HHCompact Air Handling Units
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AHU with control
If an AHU with control includes an electric heater, this
must have a separate power supply (400 V ± 10%, 3 ph,
50 Hz). The electric heater supply must be protected by
a correctly sized fuse. The control ensures the correct
control signal and the minimum air flow across the heater.
The electric heater includes:
•
A main disconnect switch
•
Internal fuses (fast acting)
•
Solid-state relays (SSR) that ensure modulating
control. The SSRs used switch via neutral.
The product complies with residential EMC standards
(61000-6-3) with the following restrictions, related to the
flicker effect.
Only one heater
Heating
capacity
Current/
phase
Maximum
impedance Z
Declaration of the connection
condition to comply with
7.5 kW
11 A
0.309
Minimum power supply capability at the
building connection point to the public
network > 100 A per phase
9 kW
13 A
0.257
11 kW
16 A
0.210
15 kW
22 A
0.154
Maximum allowable power supply
network impedance < 0.15 Ohm
18 kW
26 A
0.129
Maximum allowable power supply
network impedance < 0.13 Ohm
19 kW
27A
0.122
Maximum allowable power supply
network impedance < 0.12 Ohm
24 kW
35 A
0.096
Maximum allowable power supply
network impedance < 0.10 Ohm
27 kW
39 A
0.086
Maximum allowable power supply
network impedance < 0.09 Ohm
35 kW
51 A
0.066
Maximum allowable power supply
network impedance < 0.07 Ohm
40 kW
58 A
0.058
Maximum allowable power supply
network impedance < 0.06 Ohm
45 kW
65 A
0.051
Maximum allowable power supply
network impedance < 0.054 Ohm
54 kW
78 A
0.043
Maximum allowable power supply
network impedance < 0.044 Ohm
*
Maximum value at the point of common coupling (PCC) of the
machine and other electrical devices sensitive to the flicker effect.
The values in the table above are calculated based on the
following assumptions
•
A voltage change as defined by the standard
corresponds to a cycle ON – OFF – ON
•
For an interval period of 50 seconds
•
Power supply 400 V
•
Safety margin 15%
4.4.3 - Electric heater in combination with changeover coil
For an AHU with control an electric heater combined
with a changeover coil can be used. The changeover coil
provides primary heating and cooling. The electric heater
is used as a back-up heater in case there is no hot water
available for the changeover coil at a demand for heating.
The electric heater must NOT be used if the changeover
coil is operating and the required entering temperature is
not achieved.
4.5 - Coolers
4.5.1 - Chilled-water coil
•
Always use gloves while carrying out maintenance or
repairs on the cooler element to prevent cuts.
•
Always wear safety glasses while working on the
cooler element.
•
The fins and the pipes can reach temperatures
that can cause burns. During maintenance work
always wear gloves that provide protection against
temperatures up to at least 70°C.
•
It is forbidden to drill holes in the AHU to prevent
damage to pipes and cooler.
•
If the system is compression tested, some water
can remain in the element. The system must comply
with the PED guideline. Compression testing is the
responsibility of the installer. Always de-aerate
the system. If the cabinet is temporarily not in use,
the remaining water must be removed to prevent
freezing.
•
Only use the medium for which the element was
designed. If the medium consists of a mixture of
water/glycol take account of the fact that glycol is a
strong oxidising agent.
•
If only water is used as a medium, the element must
be drained, if the air reaches freezing point.
•
Avoid excessive vibration caused by external devices
and transmitted through the pipes.
•
The unit must be de-energised when the collector
flanges are removed from the pipes.
•
Never exceed the maximum operating pressure.
•
Check the connections on the dimensional drawing.
•
Ensure that the coil has been fully purged.
•
Check connections for leaks.
CAUTION: When the coils are drained, no water must
remain in the circuits to prevent freezing at temperatures
below zero.
•
Check if siphon cover and ball have been correctly
installed.
•
The gauge pressure siphon supplied by Systemair B.V.
is suitable for a gauge pressure of up to 1200 Pa in
the associated section.
•
If a changeover coil is supplied by a heat pump, the
installation must be designed to compensate for the
required heat during the system heat pump defrost
cycle and the heat cannot be drawn from the supply
air. Otherwise the supply air temperature cannot be
achieved. During the heat pump defrost cycle it must
be possible to add enough heat into the system that
the desired entering temperature (heater design
capacity) as well as the required heat for heat pump
defrosting can be guaranteed.
•
Ensure that the AHU is installed high enough to
enable the siphon trap to work correctly.
