STIEBEL ELTRON PER Operation Instruction

OPERATION AND INSTALLATION

OBSLUHA A INSTALACE

OBSŁUGA I INSTALACJA

ОБСЛУЖВАНЕ И ИНСТАЛИРАНЕ

ЭКСПЛУАТАЦИЯ И УСТАНОВКА

Fully electronically controlled comfort instantaneous water heater with Mini FFB wireless remote

control | Plně elektronicky regulovaný komfortní průtokový ohřívač s tlačítkem bezdrátového ovládání

Mini-FFB| Całkowicie elektronicznie regulowany komfortowy przepływowy ogrzewacz wody ze

zdalnym sterowaniem Mini-FFB | Изцяло електронно регулиран комфортен проточен бойлер

с безжичен превключвател Mini-FFB | Проточный нагреватель повышенной комфортности с

электронной системой полного регулирования и пультом дистанционного управления Mini-FFB

» PER 18/21/24

1

ECO

2

Made in Germany

2 | PER 18/21/24 www.stiebel-eltron.com

CONTENTS | SPECIAL INFORMATION

SPECIAL INFORMATION

- The appliance may be used by children aged3

and older and persons with reduced physical,

sensory or mental capabilities or a lack of expe-

rience and know-how, provided that they are su-

pervised or they have been instructed on how to

use the appliance safely and have understood the

potential risks. Children must never play with the

appliance. Children must never clean the applian-

ce or perform user maintenance unless they are

supervised.

- The tap can reach temperatures of up to 60°C.

There is a risk of scalding at outlet temperatures

in excess of 43°C.

- The appliance is suitable for supplying a shower

(shower operation). If the appliance is also or

exclusively used for shower operation, the qu-

aliﬁed contractor must limit the temperature

setting range using the temperature limit (55°C

or lower) in the appliance. When using preheated

water, it must be ensured that the inlet tempera-

ture does not exceed 55°C.

- Ensure the appliance can be separated from the

power supply by an isolator that disconnects all

poles with at least 3mm contact separation.

- The speciﬁed voltage must match the power

supply.

- The appliance must be connected to the earth

conductor.

- The appliance must be permanently connected to

ﬁxed wiring.

- Secure the appliance as described in chapter "In-

stallation/ Installation".

- Observe the maximum permissible pressure (see

chapter "Installation/ Speciﬁcation/ Data table").

- The speciﬁc water resistivity of the mains water

supply must not be undershot (see chapter "Insta-

llation/ Speciﬁcation/ Data table").

- Drain the appliance as described in chapter "In-

stallation/ Maintenance/ Draining the appliance".

SPECIAL INFORMATION

OPERATION

1. General information ��3

1.1 Safety instructions �� 3

1.2 Other symbols in this documentation �� 3

1.3 Units of measurement �� 3

2. Safety �� 3

2.1 Intended use �� 3

2.2 General safety instructions �� 4

3. Appliance description ��4

4. Settings ��5

4.1 Settings and displays on the appliance �� 5

4.2 Settings in the INFO menu �� 6

4.3 Settings on the wireless remote control �� 8

4.4 Further functions ��8

4.5 Recommended settings �� 8

5. Cleaning, care and maintenance ��8

6. Troubleshooting ��8

INSTALLATION

7. Safety �� 9

7.1 General safety instructions �� 9

7.2 Shower operation�� 9

7.3 Instructions, standards and regulations �� 9

8. Appliance description �� 10

8.1 Standard delivery �� 10

9. Preparation �� 10

9.1 Installation location �� 10

9.2 Water installation �� 10

10. Installation �� 11

10.1 Standard installation �� 11

10.2 Alternative installation methods��13

10.3 Completing the installation ��15

10.4 Installation of wireless remote control �� 15

11. Commissioning �� 15

11.1 Initial start-up �� 15

11.2 Recommissioning ��15

12. Appliance shutdown �� 15

13. Troubleshooting �� 16

13.1 Customer service mode �� 16

14. Maintenance �� 17

15. Speciﬁcation �� 17

15.1 Dimensions and connections �� 17

15.2 Wiring diagrams �� 18

15.3 Factory settings ��18

15.4 DHW output �� 18

15.5 Application areas/ Conversion table �� 18

15.6 Pressure drop �� 18

15.7 Fault conditions ��18

15.8 Test symbols �� 19

15.9 Energy consumption data �� 19

15.10 Data tables �� 19

GUARANTEE

ENVIRONMENT AND RECYCLING

OPERATION

General information

ENGLISH

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OPERATION

1. General information

The chapters "Special information" and "Operation" are intended

for both users and qualiﬁed contractors.

The chapter "Installation" is intended for qualiﬁed contractors.

Note

Read these instructions carefully before using the appli-

ance and retain them for future reference.

Pass on the instructions to a new user if required.

1.1 Safety instructions

1.1.1 Structure of safety instructions

!

KEYWORD Type of risk

Here, possible consequences are listed that may result

from failure to observe the safety instructions.

 Steps to prevent the risk are listed.

1.1.2 Symbols, type of risk

Symbol Type of risk

Injury

Electrocution

Burns

(burns, scalding)

1.1.3 Keywords

KEYWORD Meaning

DANGER Failure to observe this information will result in serious

injury or death.

WARNING Failure to observe this information may result in serious

injury or death.

CAUTION Failure to observe this information may result in non-se-

rious or minor injury.

1.2 Other symbols in this documentation

Note

General information is identiﬁed by the adjacent symbol.

 Read these texts carefully.

Symbol Meaning

Material losses

(appliance damage, consequential losses and environmen-

tal pollution)

Appliance disposal

 This symbol indicates that you have to do something. The ac-

tion you need to take is described step by step.

1.3 Units of measurement

Note

All measurements are given in mm unless stated otherwi-

se.

2. Safety

2.1 Intended use

The appliance is intended for domestic use. It can be used safely

by untrained persons. The appliance can also be used in non-

-domestic environments, e.g.in small businesses, as long as it is

used in the same way.

This pressurised appliance is suitable for heating domestic hot

water or for reheating preheated water. The appliance can supply

one or more draw-off points.

Any other use beyond that described shall be deemed inappropria-

te. Observation of these instructions and of the instructions for any

accessories used is also part of the correct use of this appliance.

!

OPERATION

Appliance description

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2.2 General safety instructions

Note

The remote temperature control has a lithium button cell

as a battery for the power supply.

Remove spent batteries. Leaking batteries cause dam-

age which is excluded from any warranty. Do not charge

non-rechargeable batteries.

Never use rechargeable batteries.

If the appliance is not used for a prolonged period, remo-

ve the battery (see chapter "Troubleshooting/ Replacing

the battery in the remote temperature control").

CAUTION Burns

The tap can reach temperatures of up to 60°C. There is a

risk of scalding at outlet temperatures in excess of 43°C.

CAUTION Burns

If operating with preheated water, e.g. from a solar ther-

mal system, the DHW temperature may vary from the

selected set temperature.

Where children or persons with limited physical, sensory or men-

tal abilities are allowed to use this appliance, we recommend a

permanent temperature limit. A qualiﬁed contractor can set the

limit for you.

!

Material losses

The user should protect the appliance and its tap against

frost.

3. Appliance description

The appliance heats water as it ﬂows through it. The DHW outlet

temperature can be variably adjusted at the temperature selector.

From a certain ﬂow rate, the control unit regulates the correct hea-

ting output, subject to the temperature selected and the current

cold water temperature.

The ﬂow rate is automatically reduced by the ﬂow regulator valve

when inlet temperatures are low and the required outlet tempera-

ture is high. This ensures that the required temperature is reliably

achieved. If operating the appliance with preheated water, "Error"

will appear on the display at temperatures of 45°C and above.

Two different temperatures can be saved and called up quickly.

The ECO function limits the ﬂow rate to the ECO ﬂow rate and sets

a pre-deﬁned ECO temperature. The appliance also has child-

prooﬁng functions, a Wellness program, automatic water volume

control, dynamic anti-scalding protection and a permanent tempe-

rature limiting feature. The background lighting on the appliance's

display can also be used as an orientation light.

Heating system

The bare wire heating system has a pressure-tested plastic ca-

sing. The heating system is suitable for hard and soft water areas

and is largely insusceptible to scale build-up. This heating system

ensures rapid and efﬁcient DHW availability.

Note

The appliance is equipped with an air detector that lar-

gely prevents damage to the heating system. If, during

operation, air is drawn into the appliance, the appliance

shuts down for one minute, thereby protecting the hea-

ting system.

OPERATION

Settings

ENGLISH

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4. Settings

4.1 Settings and displays on the appliance

26�02�02�0929

Temperature display

Bar graph showing output

Second display

e.g. time

Memory buttons 1 and 2

Info and ECO button

ECO display

Temperature selector

Display field for additional information:

Service, error

Backlighting

Display field:

Wellness, automatic water volume control,

childproofing, ECO, second display, clock

Display ﬁeld

Wellness Second line

Automatic water volume

control

Time

ECO mode Orientation light

Childproofing

Display ﬁeld for additional information

 Please contact your qualiﬁed contractor if the following sym-

bols are displayed:

Error

Service

4.1.1 Setting the temperature

The desired temperature can be variably adjusted by turning the

rotary selector. The set temperature is displayed.

Operation Display

Select a temperature

between 30 and 60°C via

stepless setting

e.g. 43°C

OFF = heating switched

off

4.1.2 Memory buttons

Using the memory buttons, you can quickly call up two preferred

temperatures. These temperatures can be selected by you.

Allocating memory buttons

Select the temperature

between 30 and 60°C that

you wish to save

e.g. 38°C.

Press button1 or button2 for

3seconds

e.g. 38°C and 43°C

Display flashes once brie-

fly, temperature is stored

Calling up memory buttons

Press button1 or button2 e.g. 38°C and 43°C

4.1.3 Selecting/deselecting ECO

The ECO function is activated and deactivated with the ECO button.

If you have activated the ECO function, a green LED below the

button lights up. The ECO symbol is also displayed.

The ECO function limits the ﬂow rate to the ECO ﬂow rate and sets

a pre-deﬁned ECO temperature. Both values can be adjusted via

the INFO menu.

Note

The ECO function is deactivated each time you adjust the

temperature on the appliance (with the temperature se-

lector or via the memory buttons). You must then re-ac-

tivate the ECO function if required.

If you have selected the temperature via the wireless remote con-

trol, the ECO function is re-activated automatically after water has

been drawn off.

Press the ECO button:

Selecting ECO

Green LED illumi-

nates.

Press the ECO button:

Deselecting ECO

LED is not lit.

OPERATION

Settings

6 | PER 18/21/24 www.stiebel-eltron.com

4.2 Settings in the INFO menu

Use the ECO button to access the INFO menu, where you can set

comfort functions to individual preferences and/or call up values:

ECO temperature/ﬂow rate adjustment, childprooﬁng, Wellness

program, automatic water volume control. The ECO button can

also be used to set the brightness of the display and the orien-

tation light.

You can access the setting options by pressing the ECO button for

longer than three seconds.

Then press the ECO button again repeatedly to access each fun-

ction.

When you have reached the required function, you can change

the settings for that function by turning the temperature selector.

Operation Display

Accessing the menu

Press the ECO button for

3seconds

38°C

All settings in the INFO menu are saved immediately.

Exiting the menu

Press the ECO button for

3seconds.

Selected settings

If no button is pressed for approx.40seconds, the INFO menu is

exited.

4.2.1 ECO function

Setting the ECO temperature

Press the ECO button for

3seconds

38°C

Set the temperature,

range: 30-60°C

e.g. 40°C

Setting the ECO ﬂow rate

Press the ECO button for

3seconds

38°C

Briefly press the ECO button 8.0l/min

Set the flow rate

4-15l/min

e.g.

6.0 l/min.

4.2.2 Setting the brightness of blue and red backlighting

The display on the appliance is equipped with background ligh-

ting. When you set a temperature up to 42.5°C, the background

lighting lights up blue; at temperatures of 43.0°C and above, the

display switches to red.

The display background lights up when you press a button, turn

the temperature selector or if water ﬂows through the appliance

at a ﬂow rate greater than the starting ﬂow rate.

If no water is drawn off or the appliance is not operated for 30se-

conds, the background lighting switches off (only if a deactivated

orientation light has been selected).

If water is drawn off for more than 15minutes, brightness will be

reduced (reduction only with setting >20%).

The brightness of both the red and blue light can be individually

adjusted in 5 stages.

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

Blue

Red

Select the brightness for the

red and blue lighting

100%

20%

4.2.3 Activating/deactivating the orientation light

The backlighting helps you ﬁnd your way in dark rooms. For this

purpose, you can set the lighting so it is constantly on. The orien-

tation light then lights up with the intensity of the set background

lighting.

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

OFF

Select "OFF"/"ON"

OFF:

ON:

deactivated

activated

4.2.4 Activating/deactivating/adjusting the childprooﬁng

function

You can set the appliance to a maximum temperature.

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

OFF

Select "OFF"/"ON".

OFF:

ON:

deactivated

activated

Briefly press the ECO button 43 °C

Setting the temperature

e.g. 36°C

OPERATION

Settings

ENGLISH

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4.2.5 Activating/deactivating the Wellness comfort function

You can permanently program a Wellness comfort function which,

after water has been drawn for three minutes, reduces the tem-

perature by 10°C and then increases it again after 10 seconds.

After a further 10seconds, the temperature is lowered again by

10°C and then raised again after 10seconds. This temperature

change continues for the entire period that water is being drawn.

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

OFF

Select "OFF"/"ON"

OFF:

ON:

deactivated

activated

4.2.6 Activating/deactivating/adjusting the automatic water

volume control

You can set the automatic water volume control function so that

the ﬂow rate is reduced to approx.4l/min once a speciﬁed volume

has been drawn off. This enables you to inﬂuence the amount of

water drawn as well as the duration of a shower. The selected

automatic water volume control only applies to the next draw-off.

Press the ECO button for

3seconds.

38°C

Press the ECO button briefly

several times.

OFF

Select "OFF"/"ON"

OFF:

ON:

deactivated

activated

When set to "ON", briefly

press the ECO button

80 l

Adjust the water volume

5-200 l

e.g. 150 l

4.2.7 Selecting the second line on the display

You can select what additional information is displayed in the

second line:

l/min Flow rate

kWh Energy consumption (you can set the values of these con-

sumption indicators to zero)

m³ Water volume (you can set the values of these consumpti-

on indicators to zero)

Time Time (if the power supply has been interrupted you will

need to reset the clock)

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

Select the display value for

the second line

Selected display

Setting the "energy consumption and water volume" consumption

indicator to zero.

In the INFO menu, press

button1 and button2 simul-

taneously when the corre-

sponding consumption value

appears on the display

0

4.2.8 Setting the time

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

Set the time

e.g. 12:15

Note:

Reset the time after

a power interrup-

tion.

4.2.9 Wireless remote control – checking, pairing, unpairing

The appliance can be controlled remotely by means of

a wireless remote control. The transmitter is waterpro-

of and can also be used whilst showering or bathing.

Up to four wireless remote controls can be combined.

The wireless remote control enables you to control the tempera-

ture of the appliance remotely from another location (e.g. from

the kitchen sink).

The wireless remote control has four buttons for selecting the

temperature (38°C and 55°C are ﬁxed settings; plus and minus

button for changing the temperature in 0.5°C stages). When a

signal is being sent to the appliance, the red LED on the wireless

remote control lights up.

If you press any button on the wireless remote control while the

appliance is in ECO mode, the ECO function is cancelled for the next

draw-off. ECO mode is resumed two minutes after the draw-off.

If the appliance is in standard mode, a constant temperature can

be selected via the wireless programming unit.

Wireless remote control check on the appliance

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

rc 1-4

Number of registered

wireless remote controls

(rc: remote control)

Pairing a wireless remote control with the appliance

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

rc 1

Press button1: Pairing phase

is activated.

Press any button on the wire-

less remote control.

Bar graph is shown.

Green LED flashes.

rc 2

Bar graph display goes

off.

Wireless remote control

is recognised

Unpairing a wireless remote control from the appliance

Press the ECO button for

3seconds

38°C

Press the ECO button briefly

several times

rc 2

In "rc" mode, press button2 rc 0: All wireless remote

controls are deregistered

OPERATION

Cleaning, care and maintenance

8 | PER 18/21/24 www.stiebel-eltron.com

4.2.10 Resetting to factory defaults

Press button1 and button2

simultaneously for 2seconds

Display ﬂashes to con-

ﬁrm.

Anti-scalding protection and registered wireless remote controls

are not reset (for factory defaults, see chapter "Speciﬁcation").

4.3 Settings on the wireless remote control

OFF

3s

D0000041708

Press 38°

Press 55°

Press +

Press -

38°C

55°C

Press 1x: Set value raised by 0.5°C.

Press 1x: Set value lowered by 0.5°C.

You can switch the appliance heater to OFF using the wireless

remote control. To do this, press the minus button for at least3se-

conds. Press any button to switch it back on.

4.4 Further functions

4.4.1 Dynamic anti-scalding protection

The appliance is equipped with dynamic anti-scalding protection.

The user who is ﬁrst to select a temperature on the appliance or

via the wireless remote control sets the temperature for the next

draw-off. No other user can increase the temperature above 43°C

in the following two minutes or during a draw-off or for two mi-

nutes following the end of a draw-off.

4.4.2 Anti-scalding protection

The qualiﬁed contractor can permanently limit the temperature

(see chapter "Troubleshooting/ Customer service mode"). This

prevents water from ﬂowing out of the appliance at temperatures

which could cause injury.

4.5 Recommended settings

Saving energy

The following recommended settings will result in the lowest

energy consumption:

- 38°C for hand washbasins, showers, bath

- 55°C for kitchen sinks

Thermostatic valve

If the appliance is being operated with a thermostatic valve, we

recommend setting the temperature on the appliance to maxi-

mum (temperature selector set to 60°C). You can then select the

required temperature at the thermostatic valve.

Following an interruption to the water supply

!

Material losses

Following an interruption of the water supply the appli-

ance must be recommissioned by carrying out the fo-

llowing steps, in order to prevent the destruction of the

bare wire heating system.

 Disconnect the appliance from the power supply by

removing the fuses/tripping the MCBs.

 Open the tap for one minute until the appliance and

its upstream cold water inlet line are free of air.

 Switch the mains power back on again.

5. Cleaning, care and maintenance

 Never use abrasive or corrosive cleaning agents. A damp

cloth is sufﬁcient for cleaning the appliance.

 Check the taps regularly. Limescale deposits at the tap out-

lets can be removed using commercially available descaling

agents.

6. Troubleshooting

Problem Cause Remedy

The appliance will not

start despite the DHW

valve being fully open.

There is no power.

Check the fuses/MCBs in

your fuse box/distributi-

on board.

The aerator in the tap or

the shower head is sca-

led up or dirty.

Clean and/or descale the

aerator or shower head.

Required temperature

>45°C is not achieved.

The water supply has

been interrupted.

Vent the appliance and

the cold water inlet line

(see chapter "Settings").

The cold water inlet tem-

perature is >45°C.

Reduce the cold water

inlet temperature.

The flow rate is too low.

ECO mode is activated

and the flow rate value in

ECO mode is set too low.

Set a higher ECO flow

rate.

It is not possible to set a

temperature higher than

43°C.

Dynamic anti-scalding

protection is enabled.

Is cancelled automati-

cally two minutes after

drawing has ceased.

If you cannot remedy the fault, notify your qualiﬁed contractor.

To facilitate and speed up your enquiry, please provide the serial

number from the type plate (000000-0000-00000):

Nr.: 000000-0000-00000

D0000041614

INSTALLATION

Safety

ENGLISH

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Wireless remote control battery change

Problem Cause Remedy

LED on the wireless

remote control flashes

during and after trans-

mission.

Battery in the wireless

remote control is flat.

Replace the battery.

!

Material losses

 Remove the old battery.

Any damage caused by a leaking battery is excluded from

the warranty.

 Open the housing of the wireless remote control by

unscrewing the two screws on the back and prising off the

casing.

 Change the battery; for battery type, see chapter "Speciﬁcati-

on/ Data table".

Note

The positive terminal of the battery must face away from

the PCB.

 Close the casing. When doing so, pay attention to the recess

on the edge of the lid. The recess determines the correct po-

sitioning of the lid and ensures the casing is tightly sealed.

Battery disposal

Never dispose of batteries with domestic waste. Spent

batteries may contain noxious substances that can be det-

rimental to the environment and human health. Dispose

of spent batteries through your dealer or via a central

recycling point for special waste.

INSTALLATION

7. Safety

Only a qualiﬁed contractor should carry out installation, commi-

ssioning, maintenance and repair of the appliance.

7.1 General safety instructions

We guarantee trouble-free function and operational reliability only

if original accessories and spare parts intended for the appliance

are used.

!

Material losses

Observe the maximum inlet temperature. Higher tem-

peratures may damage the appliance. You can limit the

maximum inlet temperature by installing a central ther-

mostatic valve.

WARNING Electrocution

This appliance contains capacitors which are discharged

when disconnected from the power supply. The capacitor

discharge voltage may brieﬂy reach >60VDC.

7.2 Shower operation

CAUTION Burns

 When supplying a shower, set the internal tempera-

ture limit to 55°C or lower; see chapter "Appliance

description / Customer service mode/ Anti-scalding

protection / Temperature limit menu".

CAUTION Burns

If the water supplied to the appliance is preheated, plea-

se note the following:

The internally adjustable temperature limit may be ex-

ceeded.

 Limit the temperature with an upstream central

thermostatic valve.

7.3 Instructions, standards and regulations

Note

Observe all applicable national and regional regulations

and instructions.

- The IP 25 (hoseproof) rating can only be ensured with a co-

rrectly ﬁtted cable grommet.

- The speciﬁc electrical resistivity of the water must not

fall below that stated on the type plate. In a linked water

network, observe the lowest electrical water resistivity

(see chapter "Speciﬁcation/ Application areas/ Conversion

table"). Your water supply utility will advise you of the speci-

ﬁc electrical water resistivity or conductivity.

INSTALLATION

Appliance description

10 | PER 18/21/24 www.stiebel-eltron.com

8. Appliance description

8.1 Standard delivery

The following are delivered with the appliance:

- Wall mounting bracket

- Threaded stud for wall mounting

- Installation template

- 2 twin connectors (cold water with shut-off valve)

- Flat gaskets

- Cable grommet (power cable from above/ below)

- Screws/ rawl plugs for securing the back panel to allow for

water connection on ﬁnished walls

- Mini FFB wireless remote control

For appliance replacement

- 2 tap extensions

Wireless remote control

OFF

3s

D0000041699

1 2 3

1 Transmitter incl. battery

2 Wall mounting bracket

3 Adhesive pad

9. Preparation

9.1 Installation location

!

Material losses

Install the appliance in a room free from the risk of frost.

 Always install the appliance vertically and near the draw-off

point.

The appliance is suitable for undersink and oversink installation.

Undersink installation

26�02�02�1345

1

2

1 Cold water inlet

2 DHW outlet

Oversink installation

12

26�02�02�1344

1 Cold water inlet

2 DHW outlet

Note

 Mount the appliance on the wall. The wall must have

sufﬁcient load bearing capacity.

9.2 Water installation

- No safety valve is required.

- Safety valves are not permissible in the DHW pipe.

 Flush the water line thoroughly.

Taps

Use appropriate pressure taps. Open vented taps are not permi-

ssible.

Note

Never use the shut-off valve in the cold water inlet to

reduce the ﬂow rate. It is intended for shutting off the

appliance.

Permissible water line materials

- Cold water inlet pipe:

Pipes made from galvanised steel, stainless steel, copper or

plastic

- DHW outlet line:

Pipes made from stainless steel, copper or plastic

!

Material losses

If plastic pipework systems are used, take into account

the maximum inlet temperature and the maximum pre-

ssure (see chapter "Speciﬁcation/ Data table").

Flexible water connection lines

 If the appliance is installed with ﬂexible water connection

lines, ensure that the pipe bends with bayonet ﬁttings do not

become twisted inside the appliance.

 Secure the back panel at the bottom with two additional

screws.

INSTALLATION

Installation

ENGLISH

www.stiebel-eltron.com PER 18/21/24 | 11

10. Installation

10.1 Standard installation

- Electrical connection from above; installation on unﬁnished

walls

- Water connection on unﬁnished walls

- Medium connected load is selected

For further installation options, see chapter "Alternative installa-

tion methods":

- Electrical connection from below on unﬁnished walls

- Electrical connection on ﬁnished walls

- Connecting a load shedding relay

- Water installation on ﬁnished walls

- Water connection on unﬁnished walls for appliance

replacement

- Operation with preheated water

- Installation of wireless remote control

Opening the appliance

D0000041615

 Open the appliance by releasing the snap lock.

NT

T-

so

X1

26�02�02�0762

 Remove the back panel by pressing the two locking hooks

and pulling the lower section of the back panel forwards.

Preparing the power cable

160

≥ 30

26�02�02�0887

Fitting the wall mounting bracket

26�02�02�0972

 Mark out the holes for drilling using the installation templa-

te. If the appliance is to be installed with water connections

on ﬁnished walls, also mark out the ﬁxing holes in the lower

part of the template.

 Drill the holes and secure the wall mounting bracket with

2screws and 2rawl plugs (screws and rawl plugs are not

part of the standard delivery).

 Fit the threaded stud provided.

 Fit the wall mounting bracket.

Fitting the cable grommet

26�02�02�0950

 Fit the cable grommet. For connecting cables >6mm², en-

large the hole in the cable grommet.

INSTALLATION

Installation

12 | PER 18/21/24 www.stiebel-eltron.com

Making the water connection

!

Material losses

Carry out all water connection and installation work in

accordance with regulations.

26�02�02�0948

 Seal and insert the twin connectors.

!

Material losses

Never use the shut-off valve in the cold water inlet to

reduce the ﬂow rate.

Preparing the back panel

!

Material losses

If you break open the wrong knock-out in the back panel

by mistake, you must use a new back panel.

18

kW

24

21

26�02�02�0884

 Break out the cable grommet knock-out in the back panel.

Deburr any sharp edges with a ﬁle if necessary.

Installing the appliance

18

kW

24

21

26�02�02�0885

 Push the back panel over the threaded stud and the cable

grommet. Pull the cable grommet by the locking hooks into

the back panel using pliers, until both locking hooks audibly

click into place.

 Remove the protective transport plugs from the water

connections.

 Press the back panel ﬁrmly into place and lock the ﬁxing tog-

gle by turning it clockwise through 90°.

D0000041925

 Screw the water connection pipes with ﬂat gaskets onto the

twin connectors.

!

Material losses

The strainer must be ﬁtted for the appliance to function.

 When replacing an appliance, check whether the

strainer is installed (see chapter "Maintenance").

INSTALLATION

Installation

ENGLISH

www.stiebel-eltron.com PER 18/21/24 | 13

Making the electrical connection

WARNING Electrocution

Carry out all electrical connection and installation work

in accordance with relevant regulations.

WARNING Electrocution

The connection to the power supply must be in the form

of a permanent connection in conjunction with the remo-

vable cable grommet. Ensure the appliance can be sepa-

rated from the power supply by an isolator that disco-

nnects all poles with at least 3mm contact separation.

WARNING Electrocution

Ensure that the appliance is earthed.

!

Material losses

Observe the type plate. The speciﬁed voltage must match

the mains voltage.

 Connect the power cable to the mains terminal (see chapter

"Speciﬁcation/ Wiring diagrams").

Re-plugging the coding card

In its delivered condition, the appliance is set to 21kW. When

changing to a different connected load, carry out the following

steps:

18

kW

24

21

18

kW

24

21

D0000037821

 Re-plug the coding card according to the selected connected

load (for selectable connected load and fuse protection of the

appliance, see "Speciﬁcation/ Data table").

 Tick the selected connected load on the type plate. Use a

ballpoint pen to do this.

Fitting the base part of the back panel

3

L

3’

4

L

2’

1

L

1’

2

L

NT C

T- sol

l

X11

26�02�02�1348

 Position the lower back panel on the main back panel and

click it into place.

 Align the mounted appliance by undoing the ﬁxing toggle,

aligning the power supply and back panel, and then re-tigh-

tening the ﬁxing toggle. If the back panel is not ﬂush with the

wall, the appliance can be secured at the bottom with two

additional screws.

10.2 Alternative installation methods

10.2.1 Electrical connection from below on unﬁnished walls

18

kW

24

21

26�02�02�0890

 Fit the cable grommet.

!

Material losses

If you break open the wrong knock-out in the back panel

by mistake, you must use a new back panel.

 Break out the cable grommet knock-out in the back panel.

Deburr any sharp edges with a ﬁle if necessary.

 Reposition the mains terminal in the appliance from the top

to the bottom.

 Push the back panel over the threaded stud and the cable

grommet. Pull the cable grommet by the locking hooks into

the back panel using pliers, until both locking hooks audibly

click into place.

 Press the back panel ﬁrmly into place and lock the ﬁxing tog-

gle by turning it clockwise through 90°.

INSTALLATION

Installation

14 | PER 18/21/24 www.stiebel-eltron.com

10.2.2 Electrical connection on ﬁnished walls

Note

This type of connection changes the IP rating of the appli-

ance.

 Change the type plate. Cross out "IP 25" and mark

the box "IP 24". Use a ballpoint pen to do this.

!

Material losses

If you break open the wrong knock-out in the back panel

by mistake, you must use a new back panel.

 Cleanly cut or break out the required cable entries in the

back panel (for positions, see chapter "Speciﬁcation/ Dimen-

sions and connections"). Deburr any sharp edges with a ﬁle if

necessary.

 Route the power cable through the cable grommet and co-

nnect it to the mains terminal.

10.2.3 Connecting a load shedding relay

When operating additional electric appliances, such as electric

storage heaters, install a load shedding relay in the distribution

board. The relay responds when the instantaneous water heater

starts.

!

Material losses

Connect the phase that switches the load shedding relay

to the indicated terminal of the mains terminal in the

appliance (see chapter "Speciﬁcation/ Wiring diagrams").

10.2.4 Water installation on ﬁnished walls

Note

This type of connection changes the IP rating of the appli-

ance.

 Change the type plate. Cross out "IP 25" and mark

the box "IP 24". Use a ballpoint pen to do this.

26�02�02�0765

 Fit water plugs with gaskets to seal the concealed

connections.

 Fit a suitable pressure tap.

26�02�02�1006

 Click the lower back panel section into place in the upper

section of the back panel.

 Secure the connection pipes to the appliance.

 Secure the back panel at the bottom with two additional

screws.

!

Material losses

If you break open the wrong knock-out in the back panel

by mistake, you must use a new back panel.

 Cleanly break out the knock-outs in the appliance cover. De-

burr any sharp edges with a ﬁle if necessary.

 Slide the lower back panel under the connection pipes of the

tap and click the lower back panel into place.

 Secure the connection pipes to the appliance.

10.2.5 Water installation on unﬁnished walls for appliance

replacement

If the existing twin connectors of the old appliance only protrude

from the wall by approx.16mm, you cannot use the twin co-

nnectors provided.

Note

With this connection, the cold water supply can only be

shut off within the domestic installation.

16

D0000041634

 Seal and ﬁt the screw-in tap extensions provided.

 Connect the appliance.

INSTALLATION

Commissioning

ENGLISH

www.stiebel-eltron.com PER 18/21/24 | 15

10.2.6 Operation with preheated water

You can limit the maximum inlet temperature by installing a cent-

ral thermostatic valve. For use in shower operation, the valve must

be set to a maximum of 55°C.

10.3 Completing the installation

 Open the shut-off valve in the twin connector or the cold

water inlet line.

10.4 Installation of wireless remote control

You can attach the transmitter to the wall using the wall mounting

bracket.

 Secure the wall mounting bracket to the wall using the adhe-

sive pad provided or a suitable countersunk screw (∅3mm

or less).

11. Commissioning

WARNING Electrocution

Commissioning must only be carried out by a qualiﬁed

contractor in accordance with safety regulations.

11.1 Initial start-up

D0000041617

 Open and close all connected draw-off valves several times,

until all air has been purged from the pipework and the

appliance.

 Carry out a tightness check.

 Activate the safety pressure limiter by ﬁrmly pressing the

reset button (the appliance is delivered with the safety pres-

sure limiter deactivated).

 Plug the temperature selector cable plug into the PCB.

 Fit the appliance cover, ensuring it clicks into place. Check

that the appliance cover is seated correctly.

 Switch the power supply ON.

 Check the appliance function.

Mini FFB wireless remote control

The wireless remote control is registered with the appliance at the

factory. If there is no data communication during commissioning,

carry out the pairing process as follows:

 Use the ECO button to switch to the comfort function "Wire-

less remote control (rc)"

 Press memory button1 on the appliance (the pairing phase

is activated, bar graph is shown on display).

 Then press a button on the wireless remote control.

Anti-scalding protection/ temperature limit

In customer service mode, you can limit the temperature to

between 31 and 60°C.

Appliance handover

 Explain the appliance function to users and familiarise them

with how it works.

 Make the user aware of potential dangers, especially the risk

of scalding.

 Hand over these instructions.

11.2 Recommissioning

Vent the appliance and the cold water inlet line (see chapter

"Settings").

See chapter "Initial start-up".

12. Appliance shutdown

 Isolate all poles of the appliance from the power supply.

 Drain the appliance (see chapter "Maintenance").

INSTALLATION

Troubleshooting

16 | PER 18/21/24 www.stiebel-eltron.com

13. Troubleshooting

WARNING Electrocution

To test the appliance, it must be supplied with power.

Fault Cause Remedy

The flow rate is too

low.

Strainer and/or aera-

tor are dirty

Clean the strainer and/or aerator.

The motorised valve

is faulty.

Check the motorised valve. Repla-

ce it if required.

Permanent error

display on the pro-

gramming unit

The sensor/PCB is

faulty.

Further analyse the fault in custo-

mer service mode (see chapter

"Customer service mode").

Communication

between the pro-

gramming unit and

the control unit is

faulty.

Check the programming unit and

the connecting cable.

The background

lighting in the pro-

gramming unit is

completely off.

No mains power

Check the fuses/MCBs in your

fuse box/distribution board.

Loose connecting

cable to the pro-

gramming unit

Reconnect the cable.

Safety pressure limi-

ter has triggered.

Remove the cause.

Open a downstream draw-off

valve for 1minute. This depressu-

rises and cools down the heating

system, protecting it against

overheating.

Activate the safety pressure limi-

ter at flow pressure by pressing

the reset button.

Faulty PCB. Check the PCB and replace if

required.

Heating does not

switch on/ no hot

water.

Heater is faulty.

Check the heater and replace it if

required.

Flow meter faulty or

not plugged in.

Check the connection.

Check the flow meter in the

customer service mode.

The high limit safety

cut-out has respon-

ded or suffered a

lead break.

Remove the cause.

Activate the high limit safety cut-

-out, replace the high limit safety

cut-out if required.

Error display only

appears when water

is being drawn off.

One phase has

dropped out.

Check the fuses/MCBs in your

fuse box/distribution board.

Inlet temperature

>45°C.

See chapter "Water installation";

limit inlet temperature if nece-

ssary.

Intermittent cold

water.

Wellness function

enabled.

Disable the Wellness function.

Brief drop in flow

rate

The appliance restarts automati-

cally when an adequate flow rate

has been detected.

Air detector re-

sponds (cold water

for approx.1min).

The appliance restarts automati-

cally after a delay.

13.1 Customer service mode

Activate/deactivate customer service mode with the SERVICE bu-

tton on the back of the user interface (connection to "T-set" must

be present). Use the ECO button to move to the next menu item

(see chapter "Settings/ Settings in the INFO menu").

Scroll through the respective submenu by turning the temperature

selector.

1

26�02�02�0920

13.1.1 Fault menu

This menu is only shown if there is a fault.

Code Meaning

E1, ELEC The electronic assembly is faulty.

Replace the electronic assembly.

E 3, ntc Check the electrical connection to the outlet sensor. Replace it

if required.

E 4, mot Check the electrical connection to the motorised valve. Replace

it if required.

13.1.2 Control menu

Code Meaning

C 1, 36.5°C Display of the current inlet temperature. If the cold water sen-

sor is faulty, a temperature of 1.0°C is displayed.

C 2, 47.5 °C Display of the current outlet temperature. If the cold water

sensor is faulty, a temperature of 65.0°C is displayed.

C 3, 6.8 l/min Display of the current flow rate.

C 4, 21.5 kW Display of the current power consumption.

13.1.3 Data menu

Code Meaning

d 1, 8042 Service code for customer support

d 2, 2341 Number of days, on which the appliance is connected to the

power supply.

d 3, 172h Heating time in hours.

d 4, 24 kW Maximum output in kW: This output may deviate from the

rated output, e.g. if the mains voltage is not 400V.

INSTALLATION

Maintenance

ENGLISH

www.stiebel-eltron.com PER 18/21/24 | 17

13.1.4 Anti-scalding protection/ Temperature limit menu

Code Meaning

OFF Anti-scalding protection/ Temperature limit OFF.

On Anti-scalding protection/ Temperature limit ON.

31-60°C Maximum selectable value on appliance when ON

Factory defaults (see chapter "Speciﬁcation").

After exiting customer service mode, you cannot change the set

maximum temperature via the user interface.

CAUTION Burns

If operating with preheated water, the set temperature

limit and anti-scalding protection may be ineffective.

In such cases, limit the temperature with an upstream

central thermostatic valve.

14. Maintenance

WARNING Electrocution

Before any work on the appliance, disconnect all poles

from the power supply.

Draining the appliance

The appliance can be drained for maintenance work.

WARNING Burns

Hot water may escape when draining the appliance.

 Close the shut-off valve in the twin connector or the cold

water inlet line.

 Open all draw-off valves.

 Undo the water connections on the appliance.

 Store the dismantled appliance in a room free from the risk

of frost, as water residues remaining inside the appliance can

freeze and cause damage.

Cleaning the strainer

26�02�02�0949

If dirty, clean the strainer in the threaded cold water ﬁtting. Close

the shut-off valve in the cold water inlet line before removing,

cleaning and reﬁtting the strainer.

15. Speciﬁcation

15.1 Dimensions and connections

395

100

485

325

45

5

93

226

190

50

112

190

35

c01

c06

b02

D0000017757

b02 Entry electrical cables I

c01 Cold water inlet Male thread G 1/2 A

c06 DHW outlet Male thread G 1/2 A

Alternative connection options

325

50

35

40

b03

b02

b04

D0000019778

b02 Entry electrical cables I

b03 Entry electrical cables II

b04 Entry electrical cables III

INSTALLATION



18 | PER 18/21/24 www.stiebel-eltron.com

15.2 Wiring diagrams

3/PE ~ 380-415 V

85�02�02�0005

1 Heating

2 High limit safety cut-out

3 Safety pressure limiter

Priority control with LR 1-A

85�02�02�0003�

2

1

1 Control cable to the contactor of the 2nd appliance (e.g.

electric storage heater).

2 Control contact drops out when switching the instantaneous

water heater on.

15.3 Factory settings

Wellness OFF

Automatic water volume

control

OFF/ 80 l

ECO 38 °C / 8 l/min

Childproofing OFF/ 43.0°C

Second line of the display l/min

Orientation light OFF

Backlighting blue/ red 100 %

15.4 DHW output

The DHW output is subject to the mains voltage, the appliance's

connected load and the cold water inlet temperature. The rated

voltage and rated output can be found on the type plate (see

chapter "Troubleshooting").

Connected load in kW 38 °C DHW output in l/min.

Rated voltage Cold water inlet temperature

380 V      

16.2 7.0 8.3 10.1 12.9

19 8.2 9.7 11.8 15.1

21.7 9.4 11.1 13.5 17.2

18 7.8 9.2 11.2 14.3

21 9.1 10.7 13.0 16.7

24 10.4 12.2 14.9 19.0

19.4 8.4 9.9 12.0 15.4

22.6 9.8 11.5 14.0 17.9

25.8 11.2 13.2 16.0 20.5

Connected load in kW 

Rated voltage Cold water inlet temperature

380 V      

16.2 5.1 5.8 6.6 7.7

19 6.0 6.8 7.8 9.0

21.7 6.9 7.8 8.9 10.3

18 5.7 6.4 7.3 8.6

21 6.7 7.5 8.6 10.0

24 7.6 8.6 9.8 11.4

19.4 6.2 6.9 7.9 9.2

22.6 7.2 8.1 9.2 10.8

25.8 8.2 9.2 10.5 12.3

15.5 Application areas/ Conversion table

Speciﬁc electrical resistivity and speciﬁc electrical conductivity

(see chapter "Data table").

Standard specifica-





25 °C

Resisti-

vity ρ ≥

Conductivity σ ≤ Resisti-

vity ρ ≥

Conductivity σ ≤ Resisti-

vity ρ ≥

Conductivity σ ≤

Ωcm mS/m μS/cm Ωcm mS/m μS/cm Ωcm mS/m μS/cm

900 111 1111 800 125 1250 735 136 1361

1000 100 1000 890 112 1124 815 123 1227

15.6 Pressure drop

Taps

Tap pressure drop at a flow rate of 10 l/min

Mono lever mixer tap, approx. MPa 0.04 - 0.08

Thermostatic valve, approx. MPa 0.03 - 0.05

Hand shower, approx. MPa 0.03 - 0.15

Sizing the pipework

When calculating the size of the pipework, an appliance pressure

drop of 0.1MPa is recommended.

15.7 Fault conditions

In the event of a fault, loads up to a maximum of 95°C at a pres-

sure of 1.2MPa can occur temporarily in the installation.

INSTALLATION



ENGLISH

www.stiebel-eltron.com PER 18/21/24 | 19

15.8 Test symbols

See type plate on the appliance.

15.9 Energy consumption data

Product datasheet: Conventional water heaters to regulation (EU)

no. 812/2013 and 814/2013

PER 18/21/24

233990

Manufacturer STIEBEL ELTRON

Load profile S

Energy efficiency class A

Energy conversion efficiency % 39

Annual power consumption kWh 479

Default temperature setting °C 60

Sound power level dB(A) 15

Special information on measuring efficiency Data at Pmax.

Daily power consumption kWh 2,186

15.10 Data tables

PER 18/21/24

233990

Electrical data

Rated voltage V 380 400 415

Rated output kW 16.2/19/21.7 18/21/24 19.4/22.6/25.8

Rated current A 27.6/29.5/33.3 29/31/35 30.1/32.2/36.3

Fuse protection A 32/32/35 32/32/35 32/32/40

Frequency Hz 50/60 50/60 50/-

Phases 3/PE

Max. mains impedance at 50Hz Ω 0.284 0.270 0.260

Specific conductivity σ

15

≤ (at ϑcold ≤25 °C) μS/cm 1111 1111 1000

Specific resistance ρ

15

≥ (at ϑcold ≤25°C) Ω cm 900 900 1000

Specific resistance ρ

15

≥ (at ϑcold ≤45°C) Ω cm 1200 1200 1300

Specific conductivity σ

15

≤ (at ϑcold ≤45°C) μS/cm 830 830 770

Connections

Water connection G 1/2 A

Application limits

Max. permissible pressure MPa 1

Max. inlet temperature for reheating °C 45

Values

Max. permissible inlet temperature °C 60

ON l/min >2.5

Pressure drop at flow rate MPa 0.08/0.1/0.13

Flow rate for pressure drop l/min 5.2/6.0/6.9

DHW delivery l/min 9.4/11.0/12.6

Δϑ on delivery K 26

Hydraulic data

Nominal capacity l 0.4

Versions

Adjustable connected load X

Temperature settings °C 30-60

Insulating block Plastic

Heating system heat generator Bare wire

Cover and back panel Plastic

Colour White

IP rating IP25

Dimensions

Height mm 485

Width mm 226

Depth mm 93

Weights

Weight kg 3.8

20 | PER 18/21/24 www.stiebel-eltron.com

INSTALLATION | GUARANTEE | ENVIRONMENT AND RECYCLING



GUARANTEE

ENVIRONMENT AND RECYCLING

Note

The appliance conforms to IEC 61000-3-12.

Mini FFB

Dimensions (H/W/D) excluding

wall mounting bracket

mm 50/50/17

Radio frequency MHz 868.3

Range inside a building incl.

one separating ceiling

m Approx. 25

Temperature setting range °C 30-60

IP rating to EN 60529 Shower

Bath

IP X5

IP X7

Battery type 1 x CR 2032

Guarantee

The guarantee conditions of our German companies do not

apply to appliances acquired outside of Germany. In countries

where our subsidiaries sell our products a guarantee can only

be issued by those subsidiaries. Such guarantee is only grant-

ed if the subsidiary has issued its own terms of guarantee. No

other guarantee will be granted.

We shall not provide any guarantee for appliances acquired in

countries where we have no subsidiary to sell our products.

This will not aect warranties issued by any importers.

Environment and recycling

We would ask you to help protect the environment. After use,

dispose of the various materials in accordance with national

regulations.

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