The document summarizes the technical specifications of the EUKN Combi Cooler air handling unit. The Combi Cooler integrates a liquid cooler, supply air coil, and chilled beam circuit to provide both heating and cooling of supply air and chilled water production. It uses higher water temperatures than traditional systems to improve efficiency. Calculations are provided to estimate the required cooling power based on supply air flow, extract air flow, and total area to be cooled by chilled beams. The Combi Cooler includes an auxiliary liquid-cooled condenser to handle excess condenser load if needed.

1. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
The Combi Cooler is a ready-to-install functional part
with an internal cabinet for all control and safety appara-
tus. Only the electrical power supply and the control sig-
nals required from superordinate control systems need be
connected to the installation site.
See separate table and diagram.
Each Combi Cooler is factory tested and the test re-
port is included in the delivery.
Intended use
The Combi Cooler is most appropriate where room-based
cooling is carried out using chilled beams and the cool-
ing power is a maximum of 50 W/m2. In general this
cooling power is sufficient in normal office and business
premises.
Energy efficiency
In traditional solutions the supply air temperature is 15 -
16° C, while in the Combi Cooler it is 18 ° C. Because the
supply air temperature is slightly higher, areas such as
empty meeting rooms maintain a comfortable tempera-
ture with no heating load.
Principles of operation
Energy is also saved because the room temperature
The EUKN Combi Cooler is a liquid cooler from Fläkt does not drop by much. In addition, energy intensive for-
Woods which is integrated into the air handling unit. It is mation of condensation in the supply air coil is avoided.
optimised for use in conjunction with a chilled beam sys- There is a substantial difference between energy con-
tem. The Combi Cooler cools water which is then used to sumption for supply air at 18°C and 15°C, see Diagram 1
cool supply air and a chilled beam circuit. below.
The Combi Cooler can also produce cold water for the However, this is not all a real reduction of consump-
chilled beam circuit at the same time as it heats the sup- tion, because the chilled beams must cool more to com-
ply air using heat from an external system pensate for the hotter supply air.
Functions Energy consumption, supply air
1) Controlling the supply air temperature: both heating Temperature, °C
and cooling. 28
2) Produces cold water for an internally mounted sup- 26
ply air coil. 24
22
3) Produces cold water for room-based cooling.
20
Room-based cooling is carried out either using chilled 18
4900 kWh
beams, fan convectors or cassette chilled beams. The 16
Combi Cooler has a supply air coil that operates as a 14 12 000 kWh
heating coil as well as a cooling coil. The integrated shunt 12
group regulates heating or cooling to the supply air coil Supply air cooling, Supply air cooling,
to 18 °C to 15 °C
as necessary. The network of chilled beams is connected
by its own pipes to the Combi Cooler, which produces
cold water for them. Energy necessary to cool the supply air.
When using the Combi Cooler, all refrigeration com- Diagram 1. Annual reduction of energy consumption.
ponents are installed in the plant room. No separate liq-
uid coolers or roof-mounted condensers are needed with
the Combi Cooler. Because these are not needed, exter-
nal condenser pipes and their pumps need not be routed
to the roof. Because the appearance of the building is not
changed, renovation is easier, and at the same time noisy
condenser fans are not needed.
Fläkt Woods 8733 GB 2009.05 1 Specifications are subject of alteration without further notice.

2. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Water temperature
Considering the cooling efficiency factor, it is better to If a lower supply air temperature is desired, a water
produce the cooling power at a higher water tempera- temperature lower than 12°C can be used. In this case the
ture. Systems using the Combi Cooler utilise significantly cooling power is reduced somewhat because the cooling
higher water temperatures than traditional systems using efficiency factor drops, see the cooling power table over-
liquid coolers. leaf.
The nominal cooling power of the Combi Cooler is Internal configuration and the choice of components
designed for a water temperature of 12/18°C. At this are of great importance for the cooling unit’s cooling effi-
water temperature a supply air temperature of 18°C is ciency factor. The evaporators in the Combi Cooler have
achieved. been designed with an exceptionally large surface area;
Thanks to this higher water temperature, the evapo- as a result of this, the minimum possible temperature dif-
ration temperature in the cooling unit is higher, which ference is achieved between the evaporation temperature
means that the cooling efficiency factor increases. Raising and the temperature of the water leaving the evaporator.
the water temperature from the normal 7°C to 12°C im-
proves the cooling unit’s cooling efficiency factor by ap-
proximately 20%. The annual consumption of electrical
energy for cooling is reduced proportionately.
Subcooling refrigerant
5
01 020 30
50,00
R134a 0,0 0,0 0,00 0,0040 0,0050 0,0060
100
100 0,0070
40,00 0,0080
90
0
0,0090
1,7
90
0,010 The supply air’s need for cooling
80
30,00
s=
80
power: P = qv x 8.4 kW/( m3 x s)
70
020 70
0,0 0 0,015
20,00 v= 03
60
0,0 60
v= 0,020
040
where
50
0,0 50
v= 0
0 ,006
v= 0,030
40
40
qv = unit air flow [m3/s]
10,00
9,00 080 0,040
30
0,0 10 30
8,00 v= 0,0
v=
5
1,7
0,050
5
7,00
0
5
0
1,9
20
1,9
1,8
1,8
20
s=
6,00 0,060
0
s=
15
2,0
s=
s=
s=
0,0 0,070
5,00 v=
Cooling power per 1 m3/s air is 8.4
s=
10
10 0,080
20
4,00 0,0 0,090
5
v=
2,0
0,10
0
kW.
0
s=
,03 0
3,00 v=
0
0
,040
2,1
At an air flow of 2 litre/(s x m2),
–10
v=
0 0,15
–10
s=
2,00
5
2,1
0
0,06 0,20
the surface area of a 1 m3/s air flow
v=
–20
s=
0
,080 –20
2,2
v=0
,10 0,30
is 500 m2.
s=
v=0
–30
1,00
25
0,90 –30 0,40
2,
15
v = 0,
The supply air’s consumption
s=
0,80 20
v = 0, 0,50
0,70
–40
0,60 0,60
0,50
x = 0,10 0,20 0,30 0,40 0,50 0,60 0,70 0,80 0,90
–40
–40 –20 0 20 40 60 80 100 120 140 160
of cooling power W/m2 is thus 8.4
140 160 180
s = 1,00
200 220
1,20
240 260
1,40
280 300 320
1,60
340 360 380 400 420 440 460 480 500 520 540 560
kW/ 500 m2 = 17 W/m2.
2) Room-based cooling
Configuring and selecting Estimating the required The design basis room temperature
in this example in summer is 25°C.
a model with the required cooling power Swedish Indoor Air Classification
output This method is used to provide a 2008 allows higher room tempera-
When configuring the cooling rough estimate. ture values than this, for class S2
power of the Combi Cooler, the More accurate calculations can be 27°C and for class S1 26°C, calcu-
base value of the air flow is 2.0 li- carried out using the ACON air lated as a mean of the offset over
tre/(s x m2). This provides a cooling handling unit selection program. one hour.
power of 50 W/m2. Room-based cooling consists
1) Cooling the supply air
If the air flow is lower, the maxi- of cooling power from supply air
mum cooling power is also lower. The supply air is cooled from 25°C along with liquid-borne supplemen-
In this case the extract air flow to 18°C. tary cooling.
is crucial, as the heat arising dur- The necessary cooling power in that The air-borne cooling power is
ing cooling is released into the ex- case is: 1 x 1.2 x (25 – 18) = 8.4 kW 17 W/m2 as above.
tract air. The mean water-borne cooling
where
power is 35 W/m2.
1 = air flow [m3/s] Consequently, the total room-
1.2 = air density [kg/m3] based cooling power is 52 W/m2.
Fläkt Woods 8733 GB 2009.05 2 Specifications are subject of alteration without further notice.

3. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Calculation of the total power requirement for all rooms
P = 35 W/(m2 x A) 45 000
where 40 000
A= total area of rooms equipped with chilled beams. 35 000
Cooling power, W
30 000
25 000
Example 20 000
Supply air flow = 2.6 m3/s 15 000
Extract air flow = 2.4 m3/s 10 000
Ventilation area = 1300 m2 5 000
Area equipped with chilled beams = 900 m2 0
0 2 000 4 000 6 000 8 000
Accumulated cooling power requirement
Supply air cooling power
2.6 m3/s x 8.4 kW/(m3 x s) = 21.8 kW The figure shows a calculation of the cooling power requirement for
a floor in a VVS-2000, Swedish water supply, heating and sanitation
Chilled beam circuit cooling power 900 m2 x industry organization, type building. It shows that a cooling power
35 W/ m2 = 31.5 kW above 75 % only needs approximately 5% of the operating time.
Total cooling power = 53.3 kW
Checking the sufficiency of the extract air When designing the air flow, the target should be that
flow the greatest possible proportion of the building’s extract
air goes via heat recovery. This improves the building’s
At a cooling power of 21.8 kW, the approximate total energy efficiency because less air is blown out into
condenser power will be 25 kW/(m3 x s). This heat the surrounding environment without undergoing heat
output must be removed with the extract air. recovery.
The necessary extract air flow in this example When a rotary heat exchanger is used the proportion
will be 53.3 kW/ 25 kW/(m3 x s) = 2.13 m3/s. of extract air in line with class 3 has been limited to 5%
The extract air flow in the example is 2.4 m3/s, (toilets, washrooms, saunas). In line with class 2, the ex-
i.e. the extract air flow is sufficient. tract air can be connected without restriction (canteens,
business premises, storage spaces in office buildings,
changing rooms, and non-smoking restaurants).
Liquid-cooled auxiliary condenser Unit Power Air flow Maximum Cooling power Cooling power
In some cases the calculation can show that the extract size model m3/s cooling supply air chilled beams
air flow is too small to remove sufficient condenser heat. power kW kW kW
This can be the case even if the model with the greatest EU-21 1 0.8-1.4 23 7.1-20.6 2.4-15.9
EU-21 2 0.8-1.4 30 7.1-20.6 9.4-22.9
power has been selected.
EU-21 3 0.8-1.4 36 7.1-20.6 15.4-28.9
However, the Combi Cooler consists of a water-borne
EU-22 1 1.2-1.8 33 10.4-26.6 6.4-22.6
auxiliary condenser which is activated in the event of
EU-22 2 1.2-1.8 39 10.4-26.6 12.4-28.6
overloading and deals with some of the condenser load.
EU-22 3 1.2-1.8 46 10.4-26.6 19.4-33.6
The power of the auxiliary condenser is governed by a
EU-31 1 1.6-2.8 46 13.7-41.5 4.5-32.3
pressure-actuated water valve which automatically gov- EU-31 2 1.6-2.8 57 13.7-41.5 15.5-43.3
erns the necessary condenser power. The inlet to the aux- EU-31 3 1.6-2.8 69 13.7-41.5 27.5-55.3
iliary condenser is connected to the cold water and the EU-32 1 2.4-3.6 63 20.9-53.1 9.9-42.1
outlet to the outflow. The auxiliary condenser power is a EU-32 2 2.4-3.6 74 20.9-53.1 20.9-53.1
maximum of 30% of the total condenser power. EU-32 3 2.4-3.6 85 20.9-53.1 31.9-64.1
EU-33 1 2.8-4.2 79 23.9-62.5 16.5-55.1
Example EU-33 2 2.8-4.2 90 23.9-62.5 27.5-66.1
EU-33 3 2.8-4.2 102 23.9-62.5 39.2-78.1
The calculation shows that the necessary extract air flow
is 20% greater than the extract air flow to the unit. This Cooling power to the supply air is calculated: Maximum air flow times
does not mean that 20 % of the condenser heat is released 8.4 kW/m2 air.
Cooling power to the chilled beam circuit is calculated: Cooling power
to the water. Because the water condenser is only activat- minus the supply air power.
ed when the heating load is greatest and the maximum
cooling power is used, the operating time is very short
on an annual basis. This means that in practice, the water
consumption is very low.
Fläkt Woods 8733 GB 2009.05 3 Specifications are subject of alteration without further notice.

4. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Control loop diagram and function description
A detailed function description and connections to build-
ing automation is shown in a separate drawing.
Fläkt Woods 8733 GB 2009.05 4 Specifications are subject of alteration without further notice.

5. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Diagram and function description of the water system
Function The valve and valve actuator for the plate heat ex-
changer are not included in the delivery, but are available
The compressors are connected in three cooling stages.
as accessories.
The outgoing water temperature varies depending on
The Combi Cooler governs both the temperature to
whether there is a risk of condensation in the chilled
the main circuit and to the chilled beam circuit. Both of
beams or not.
these setpoints change depending on whether the unit is
in normal operation or setpoint offset (risk of condensa-
Overriding the chilled beam circuit valve tion).
If the heating load on the chilled beam circuit exceeds the
design cooling power, the valve for the outgoing water Normal operation
temperature to the chilled beam circuit will be overrid-
The compressors are controlled by the return temperature
den so that the supply air coil is prioritized. This is to
from the chilled beam circuit. If the system is correctly
ensure that the supply air coil can dehumidify air when
adjusted, the output temperature in the main circuit
required.
should be approximately 14 - 10° C, irrespective of how
many compressors are in operation. In normal operation
Capacity regulation the setpoint of the water to the chilled beam circuit is
The capacity of each circuit is regulated individually. If 15°C as standard.
the pressure on the high-pressure side is too high, that
circuit is closed for 5 minutes. This is to maintain as high Setpoint offset (risk of condensation)
a cooling power as possible and to prevent a shutdown
The compressors are controlled by the water temperature
that would require a manual reset.
downstream of the evaporators. If the system is correctly
adjusted, the output temperature in the main circuit
Water-cooled condenser should be approximately 6–3°C. In setpoint offset opera-
A water-cooled condenser can be ordered as an option. tion the setpoint of the water to the chilled beam circuit is
If the condenser heat cannot be released to the extract 17°C as standard.
air, the condenser temperature will rise. In that case the
water-cooled condenser is automatically engaged at 60°C
to reduce the temperature.
Chilled beam circuit
Buffer tank
Outdoor air
Chilled beam Chilled beam
Supply air
circuit circuit
Combi Cooler delivery boundary
Buffer tank Buffer tank
Z Y A
X B
Outdoor Supply Outdoor Supply
air air air air
+
Combi Cooler delivery boundary Combi Cooler delivery boundary
Control Heating the supply air
The Combi Cooler supplies cooling water to the inte- When the supply air is to be heated, the supplementary
grated supply air coil and to the chilled beam circuit. heat is provided to the coil by the circulation circuit using
Hot water enters the circuit via the integrated plate heat heat exchanger Z.
exchanger. Valve Y regulates the heat exchanger flow to the de-
The valve governing the amount of water to the sup- sired supply air setpoint.
ply air coil and plate heat exchanger is controlled by ex- Three-way valve X is closed during heating.
ternal control equipment. The valve and valve actuator
for the supply air coil are mounted in the Combi Cooler
and are included in the delivery.
Fläkt Woods 8733 GB 2009.05 5 Specifications are subject of alteration without further notice.

6. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Chilled beam network Technical specifications
Three-way valve (A) regulates the temperature in the Unit Power Comp. 1 Comp. 2 Refrigerant, kg
chilled beam network. Pump (B) acts to reduce the in- size model kW A kW A Circ. 1 Circ. 2
crease in pressure when the flow is reduced. Otherwise 21 1 9,2 4,9 14,1 6,9 8,5 5,5
there is a risk of flow noise from the chilled beams’ 21 2 9,2 4,9 21,1 11,5 9,5 5,5
two-way valves when most of the valves are closed. The 21 3 11,9 6,4 24,5 13,2 11 6,5
chilled beam network design temperature is generally 22 1 11,9 6,4 21,1 11,5 12 7
15 - 18° C. 22 2 14,1 6,9 24,5 13,2 13,5 9
In solutions including the Combi Cooler we recom- 22 3 15,7 8,7 30 16,2 15,5 9
mend carrying out cooling requirement and design calcu- 31 1 15,7 8,7 30 16,2 16 9,5
lations for several typical rooms in Fläkt Woods’ product 31 2 21 11,5 36 18,6 17 10
31 3 21 11,5 48 22,8 17,5 10
selection program ExSelAir. The calculation will probably
show that a supply line temperature of 16–17°C will be 32 1 17 10,1 48 22,8 19,5 11
32 2 25 13,2 48 22,8 19,5 11,5
sufficient for the cooling requirement. The benefit of the
32 3 25 13,2 59 31,8 21 11,5
higher temperature is that the risk of condensation form-
33 1 25 13,2 48 22,8 22 12
ing is lower.
33 2 30 16,2 59 31,8 22,5 13
Despite this, the formation of condensation on the 33 3 30 16,2 75 37,2 23 14
chilled beams should be controlled, see below.
Controlling the risk of condensation forming
A condensation sensor is mounted in the main line of
the chilled beam network. The sensor generates an alarm
when the humidity of the indoor air is so high that con-
densation is formed on the surface of the pipe. When con-
densation is detected the water temperature of the chilled
beam network is raised until there is no longer any risk of
condensation forming. Depending on its character one or
more condensation sensors can also be positioned in the
room.
In the event of an alarm from condensation sensors
the BMS (Building Management System) must send in-
formation to the Combi Cooler. The Combi Cooler will
then increase the cooling power to the supply air in order
to compensate for the reduction in the cooling power of
the chilled beams. At the same time the dehumidification
of the supply air increases, drying the indoor air and re-
ducing the risk of condensation forming.
Installation example
− supply air always in the lower unit
− examples with various heat recovery units
Fläkt Woods 8733 GB 2009.05 6 Specifications are subject of alteration without further notice.

7. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Refrigeration diagram Condenser coil Subcooling coil Air
Refrigerant circuit
+ + + +
Water
EXTRACT AIR EXHAUST AIR
A water-cooled condenser can be also be fitted.
Capacity pressure Capacity pressure
switch switch
High pressure High pressure
switch switch
Compressor Compressor
Low pressure Low pressure
switch switch
Evaporator
– Frost protection
sensor
Expansion valve
Flow Temperature sensor, Frost protection
sensor
monitor supply line
–
Evaporator
Expansion valve
Connection diagram
X2
Outgoing summation alarm A + B 51
52
Common
53
Individual setpoint offset
54
Individual SV15 throttled
55
CP2 interlocks the unit 56
57
G
58
In SV – Air cooling/Air heating G0 59
Y
60
24 V AC/DC
G 61
G0 62
GX – Condensation monitor
Q11 63
Q14 64
1 65
GT – KV Chilled beam circuit 2 66
3 67
G 68
SV – Chilled beam valve G0 69
Y 70
C 71
Interlocking FF
N0 72
C 73
GT – Outdoor
N0 74
Fläkt Woods 8733 GB 2009.05 7 Specifications are subject of alteration without further notice.

8. Air handling unit EU TECHNICAL DATA
EUKN Combi Cooler
Dimensions and weight
A
72
D
450
700 400 C
Ødy 32
drain
1300 B
connection
1404
D = 350 for right-hand version (I = 1)
D = 100 for left-hand version (I = 1)
C=1 C=2
C=1
Right
C=2
Left
Extract air
Supply air
Size A B C Weight, kg
21 1548 1554 1104 648
22 1548 1854 1404 741
31 2148 1854 1404 1015
32 2148 2154 1704 1117
33 2148 2454 2004 1258
Fläkt Woods 8733 GB 2009.05 8 Specifications are subject of alteration without further notice.