Defensor ABS2 Installation and Operating Instructions

1101669 E 0207 

Adiabatic Humidification System 

Defensor ABS2 

Installation and Operating Instructions

Contents 

1. Introduction 4 

1.1 Let’s get started! 4 

1.2 Important instructions! 4 

2. System overview 6 

3. Principle of operation 9 

4. Installation 10 

4.1 Appliance location 10 

4.2 Appliance installation 12 

4.3 Water connections 13 

4.4 Electrical Installation 15 

4.5 Configuration 17 

5. Commissioning, operation and shutdown 19 

5.1 Commissioning/operation 19 

5.2 Shutdown 19 

6. Maintenance 20 

6.1 Important notes on maintenance 20 

6.2 Dismantling procedures 21 

6.3 Cleaning works 23 

6.4 Humidifier reassembly 24 

7. What if … ? 26 

7.1 Malfunction 26 

7.2 Fault elimination 28 

8. Appliance specifications 29 

8.1 Technical data 29 

8.2 Operating conditions 29 

9. Spare parts list 30

1. Introduction 

1.1 Let’s get started! 

1.2 Important instructions! 

4 

Congratulations on your purchase of a Defensor ABS2 adiabatic humidification 

system. 

You now own a powerful humidification system which meets the latest 

hygiene requirements and which offers outstanding operating convenience. 

The special features of the ABS2 are: 

– high humidification capacity 

– sturdy construction 

– modular design 

– low power consumption 

– simple operation and maintenance 

– simple installation without structural modifications 

Please read this installation and operating manual carefully and follow the 

instructions. This will do much to ensure the safe and dependable 

operation of your air humidifier. 

Delivery 

On delivery: 

– Check the appliance for shipping damage. Immediately report any 

damage to the forwarding company and to your Defensor dealer. 

– Check the delivery for completeness. Your Defensor dealer will immediately 

make up any incomplete shipments. 

Safety 

– This unit was shipped from the factory in a perfectly safe condition. To 

ensure its continued safety, please: 

– Follow all instructions and obey all warnings in this installation 

and operating manual. 

– Observe all local safety regulations governing work on mainspowered 

electrical and electronic appliances. 

– The air humidifier should be installed, serviced, maintained and repaired 

only by qualified persons familiar with the equipment. 

– Before carrying out any work on the Defensor ABS2 set the unit out 

of operation, disconnect it from the power supply and secure the 

unit against unintentional power-up according the instructions 

given in chapter 5.2. 

– Setup, maintenance and repair of the electrical installation of the Defensor 

ABS2 must be carried out only by experts being aware of possible 

danger and implications.

– Poorly maintained humidifiers may endanger health. Therefore it is 

mandatory to observe the specified maintenance intervals and to 

carry out maintenance work in strict accordance with the instructions. 

– The humidifier must be operated only under the specified operating 

conditions (see section 8.2, “Operating conditions”). 

– Use only genuine accessories and spare parts available from your 

Defensor supplier. 

– The Defensor ABS2 and the optional accessories must not be modified 

in any way without the written consent of Axair Ltd. 

Installation and operating manual 

– Keep this manual in a safe place where it will be immediately to hand. 

– If you lose the manual, contact your Defensor dealer to obtain an immediate 

replacement. 

Customer service 

Axair Ltd. has an extensive worldwide dealer network with skilled technicians 

offering prompt service at all times. Contact your Defensor dealer in 

the event of any malfunctions or if you have questions concerning air humidification. 

5

2. System overview 

6 

13 

12 

1a Motor housing 

1b Carrier frame 

2a Ring filter (Z92) 

2b Flat filter (Z93) 

3a Aerosol discharge hood and directing hood 

3b Discharge housing 

4a/b Fan, secondary air system 

5a/b Electric motor 

The ABS2 adiabatic humidification system is of modular design. The ABS2 

appliance basically consists of the following main components: 

– Atomizer unit 

– Base unit with integrated controller 

– Filter unit 

The AU35 and AU90 atomizer units 

The atomizer units are available in two different versions: AU35 and 

AU90. 

They can be installed in all base units of the ABS2. Both atomizer units 

operate according to the same basic principle. However, they have 

different humidification capacities (AU35: 3.5 l/hr, AU90: 9.0 l/hr). 

The atomizer units consist of the following items: 

AU90 AU35 

10 

9 

8 

6 

3a 

4 

5 

2a 

1a 

11 

7 

13 

12 

5 4 2b 

10 

6 Impeller, primary air system 

7 Spinning disk 

8 Guide disk 

9 Distributor cone 

10 Suction tube 

11a/b Atomizer grid 

12 Insert 

13 Mains connection 

9 

8 

3b 

1b 

6 7 

11

1 

11 

12 

4 

5 

3a 

6 

The SU11, SU21, DU11 and DU21 base units 

The base units are available in various versions. These are derived from 

two basic configurations: 

– SU11 and DU11: base unit with water-drain connection and automatic 

flushing system. 

– SU21 and DU21: base unit with automatic level security device, but 

without water-drain connection. 

Both basic configurations are available as single units (SU11/SU21) and as 

double units (DU11/DU21). 

The two basic configurations consist of the following items: 

SU11/DU11 SU21/DU21 

(with water-drain) (without water-drain) 

8 

1 Connection for pressurized water 

2 Water reservoir 

3a Inlet valve 

3b Inlet valves (2 pcs.) 

4 Lifting magnet of drain valve 

5 Drain valve 

6 Drain connection 

2 

10 

1 

11 

9 

8 

3b 

12 

6 

7 

7 Drain pipe 

8 Float switch 

9 Maximum level switch 

10 Microswitch for filter unit 

11 Mains connection, atomizer unit 

12 Cable glands 

2 

10 

7

8 

Filter units FU1, FU2 and FU3 

The air inlets of the primary and the secondary air systems are equipped 

with filter units to protect the internals of the humidifier from contamination. 

The following filter units are used: 

– Primary air system 

– FU1 flat filter for use in rooms with very small dust concentrations. 

– FU2 pocket filter for use in rooms with large dust and fibre concentrations. 

FU1 FU2 

– Secondary air system 

– FU3 ring filter for use in rooms with high dust and fibre concentrations 

(for the AU90 atomizer unit only). 

– Flat filter (standard configuration atomizer unit AU35). 

FU3

3. Principle of operation 

1 

The ABS2 adiabatic humidification system operates according to the atomization 

principle. 

The water is drawn in through suction tube (1) from the reservoir and is 

hurled from impeller (2) and spinning disk (3) against atomizer grid (4), 

thereby producing an aerosol (fog). 

Impeller (2) draws in room air through the bottom of the base unit. This air 

then passes through a filter (FU1 or FU2) and forms the primary stream 

which transports the aerosol to the atomizer outlet. 

Fan (6) draws in ambient air through the top surface of the AU35 atomizer 

unit (or through the annular inlet of the AU90) and is also routed to the 

outlet. This secondary air stream takes up the aerosol and discharges it into 

the room. The separate air-guidance systems result in the uniform spatial 

distribution of the aerosol. 

2 

6 

FU1/FU2 

5 

3 

4 

The atomizer unit is powered by a maintenance-free electric motor (5) 

which is controlled by an external humidistat and the built-in controller. 

In both basic configurations of the base units, the water supply to the 

reservoir is controlled by the float switch and the inlet valve (SU11/DU11) 

or the two inlet valves (SU21/DU21), respectively. 

9

4. Installation 

4.1 Appliance location 

10 

The ABS2 appliances are extremely easy to install. Nevertheless all 

installation work should be carried out by suitably trained personnel. 

Locating the humidifier 

Please observe the following locating instructions to ensure the correct 

operation of the humidifier: 

– The ABS2 humidifiers are designed for wall mounting. Make sure that 

the structure (wall, pillar, etc.) on which the appliance is to be mounted 

has sufficient carrying capacity and can accommodate the fastening 

elements. 

– Locate the appliances such that the aerosol stream can spread freely. 

The obstruction of the aerosol stream by objects such as tubular racks, 

machines, supports, etc., will result in stagnation and the formation of 

turbulence which could cause condensation. Since the atomizer units 

can be turned horizontally, the aerosol stream can be directed to bypass 

any obstructions. 

The dimensions (approximate values) for the spreading of the aerosol 

stream of the individual appliance configurations are tabulated below. 

The dimensions relate to a room temperature of 20°C and a relative 

humidity of 45%. The spread of the aerosol stream is reduced at higher 

temperatures and/or lower relative humidity and enlarged at lower 

temperatures and/or higher relative humidity. 

Appliance configuration 

Designation AU35+SU11/21 AU35+DU11/21 AU90+SU11/21 AU90+DU11/21 

Aerosol stream length “l” 5 – 6 m 5 – 6 m 6 – 8 m 6 – 8 m 

Aerosol stream width “b” 1.5 m 3 – 5 m 1.5 m 3 – 5 m 

b 

l 

top view 

Rotation angle “α” 

atomizer unit 

120° 60° 160° 100° 

α 

α 

α 

α 

SU11/21 

b 

α 

l 

α 

DU11/21

– Humid air rises because it is lighter than dry air. Therefore a minimum 

distance must be maintained between the ceiling of the room and the 

appliance. This prevents the aerosol stream from condensing on the 

ceiling. 

Note: If there are support elements (e.g. ceiling joists, roof beams) in the 

vicinity of the aerosol stream, the minimum distance applies to the bottom 

surface of the support element. 


Designation AU35+SU11/21 AU35+DU11/21 AU90+SU11/21 AU90+DU11/21 

Minimum distance “a” between 0.6 m 0.8 m 1.0 m 1.2 m 

ceiling and top of humidifier 

min. 2.2 m a 

side view 

– Mount the appliance such that there is sufficient room for maintenance. 

Also make sure that the appliances are readily accessible and that there 

is no accident risk during maintenance. 

– If appliances are to be installed facing each other, make sure that they 

are at least 15 to 20 m apart. 

– Insulate cold water piping in the vicinity of the aerosol stream (risk of 

condensation). 

– The evaporation process extracts heat from the ambient air. Make sure, 

therefore, that the aerosol stream is not directed at persons. 

– The base unit must be level (longitudinally and transversely) to ensure 

correct operation. 

Locating the external humidistat 

To ensure correct control of the Defensor ABS2 please observe the notes 

on appropriate location of your humidistat (e.g. Defensor H5 humidistat ). 

min. 2.2 m a 

11

4.2 Appliance installation 

12 

22 

344 

205 

280 

81 300 81 

304 

511 

54 

60 

20 

Safety instructions 

– Since the humidifiers are usually mounted at a considerable height, 

please observe the following safety instructions: 

– Whenever possible, use a firm platform when mounting an appliance. 

If a platform cannot be used, use a step ladder (Straight ladders are not 

permissible). 

– Obtain assistance for difficult operations. 

– Use barriers to safeguard the work zone. 

– Use only the fastening material supplied to attach the base unit . If, in 

your particular case, it is not possible to attach the unit with the supplied 

material, choose a fastening system of similar stability. Contact your 

Defensor dealer in cases of doubt. 

Mounting the humidifier 

• Mark the positions for the base-unit fastening holes on the wall (see 

figure below). Use a spirit level to check the alignment. 

283 

474 

32 

ø40 

22 

344 

133 

81 419 419 

81 

304 

205 

280 

511 

54 

60 

283 

32 

ø40 

20 

704 

133

4.3 Water connections 

• Drill the 12 mm diameter holes and insert the supplied screw anchors. 

• Screw in the screws until the heads are 8 mm away from the wall 

surface. 

• Hang the base unit on the screws and then tighten them completely. Use 

the spirit level again to check horizontal alignment. 

• Insert filter unit(s) (FU1 or FU2) from below in the retainers of the base 

unit. Swing the filter unit(s) upwards and fasten with retaining latches. 

Note: Since the filter units are square, their orientation is immaterial. 

• Install the insert from the base unit from above (observe orientation). 

• Carefully insert the atomizer unit into the base unit from above and turn 

it to the desired position. 

Important! Make sure that the electric cable of the atomizing unit is not 

pinched. 

• AU90: Mount the directing hood and then the aerosol discharge hood on 

the atomizer unit. Also mount the ring filter (if used). 

• Plug in the electric cable of the atomizer unit on the left side of the base 

unit. 

Water supply 

Use 6 mm ID/8 mm OD pressure piping for feeding the pressurized water. 

Connect piping to the pressurized-water connection on the base unit (outside 

thread G3/4" or G1/2"). To prevent the inlet valve(s) from soiling, it is 

mandatory to install a sieving filter valve (e.g. option Z261) in the water 

supply. Install the supplied strainer valve in the pressurized-water tubing in 

the vicinity of the appliance. This allows the interruption of the water supply 

without shutting off the main valve. 

Note: The reducing nipple (3/4" to 1/2") for direct connection of the optional 

strainer valve “Z261” to the appliance is included in the delivery 

schedule. 

Admissible water pressure range: 1…6 bar (no pressure peaks) 

Admissible water temperature: 3…35 °C 

Note: Observe the local regulations regarding water connections! 

G 3/4" 

G 1/2" 

Z261 

p= 1…6 bar 

T= 3…35 °C 

13

14 

inner Ø= 40mm 

min. inner Ø= 37mm 

10° 

l 

inner Ø= >40mm 

Water-quality information: 

– Use only fresh drinking water to supply the appliance. It is not permissible 

to supply the appliance with water from open water courses, 

because of the high germ count (microorganisms). 

– We recommend the use of a demineralization system, (e.g. a reverseosmosis 

system) when the water is very hard (mineral-rich). 

Caution! Fully demineralized water (VE water) from a reverseosmosis 

system is aggressive. In this case all lines and connectors of 

the water installation (supply and drain) must be made of stainless steel 

(minimum requirements according to DIN 1.4301) or plastic. 

Note: Base exchangers (water softeners) are not suitable for watertreatment 

purposes because they do not reduce the quantity of minerals 

dissolved in the water. Phosphate cartridges are also unsuitable because 

they increase the minerals dissolved in the water. 

– Do not add disinfectants to the water. These are discharged into the 

ambient air during the atomization process and may cause mucousmembrane 

irritation or allergies. 

Please consult your Defensor dealer if you have questions concerning 

water treatment. 

Water drain line 

Basic units SU11 and DU11 with automatic flushing 

Via a siphon trap, connect the drain of the basic unit (inner Ø= 40mm) 

to a drain line of the building (inner Ø >40mm). Use rigid plastic pipe 

(min. inner Ø= 37mm) for the connection and route the pipe with a 

downward pitch of at least 10°. To ensure that the entire reservoir 

content can be discharged when the appliance is emptied, the connecting 

pipe should not be shorter than: 

– for the SU11 base unit: about 1m – for DU11 base unit: about 2m Use a hose clip on the drain connection to fasten the installed line. 

Notes: 

– It is advisable to use steel piping (min. requirements according to 

DIN 1.4301 if VE-water is used) for the drain line in exposed locations. 

– For safety reasons, do not use flexible tubing for the drain line. 

Base units SU21 and DU21 with automatic level security device 

The drain connections on base units SU21 and DU21 are closed with a 

drain pipe with a threaded cap. The drain cap is not installed when the 

appliance is delivered. To install the drain pipe, proceed as follows: 

• Insert the drain pipe into the drain connection until it comes to a stop, 

then secure it with the hose clip.

4.4 Electrical Installation 

100…115 VAC 

220…240VAC 

F Q 

(max.16 AT) 

L1 

N 

PE 

B1 

J2 

P 

N 

L1 

N 

N 

L1 

P 

N 

X3 

X1 

X2 

100V= 630 mAT 

230V= 315 mAT 

All work concerning the electrical installation must be performed only 

by adequately qualified personnel (electrician or workman with equivalent 

training). 

Please observe all local regulations concerning the electrical installation. 

Wiring diagram ABS2 

A Control PCB (unit 1 up to unit 10, max.) 

B1 Humidistat (internal power supply) 

F External pre-fuse (max. 16 A, slow-blow) 

F1 Atomizer fuse: 220…240V= 6.3 A, slow-blow/250V 

100…115V= 16 A slow-blow/250V 

F2 Primary fuse: 220…240V= 630 mA, slow-blow/250V 

100…115V= 315 mA, slow-blow/250V 

F3 Secondary fuse: 1.6 A, slow-blow/250V 

H1 Red error indicator on base unit 

H2 External error indicator 

J1 Jumper (for SU11/DU11 units) 

J2 Jumper (power supply to humidistat) 

M1 Power supply of humidistat fan (option) 

S1 Float switch 

115 

230 

F2 

SW3 

F1 

F3 

(1.6 AT) 

NPL1 

X2 

L1 

N 

NPL1 

X2 

A 

Unit 2 X1 

N 

Q 

F 

(max.16 AT) 

A 

Unit 3 X1 

100V= 16 AT 

230V= 6.3 AT 

L1 

N 

N 

SW1 

OFF ON 

SW2 

DRAIN 1/2H 1 

FREEZE 1H 2 

FLUSH 2H 3 

RESERVE 4H 4 

1 

2 3 4 

X15 

+ 

+24V 

(max. 50mA) 

Q 

1 

F (max.16 AT) 

Unit 1 

2 3 4 

– + – 

+24V 

M 

H2 M1 

A 

5 6 

X14 X13 

X12 X11 X10 

+24V 

Y1 

+24V 

+24V 

J1 

Y2 

Y3 

S1 

S2 Microswitch of filter unit 

S3 Maximum level switch 

(SU21/DU21 units only) 

SW1 Operating mode selector 

SW2 Flushing interval selector 

SW3 Voltage selector 

Q External mains or service switch 

X1 Power supply terminal 

X2 Terminal for humidistat 

X3 Terminal for atomizer unit 

Y1 Inlet valve 

Y2 Flushing valve (SU11/DU11 units only) 

Y3 2nd inlet valve (SU21/DU21 units only) 

S2 

H1 

S3 

15

16 

The control PCB holding the screw terminals and the DIP switches for 

configuration is located under the cover (fixed with 4 screws), on the left 

side of the base unit. 

Lead all connection cables through the cable glands (strain relief) to 

the control PCB. Important! Thoroughly tighten the cable glands to prevent 

humidity from entering the controller housing. 

Power supply 

Establish the power supply according to the wiring diagram while observing 

the following information: 

– The 2-pole service switch Q (located close to the base unit) and the 

fuse F (max. 10 A, slow-blow) are mandatory. 

– Minimum cable section: 3 x 1.5 mm2 – Caution! The appliances must be connected only to a mains with a 

protective earth. Do not override the protective effect by using an 

extension cable without an earth conductor. 

Any discontinuity in the earth conductor inside or outside the appliance 

or undoing the earth-conductor connection can render the appliance 

dangerous. The deliberate disconnection of the earth conductor is 

prohibited! 

– Caution! Make sure the selected supply voltage (see setting of switch 

“SW3” on control PCB) matches the local mains voltage. If this is not the 

case adjust switch “SW3” accordingly. 

Connection of an external humidistat 

Connect the external humidistat to screw terminal X2 (internal power 

supply) according to the wiring diagram. 

Danger! Mains voltage (up to 230V) is applied to connector L1 of screw 

terminal X2. Therefore, disconnect the unit from the mains (maintenance 

switch to off) before carrying out installation work. 

Note: Particular applications may require the humidistat to be powered 

externally. In this case ask your Defensor dealer for the special wiring 

diagram. 

Connection of an external error indicator 

Connect the external error indicator (24 VDC) to connectors 1 and 2 of 

screw terminal X15 according to the wiring diagram. The maximum 

admissible current is 50 mA. 

Supplying power to the fan of the humidistat Defensor H5-V 

The power supply to the fan of the humidistat Defensor H5-V is made 

via connectors 3 and 4 of screw terminal X15 (see wiring diagram). 

To conclude setup work connect the grounding wire to the cover, then fix 

the cover with the 4 Phillips screws.

4.5 Configuration 

Configuration of the ABS2 is done via switches SW1 (operating mode 

selector), SW2 (flushing interval selector) and SW3 (voltage selector) of 

the control PCB. 

Danger, lethal voltage! Before starting configuration work, set the 

Defensor ABS2 out of operation and disconnect the unit from the 

mains according to chapter 5.2. 

Loosen the 4 screws of the cover on the left side of the base unit. Carefully 

lift off the cover, then remove the grounding wire from the cover. 

Setting the operating mode (SW1) 

Switch OFF ON 

1 

(Drain) 

2 

(Freeze) 

3 

(Flush) 

SW3 

Setting for appliances including base unit 

without drain valve (SU21 and DU21). 

Antifreeze disabled. 

SW1 

Note: This switch has no function on base units SU21/DU21! 

Periodic flushing during humidification disabled. 

Note: This switch has no function on base units SU21/DU21! 

4 reserved 

off on 

1 

2 

3 

4 

SW2 

Setting for appliances including base unit with 

drain valve (SU11 and DU11). 

Antifreeze enabled, required when operating 

the ABS2 at temperatures around the freezing 

point (e.g. in cold-storage depots). 

Periodic flushing during humidification enabled. 

17

18 

Setting the flushing interval (SW2) (SU11/DU11 only) 

The flushing interval is the period between two flushing cycles. A timer built 

into the controller logs the time (based on the hours of operation of the 

atomizer). A flushing cycle is initiated each time the specified interval has 

elapsed. 

The time between two flushing cycles can be defined as 30, 60, 120 or 240 

minutes. The time to be set depends on the prevailing operating conditions 

(dustiness, water quality). 

Recommendation: – Very dusty conditions and/or hard water: 

Flushing interval 30 minutes 

– Normal dustiness and/or medium-hardness water: 

Flushing interval 60 - 120 minutes 

– Slight dustiness and/or demineralized water: 

Flushing interval 120 - 240 minutes 

Setting of switch SW2 Flushing interval in minutes 

1 30 

2 60 

3 120 

4 240 

Selection of the supply voltage (SW3) 

The ABS2 supports two different voltage ranges. Selection of the appropriate 

supply voltage is done via switch SW3. 

Setting of switch SW3 Supply voltage 

115 100…115 VAC/50…60 Hz 

230 220…240 VAC/50…60 Hz 

To conclude setup work connect the grounding wire to the cover, then fix 

the cover with the 4 Phillips screws.

5. Commissioning, operation and shutdown 

5.1 Commissioning/operation 

5.2 Shutdown 

Proceed as follows to ready the humidifier for operation: 

It is assumed that the unit has already been installed, connected and 

configured according to the instructions (see chapter 4). 

• Turn on the water supply. 

Attention! Appliances with base unit SU21 or DU21; check whether the 

drain neck is closed properly. 

• On the external humidistat set the reference humidity to the desired 

value. 

• Actuate the maintenance switch. 

Appliances with base unit SU11 or DU11: the water reservoir is flushed 

and then filled up to the working level. 

Appliances with base unit SU21 or DU21: the water reservoir is filled up 

to the working level. 

The humidifier is now in the ready mode. The atomizer will be activated only 

if the air humidity is lower than the set reference value. On base units SU11/ 

DU11 the flushing of the water reservoir always takes place according to 

the preset flushing interval, even in standby mode (see section “Setting the 

flushing interval” in chapter 4.5). 

If malfunction occurs during operation, the red error indicator on the 

front panel of the base unit starts flashing or lights up constantly (for 

additional information refer to chapter 7). 

Proceed as follows to put the humidifier out of operation: 

• Disconnect the humidifier from the mains (set the maintenance 

switch to off) and secure the system against unintentional start-up. 

Danger, lethal voltage! If the humidistat controlling your unit is fed 

by an external power supply, the external voltage is applied to 

the control PCB. In this case you must disconnect the humidistat 

from power supply. 

The water reservoir of appliances equipped with base unit SU11 or 

DU11 is drained and flushed automatically at shutdown time. 

The water reservoir of appliances with base unit SU21 or DU21 should 

be drained manually via the drain neck if the humidifier is to be set out 

of operation for an extended period (hygiene). 

• Turn off water supply (close sieving filter valve). 

19

6. Maintenance 

6.1 Important notes on maintenance 

20 

Dust pollution level Periodic 

cleaning 

high, e.g. 

textile mills, print shops 

and paper industry, 

wood processing 

medium, e.g. 

storage facilities of 

the food industry 

low, e.g. 

cold rooms

Water Hardness Maintenance 

quality level intervals 

hard >18° d 2 - 4 weeks 

normal 8 - 18° d 4 - 8 weeks 

soft (VE) 0 - 8° d 8 weeks 

6.2 Dismantling procedures 

– Complete maintenance of the humidifier 

Depending on the appliance configuration, a complete maintenance 

intervention takes from 3/4 h (single unit) to 1 1/4 h (double unit). 

Maintenance frequency depends on the operating conditions (see 

opposite table). In addition to the parts listed in section “Periodic 

cleaning”, the following items require thorough cleaning: 

– Discharge assembly, discharge hood/housing 

Note: Dismantling procedures and cleaning of individual components required 

on the occasion of periodic servicing or overall maintenance are described 

in chapters 6.2 and 6.3. 

Safety precautions 

– Danger, lethal voltage! Before you start cleaning, set the Defensor 

ABS2 out of operation and disconnect the unit from the mains 

according to chapter 5.2. 

– Make sure that those around you know that you are working on the 

appliance. 

– Since the humidifiers are usually mounted at a considerable height, 

please observe the following safety instructions: Whenever possible, 

use a firm platform when maintaining an appliance. If a platform cannot 

be used, use a step ladder (Straight ladders are not permissible). 

Putting the system out of operation 

Put the humidifier out of operation according to chapter 5.2. 

Filter unit removal (FU1/FU2) 

• Turn the retainer latch of the filter unit on the bottom of the base unit to 

the side. Remove the filter unit (base units SU11/SU21) or the two filter 

units (base units DU11/DU21) in a downward direction. 

Note: Protect the inside face of the filter against contamination by laying 

the filter unit with the inside surface facing downwards. 

Water reservoir removal 

• DU11/DU21: Turn the retaining latches of the connecting bar to the side. 

Remove the connecting bar. 

• SU21/DU21: Undo the flexible tubing clip on the drain tubing. 

• Pull the drain tubing on the water reservoir downwards and remove 

sideways from the connection on the water reservoir. 

• Turn the retaining latches of the water reservoir to the side and pull the 

water reservoir out from below. 

21

22 

12 

11a 

Atomizer unit removal 

• Unplug the electric cable(s) between the atomizer unit(s) and the base 

unit. 

• AU90: Lift off the aerosol discharge hood and then the directing hood 

(11a). Remove the ring filter unit (12, if installed). 

AU35: Undo the two catches and lift off the discharge housing together 

with the flat filter (11b). 

• Carefully lift the atomizer unit (10) on the carrier frame (1a/1b) up and 

out of the base unit. 

• Place the atomizer unit (10) together with the fan wheel downwards onto 

the carrier frame. Make sure that the unit does not stand on the fan 

wheel (use wooden blocks). 

• Hold the disks (9) (guide disk (2), distributor cone (3), 3 spinning disks 

(4) and impeller (5)) firmly and undo the suction tube (6) in an anticlockwise 

direction. 

• Remove the disks (9) from the drive shaft. Press the impeller and spinning 

disks away from the distributor cone by hand. Then, remove the 

distributor cone from the guide disk. 

• Pull the catch springs outwards and carefully withdraw the atomizer 

grid (7) from the centring device. 

• Remove the insert (8) from the base unit. 

1a 

2 

3 

4 

5 

6 

7 

8 

9 

10 

1b 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11b

6.3 Cleaning works 

Cleaning the water system 

Wash the water reservoir, insert, atomizer grid, suction tube, and the disks 

using a lukewarm soap solution and then rinse them thoroughly with water. 

If the components are heavily encrusted with chalk, soak them in 8 % formic 

acid until the lime layer is dissolved. Finally, treat the components as 

described above. 

During the cleaning operation make sure that: 

– the external edges of the disks are not damaged. Disks damage 

reduces the efficiency of the humidifier and can cause bearing damage 

(unbalance). 

– the vanes of the atomizer grid are not bent. Bent vanes adversely affect 

the atomization process. 

– the drain opening of the insert is open so that the return water can flow 

back into the water reservoir. 

– the inlet of the water suction connection is open so that the water 

throughput is ensured. 

Use a cloth moistened with soap solution or a sponge to wash the components 

inside the base unit and the remaining components of the atomizing 

unit. Then rub the components with a wet cloth (clean water) several times. 

If the components are heavily encrusted with chalk, rub them with an acidsoaked 

cloth (8 % formic acid). Allow the acid to act for some time and then 

wash the components. 

Caution! Make sure that no cleaning agents (water, soap solution, acid, 

etc.) get into the electric motor during cleaning. 

The strainer valve (13) must be inspected during every service intervention 

and cleaned if necessary. 

Cleaning-agent notes: 

– Formic acid is available at all pharmacies. 

Caution! Formic acid attacks the skin as well as the mucous membranes. 

Therefore protect your skin, the eyes and the respiratory tract 

from contact with the acid or its fumes. (Wear gloves, safety goggles and 

work in a well-ventilated room or outdoors). 

– The use of disinfectants is allowed only when they leave no toxic 

residues. In any case the components must be thoroughly rinsed with 

water after cleaning. 

– Caution! Do not use solvents or other aggressive substances for 

cleaning. 

– Do not use scouring equipment (wire brushes, scouring cloths, etc.) 

for cleaning. Scratches in the surfaces of the components encourage 

the growth of microorganisms. 

23

6.4 Humidifier reassembly 

24 

Cleaning the air system 

Filter units 

– If the filter units are only lightly contaminated: clean the outside 

surface of the filter units with a vacuum cleaner. 

– If the filter units are heavily contaminated: replace them. 

Important notes: 

– Apply the vacuum cleaner only to the outside surface of the filter units 

so that the contaminatory matter does not penetrate deeper into the 

filter fabric and reduce the efficiency of the filter. 

– The filter units must not be used for more than 1 year. Under severe 

operating conditions, the maximum service time must be reduced 

accordingly. 

– Install only absolutely dry filters. Damp filters promote the growth of 

microorganisms. 

Discharge housing / aerosol discharge hood and directing hood 

Wash all components with a lukewarm soap solution and then rinse 

thoroughly with water. 

Note: observe the instructions regarding cleaning agents in the “Cleaning 

the water system” section. 

Before starting with the reassembly, check all components for operational 

integrity and any defects. Pay special attention to the float switches and the 

drain valve (SU11 and DU11 only). Replace defective components. 

Reservoir installation 

• Insert the reservoir on the drain connection side into the retainer of the 

base unit, swing upwards and secure with the retaining latches. 

• Push the drain tubing onto the connection on the reservoir. 

• Caution! In the case of the SU21/DU21 base units, secure the drain 

tubing with a hose clip and close the drain tube with the threaded 

cap. 

Filter unit installation 

• Insert filter unit(s) (FU1 or FU2) from underneath into the retainers of the 

base unit. Swing up and secure with the retaining latches. 

Note: The filter units are square and their orientation is immaterial.

Atomizer unit installation 

• Carefully push the atomizer grid onto the centring device until the 

latching springs engage. 

• Mount the disk unit: slip the distributor cone onto the guide disk, then 

mount the spinning disks and the impeller to the distributor cone. 

• Grease the drive shaft and thread (use silicone or water-pump grease). 

Now mount the disk unit on the drive shaft (Note! Observe position of 

drive studs). 

• Hold the disks firmly and screw the suction tube clockwise on the drive 

shaft and tighten by hand. 

• Install the insert in the base unit from above. 

• Carefully guide the atomizer unit into the base unit from above and turn 

it into the desired position. 

Caution! Make sure that the electric cable of the atomizer unit does not 

become pinched. 

• AU35: Mount the discharge housing together with the flat filter on the 

atomizer unit, and secure to the carrier frame with the two snap catches. 

AU90: Mount the directing hood on the atomizer unit followed by the 

aerosol discharge hood. Mount the ring filter unit (if installed). 

• Plug the electric cable(s) of the atomizer unit(s) into the connector(s) on 

the left side of the base unit. 

Starting 

Start the appliance as described in section 5.2. 

25

7. What if … ? 

7.1 Malfunction 

26 

The following table presents a selection of faults that may occur during 

operation of the humidifier, together with notes on their cause and appropriate 

remedies. 

Malfunction Cause Remedy 

The atomizer does not work 

and the red fault indicator 

flashes. 

The atomizer does not work 

and the red fault indicator 

lights up permanently. 

A puddle of water forms on the 

base unit after switching on. 

Microswitch of the filter unit has 

been triggered: 

– Filter unit(s) FU1 or FU2 are 

either missing or located 

incorrectly. 

– Microswitch defective. 

Level in the water reservoir too 

high or water reservoir is empty: 

– Water supply turned off or 

blocked. 

– Water inlet valve not electrically 

connected or defective. 

– SU11/DU11: Drain valve not 

tight, not electrically connected 

or defective. 

– Float switch jammed or heavily 

encrusted with chalk. 

Level in the water reservoir too 

high, maximum level switch 

triggered: 

– Float switch jammed or encrusted 

with chalk. 

– SU11/DU11: jumper J1 not 

installed (see provided wiring 

diagram). 

– Violent water movements in the 

reservoir due to air in the 

supply line. 

The electric cable is pinched under 

the atomizer unit. 

The atomizer does not run. Maintenance switch is set to “Off”. 

Primary fuse F2 or secondary fuse 

F3 on control PCB of the base unit 

defective. 

– Mount the filter unit(s) appropriately. 

– Check microswitch, replace, as 

required. 

– Check water supply line and 

the strainer valve. 

– Check the water inlet valve. 

Replace if necessary. 

– Check drain valve. Clean or 

replace if necessary. 

– Check float switch. Clean or replace 

if necessary. 

– Check float switch. Clean or replace 

if necessary. 

– Install jumper J1 (see wiring 

diagram). 

– Note: This can occur only during 

initial operation or after draining 

the water line. 

Note: after having eliminated the 

problem, disconnect the unit from 

the mains for at least 10 seconds 

to reset the fault indicator. 

Remove the pinched cable. 

Set maintenance switch to “On”. 

Replace primary fuse F2 or secondary 

fuse F3 (according to the description 

given in chapter 7.2).

Malfunction Cause Remedy 

The atomizer keeps running 

and cannot be switched off by 

reducing the reference humidity 

value. 

The humidistat does not switch. 

The atomizer does not run. 

The humidistat activates the atomizer, 

but the atomizer does 

not start. 

The set reference humidity value 

is not reached. The atomizer runs 

continuously. 

The atomizer runs noisily (motor 

noise audible). 

Air humidity very low (95 % rh). 

Humidistat defective. 

Humidistat incorrectly set. 

Atomizer fuse F1 in base-unit terminal 

box is defective. 

The mains connection to the particular 

humidifier is interrupted. 

The electric cable of the atomizer 

unit is not connected. 

The thermostatic switch of the electric 

motor has tripped (motor is overheated). 

Air filters heavily contaminated. 

Room too large. 

Suction tube of atomizer unit 

blocked. 

Suction tube not installed. 

Disks not correctly installed. 

Suction tube has become undone. 

None. 

Check humidistat. Replace if necessary. 

None. 

Check humidistat. Replace if necessary. 

Set humidistat to the correct reference 

humidity value. 

Replace atomizer fuse F1. 

Check the wiring. 

Plug the atomizer-unit cable into 

the base unit 

Check the atomizing head (The 

motor shaft must rotate freely). 

Clean if necessary. Contact Defensor 

dealer if necessary 

Clean air filters. 

Contact Defensor dealer. 

Check suction tube. Clean if necessary. 

Install suction tube. 

Check disks. Mount them correctly. 

Tighten suction tube. 

27

7.2 Fault elimination 

28 

Notes regarding fault elimination 

– Before eliminating faults, the Defensor ABS2 must be taken out of 

operation according chapter 5.2. 

Danger! Make sure the mains supply to the humidifier is disconnected 

(check with voltage tester) and the stop cock of the water supply is 

closed. 

– Have faults eliminated by adequately qualified and trained personnel 

only (e.g. by a service engineer of your Defensor supplier). 

Malfunctions caused by the electrical installation must be repaired by 

authorized personnel only. 

Replacement of the fuses 

Caution! The electronic components on the control PCB are very susceptible 

to electrostatic discharge. When carrying out repairs to the control unit, 

appropriate measures (ESD-protection) must be taken to prevent damage 

to electronic components. 

Danger, lethal voltage! Before replacing defective fuses, set the 

Defensor ABS2 out of operation and disconnect the unit from the 

mains according to chapter 5.2. 

• Loosen the 4 screws of the cover on the left side of the base unit. 

Carefully lift off the cover, then remove the grounding wire from the 

cover. 

F2 

F1 

F3 

• Replace fuses F1, F2 and F3 of the control PCB only with fuses 

matching the specifications below: 

– Atomizer fuse F1: 

Supply voltage 220…240V: 6.3 A, slow-blow/nom. voltage 250V 

Supply voltage 100…115V: 16 A, slow-blow/nom. voltage 250V 

– Primary fuse F2: 

Supply voltage 220…240V: 315 mA, slow-blow/nom. voltage 250V 

Supply voltage 100…115V: 630 mA, slow-blow/nom. voltage 250V 

– Secondary fuse F3: 1.6 A, slow-blow/nom. voltage 250V 

Caution! Never use refurbished fuses. Do not bridge the fuse holder. 

• Following replacement of the fuse(s) connect the grounding wire to the 

cover, then fasten the cover with the 4 Phillips screws.

8. Appliance specifications 

8.1 Technical data 


Designation AU35+SU11/21 AU90+SU11/21 AU35+DU11/21 AU90+DU11/21 

Humidification capacity 3.5 l/h 9 l/h 7 l/h 18 l/h 

Air circulation 300 m3 /h 800 m3 /h 600 m3 /h 1600 m3 /h 

Power consumption 200 W 290 W 400 W 580 W 

Supply voltage 100…115VAC/50…60Hz or 220…240VAC / 50…60Hz 

Atomizer fuse F1 100…115V= 16A, slow-blow/250V or 220…240V= 6.3A, slow-blow/250V 

Primary fuse F2 100…115V= 630mA, slow-blow/250V or 220…240V= 315mA, slow-blow/250V 

Secondary fuse F3 1.6 A, slow-blow/250V 

Dimensions in mm (W x H x D) 462 x 474 x 511 462 x 704 x 511 1000 x 474 x 511 1000 x 704 x 511 

Weight (dry) 25.4 kg 27.5 kg 45.8 kg 50 kg 

Water content 

Water consumption 

1 l 1 l 2 l 2 l 

– without drain max. 3.5 l/hr max. 9.0 l/hr max. 7.0 l/hr max. 18.0 l/hr 

– Flushing cycle 30 min. max. 7.5 l/h max. 13.0 l/h max. 15.0 l/hr max. 26.0 l/hr 

– Flushing cycle 60 min. max. 5.5 l/hr max. 11.0 l/hr max. 11.0 l/hr max. 22.0 l/hr 



Feed-water pressure 100 - 600 kPa (1.0 - 6.0 bar) 

Pressurized water connection 8 mm OD/6 mm ID tubing, connection 3/4" or 1/2" (outside thread) 

Water drain connection Inner Ø 40 mm 

Drive Maintenance-free electric motor with thermostatic switch 

Control External humidistat (e.g. Defensor H5) 

Test and conformity certificates SEV, CE 

8.2 Operating conditions 

Temperature range: 2 - 40 °C 

Note: Contact your Defensor dealer if lower temperatures 

are involved. 

Humidity range: 0 - 98 % rh 

Water quality: Tap water 

Water demineralization is recommended if the mineral 

salt content of the water is high (>15 dH°, >27 fH°). 

Air: If the air is very dirty, it is advisable to use the pocketfilter 

unit FU2 in the primary air system and the ringfilter 

FU3 (AU90 only) in the secondary air system. 

Note: See section 4.1 “Appliance location” for additional information. 

29

9. Spare parts list 

30 

106 

107 

AU90 

104 

101 

102 

103 

105

Item Part no. Part designation 

101 1102094 Spare filter for FU3 

102 1104088 Fan 

103 1103920 Capacitor for supply voltage 220…240V 

1103924 Capacitor for supply voltage 100…115V 

104 1104143 Motor 220V/60Hz 

1104145 Motor 220…240V/50Hz 

1104149 Motor 100…115V/60Hz 

1104154 Motor 100…115V/50Hz 

105 1104085 Atomizer grid 

106 1104138 Turbine cpl. 

107 1110550 Insert 

31

32 

201 

206 

207 

203 

AU35 

202 

204 

205


201 1102369 Spare filter AU35 

202 1103941 Fan 

203 1103913 Capacitor for all supply voltages (2 pcs. for supply voltage 100…115V) 

204 1104348 Motor 220…240V/50Hz 

1109190 Motor 220V/60Hz 

1104353 Motor 100…115V/60Hz 

1104356 Motor 100…115V/50Hz 

205 1104517 Atomizer grid 

206 1104138 Turbine cpl. 

207 1110550 Insert 

33

34 

308 

307 

309 

301 

303 

306 

305 

SU11 

311 

310 312 

314 

302 

304 

313




303 1103934 Water reservoir 

304 1103927 Set of plugs 

305 1104103 Inlet valve 

306 1104107 Microswitch of filter unit 

307 1104112 Error indicator red 

308 1104122 Set of fuses (220…240VAC) 

1104127 Set of fuses (100…115VAC) 

309 1112403 Control PCB 

310 1104119 Sealing plates 

311 1104116 Socket complete 

312 1104091 Lifting magnet 

313 1104099 Float switch 

314 1104095 Drain connection 

35

36 

408 

407 

409 

401 

410 

406 

403 

411 

405 

415 

SU21 

402 

414 

412 

413













412 1104129 Maximum level switch 



415 1104485 Drain pipe 

37

38 

508 

507 

501 

509 

514 

506 

504 

DU11 

511 

510 512 

502 

503 

505 

513





504 1103927 Set of plugs 









512 1104091 Lifting magnet 



39

40 

608 

615 

607 

601 

609 

614 

610 

606 

611 

DU21 

603 

602 

605 

612 

613













612 1104129 Maximum level switch 



615 1104485 Drain pipe 

41

Notes

© Axair Ltd. 1998, Printed in Switzerland 

Technical data subject to modification

Reg.No. 40002-2 

Manufacturer: 

Axair Ltd. Systems for Air Treatment 

A WMH Walter Meier Holding Company 

CH-8808 Pfäffikon (Switzerland), Talstr. 35-37, P.O. Box 

Telephone +41 55 416 61 11, Fax +41 55 416 62 62 

Internet http://www.axair.ch, E-Mail info@axair.ch 

Consulting, Sales and Service:

Defensor ABS2 Installation and Operating Instructions

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