rotary heat exchangers for a
specic project
■ Calculation of the efciency class in accordance with
EN 13053
■ Calculation of leakage in accordance with Eurovent
■ Price calculation for the selected rotary heat exchangers
Notice
You can download the Hoval CASER design program
free of charge from our home page (hrs.hoval.com).
The program is also available as a Windows DLL le and can
therefore be integrated into other spreadsheet programs (on
request).
Hoval CASER
7.2 Design data
As with all design, achieving the setpoint values depends
on the correct starting data. This often causes problems,
particularly in ventilation applications. The reason is the
dependence of the temperature of the specic density and
the specic heat. Water vapour in the air is also very impor-
tant for the design. This is why the data available on entry to
the exchanger are essential for accurate calculation of a heat
exchanger.
Exhaust air
stream
Extract air owrate V11 [m3/s]
Extract air temperature t11 [°C]
Extract air rel. humidity RH11 [%]
Supply air
stream
Fresh air owrate V21 [m3/s]
Fresh air temperature t21 [°C]
Fresh air rel. humidity RH21 [%]
Table 9: Design data
The following errors must be avoided with data recording:
■ Volume ow is not equal to mass ow. The mass ows
of supply air and exhaust air must be known for correct
design.
■ The humidity in the extract air is generally estimated too
high, particularly for winter operation. (Where does the
humidity come from?)
■ Are the temperatures (fresh air, extract air) really as stated
in practice (or are they wishful thinking)?
7.3 Local conditions, installation position
■ Where should the heat recovery unit be installed?
■ Which is the optimum air path?
■ What dimensions are approved?
Notice
Please note that the wheel must be accessible for
maintenance and cleaning. Hoval therefore recom-
mends to provide 600 mm free space in front of and
behind the wheel (= width of an inspection door).
7.4 Wheel type
The wheel type must be selected depending on the applica-
tion. The following are recommended:
■ The condensation or enthalpy wheel is suitable for venti-
lation systems without mechanical cooling and without
humidity control.
■ Sorption wheels are recommended for ventilation systems
with mechanical cooling. The high humidity efciency,
even under summer conditions, dries the fresh air. This
requires less cooling capacity and reduces energy costs
for cooling up to 50%.
System design