STIEBEL ELTRON DHX 15 Select User manual

OPERATION AND INSTALLATION
FUNCIONAMIENTO E INSTALACIÓN
Electronically Controlled Electric Tankless Water Heaters
Calentadores de Agua Electrónicos sin Tanque
»DHX15Select
Certified to ANSI/UL Std. 499
Conforms to CAN/CSA Std. C22.2 No. 64
Certificación ANSI/UL Std. 499
Conforme a CAN/CSA Std. C22.2 No.64
Tested and certified by WQA to NSF/ANSI372
for lead free compliance.
Probado y certificado por WQA NSF/ANSI 372 para
el cumplimiento de las regulaciones sin plomo.

2| DHX 15 Select www.stiebel-eltron-usa.com
CONTENTS
QUICK START GUIDE
SPECIAL INFORMATION
OPERATION
1. General information ___________________________________________ 5
1.1 Safety instructions__________________________________________________ 5
1.2 Other symbols in this documentation __________________________ 5
1.3 Units of measurement _____________________________________________ 5
2. Safety____________________________________________________________ 5
2.1 Intended use_________________________________________________________ 5
2.2 General safety instructions _______________________________________ 5
2.3 Test symbols _________________________________________________________ 6
2.4 Licenses / certificates ______________________________________________ 6
3. Register your product _________________________________________ 6
4. Water heater description______________________________________ 7
5. Settings and displays __________________________________________ 7
5.1 DHX Select user interface_________________________________________ 7
5.2 Using the display menus __________________________________________ 8
5.3 DHX Select display__________________________________________________ 8
5.4 Recommended settings ___________________________________________ 9
6. Cleaning, care and maintenance _____________________________ 9
7. Troubleshooting _______________________________________________10
INSTALLATION
8. Safety___________________________________________________________10
8.1 General safety instructions ______________________________________10
8.2 Instructions, standards and regulations ______________________10
9. Water heater description_____________________________________10
9.1 Standard delivery__________________________________________________10
10. Preparation ____________________________________________________11
10.1 Installation site_____________________________________________________11
10.2 Minimum clearances______________________________________________11
11. Installation_____________________________________________________11
11.1 Standard wall-mounted installation___________________________11
11.2 Water connections_________________________________________________12
11.3 Electrical connection______________________________________________13
11.4 Electrical connection with short power cable _______________13
11.5 Wiring block ________________________________________________________14
12. Commissioning ________________________________________________14
12.1 Internal anti-scalding protection via jumper slot ___________14
12.2 Initial start-up______________________________________________________14
12.3 Operation with preheated water _______________________________15
12.4 Recommissioning__________________________________________________15
13. Water heater shutdown ______________________________________15
14. Service information ___________________________________________15
15. Maintenance ___________________________________________________16
15.1 Draining the water heater _______________________________________16
15.2 Cleaning the filter screen ________________________________________16
16. Troubleshooting _______________________________________________ 17
17. Specification ___________________________________________________18
17.1 Dimensions and connections____________________________________18
17.2 Wiring diagram ____________________________________________________18
17.3 Hot water output___________________________________________________18
17.4 Application areas/conversion table ____________________________19
17.5 Fault conditions ____________________________________________________19
17.6 Data table ___________________________________________________________19
18. Spare parts ____________________________________________________20
19. Warranty _______________________________________________________21

QUICK START GUIDE
ENGLISH
www.stiebel-eltron-usa.com DHX 15 Select | 3
QUICK START GUIDE
Before turning on power to the water heater, you MUST flush all air out of the
system, then engage the AE3 safety switch. The unit will NOT operate until
the AE3 safety switch has been engaged.
1 Mount the unit to the wall (see section 11.1, “Standard wall-mounted installation”, pg. 11).
2 Hook up water connections (see section 11.2, “Water connections”, pg. 12).
3 Hook up electrical connections, but keep circuit breaker off. (See section 11.3, “Electrical connec-
tion”, pg. 13)
PLQ
12
D0000053277
4 Open and close all connected draw-off valves at least 5 times, for at least 3 minutes total,
until all air has been purged from the pipework and the water heater.
5 Ensure there are no water leaks from any plumbing connections.
D0000094561-b
6 Engage the AE3 safety switch by firmly pressing the white reset button until it clicks and fully
locks in place (the water heater is delivered with the safety switch disengaged).
7 Turn on power to the water heater at the circuit breaker in the breaker panel.

SPECIAL INFORMATION
4| DHX 15 Select www.stiebel-eltron-usa.com
SPECIAL INFORMATION
- Read this entire manual. Failure to follow all the
guides, instructions and rules could cause personal
injury or property damage. Improper installation, ad-
justment, alteration, service and use of this unit can
result in serious injury.
- This unit must be installed by a licensed electrician
and plumber. The installation must comply with all
national, state and local plumbing and electric codes.
Proper installation is the responsibility of the install-
er. Failure to comply with the installation and operat-
ing instructions or improper use voids the warranty.
- Save these instructions for future reference. The
installer should leave these instructions with the
consumer.
- If you have any questions regarding the installation,
use or operation of this water heater, or if you need
any additional installation manuals, please call our
technical service line at 800.582.8423 (USA and Can-
ada only). If you are calling from outside the USA or
Canada, please call USA 413.247.3380 and we will
refer you to a qualified Stiebel Eltron service repre-
sentative in your area.
- The water heater is suitable for supplying a shower in
many climates (shower operation). If the water heater
is also or exclusively used for shower operation, the
qualified contractor must adjust the temperature set-
ting range to 122°F (50°C) or less using the internal
anti-scalding protection on the water heater. When
using preheated water, it must be ensured that the
inlet temperature does not exceed 131°F (55 °C).
- Ensure the water heater can be separated from the
power supply by a circuit breaker that disconnects all
poles with at least 1/8˝ (3mm) contact separation.
- The specified voltage must match the power supply.
See the type plate on the right-hand side of the water
heater for full information.
- CAUTION: DO NOT INSTALL IN A BATH ENCLOSURE OR
SHOWER STALL.
DO NOT CONNECT TO A SALT-REGENERATED WATER
SOFTENER OR A SALT-WATER WATER SUPPLY.
FOR USE ON AN INDIVIDUAL BRANCH CIRCUIT ONLY.
CAUTION: CONNECT ONLY TO A CIRCUIT PROTECTED
BY A CLASS A GROUND FAULT INTERRUPTER
USE BONDING CONDUCTOR IN ACCORDANCE WITH
THE CANADIAN ELECTRICAL CODE, PART I
- The water heater must be properly grounded. See
section 17.2, “Wiring diagram,” pg. 18.
- The water heater must be permanently connected to
fixed wiring. For use on an individual branch circuit
only. See section 17.2, “Wiring diagram,” pg. 18.
- Secure the water heater as described in chapter 11,
“Installation”, pg. 11.
- Observe the minimum permissible water supply
pressure of 26.1 psi (1.8 bar). See section 17.6, “Data
table,” pg. 19.
- Observe the maximum permissible water supply
pressure of 145 psi (10 bar). See section 17.6, “Data
table,” pg. 19.
- Drain the water heater as described in section 15.1,
“Draining the water heater”, pg. 16.

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 water
heater 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.
f 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 in-
jury 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-serious
or minor injury.
1.2 Other symbols in this documentation
Note
General information is identified by the adjacent symbol.
f Read these texts carefully.
Symbol Meaning
Material losses
(water heater damage, material losses, and installation site
damage)
f 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 inches (millimeters) unless
otherwise stated.
2. Safety
2.1 Intended use
This water heater is suitable for heating domestic hot water or for
reheating preheated water. The water heater can supply one or
more draw-off points.
Water will not be reheated if the maximum inlet temperature for
reheating is exceeded.
The water heater is intended for domestic use. It can be used safely
by untrained persons. The water heater can also be used in non-do-
mestic environments, e.g. in small businesses, as long as it is used
in the same way.
Any other use beyond that described shall be deemed inappropriate.
Observation of these instructions and of the instructions for any
accessories used is also part of the correct use of this water heater.
2.2 General safety instructions
DANGER: Burns
Water temperatures over 125 °F (52°C) can cause severe
burns instantly or death from scalding. A hot water scald-
ing potential exists if the thermostat on the water heater
is set too high. Households with small children, disabled
or elderly persons may require that the thermostat be set
at 113°F (45 °C) or lower to prevent possible injury from
hot water.
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.
!
!

OPERATION
Register your product
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CAUTION: Burns
During operation, the tap can reach temperatures up to
149°F (65°C).
There is a risk of scalding at outlet temperatures in excess
of 110°F (43 °C).
!
DANGER: Injury
Please read and follow these instructions. Failure to follow
these instructions could result in serious personal injury
or death.
!
CAUTION: DO NOT INSTALL IN A BATH ENCLOSURE
OR SHOWER STALL. DO NOT CONNECT TO A
SALT-REGENERATED WATER SOFTENER OR A WATER
SUPPLY OF SALT WATER.
FOR USE ON AN INDIVIDUAL BRANCH CIRCUIT ONLY.
CAUTION: CONNECT ONLY TO A CIRCUIT PROTECTED BY A
CLASS A GROUND FAULT INTERRUPTER
USE BONDING CONDUCTOR IN ACCORDANCE WITH THE CA-
NADIAN ELECTRICAL CODE, PART I
DANGER: Electrocution
Before proceeding with any installation, adjustment,
alteration, or service of this appliance, all circuit break-
ers and disconnect switches servicing the appliance
must be turned off. Failure to do so could result in seri-
ous personal injury or death.
DANGER: Electrocution
Never remove the water heater’s cover unless the elec-
tricity servicing the water heater is turned off. Failure to
do so could result in personal injury or death.
WARNING Electrocution
The connection to the power supply is only permissible as
a permanent connection in conjunction with a ¾˝Romex
clamp. Ensure the water heater can be separated from
the power supply by an isolator that disconnects all poles
with at least 1/8˝(3mm) contact separation.
!
WARNING: Injury
Where children or persons with limited physical, sensory
or mental capabilities are to be allowed to control this
water heater, ensure that this will only happen under su-
pervision or after appropriate instructions by a person re-
sponsible for their safety. Children should be supervised to
ensure that they never play with the water heater.
!
DAMAGE TO THE WATER HEATER AND THE ENVIRON-
MENT:
The water heater must be installed by a licensed electrician
and plumber. The installation must comply with all nation-
al, state and local plumbing and electric codes.
Service of the water heater must be performed by qualified
service technicians.
!
DAMAGE TO THE WATER HEATER AND THE ENVIRON-
MENT:
Supply this appliance only from a grounded system. A
green terminal (or a wire connector marked “G”, “GR”,
“GROUND”, OR “GROUNDING”) is provided for wiring the
appliance. To reduce the risk of electric shock, connect
this terminal or connector to the grounding terminal of the
electric service or supply panel with a continuous copper
wire in accordance with the electrical installation code.
Where children or persons with limited physical, sensory or mental
abilities are allowed to use this water heater, we recommend a
permanent temperature limit. The following limitation options are
available:
- DHX Select - user adjustable: Temperature limit (childproofing)
- Qualified contractor adjustable: “Internal anti-scalding
protection”
!
Material losses
The user should protect the water heater against frost.
2.3 Test symbols
See type plate on the water heater.
2.4 Licenses / certificates
- UL (USA) Std. 499
- CSA (Canada) Std. C22.2 No. 64
3. Register your product
You must register this product within 90 days of pur-
chase on our web site in order to activate the standard
warranty. Go to our web site at
www.stiebel-eltron-usa.com and click on “Register
Your Product.”
Before beginning the registration process, we suggest that you
gather the necessary information which will be as follows:
Type, Example: DHX 15 Select (from the label that is on the unit)
Number listed after “Nr.”
Place of Purchase
Purchase Date
First & Last Name
Email address
Physical Address
Phone Number
Installation Date
If you have any questions concerning the registration pro-
cess or warranty, please contact Stiebel Eltron USA directly at
800.582.8423.

OPERATION
Water heater description
ENGLISH
www.stiebel-eltron-usa.com DHX 15 Select | 7
4. Water heater description
The water heater switches on automatically as soon as a hot water
valve at a tap or other draw-off point is opened. DHX heats water as
it flows through the unit. When the tap is closed, the water heater
switches off automatically.
From the activation flow rate, the electronic control unit controls the
correct heating output using only the minimum amount of power
necessary, subject to the temperature selected, the current incoming
cold water temperature, and the flow rate.
DHX Select models are electronically controlled tankless water heat-
ers, and maintain a consistent outlet temperature. This is irrespec-
tive of the inlet water temperature, up to the maximum output of
the water heater.
DHX Select models feature Advance Flow Control™, a technology
patented by Stiebel Eltron in Germany (patent no. DE 3805441 C2).
When the maximum output of a DHX Select model is met, rather
than deviate from the setpoint temperature and deliver cooler water,
DHX Select models use an electronically-controlled motorized valve
to slightly reduce the flow of water only as much as is necessary
to maintain the user-selected temperature. When the demand can
again be fully met, the motorized valve returns to the fully open posi-
tion, allowing the full flow rate. This ensures uninterrupted comfort,
and hot water delivered at the desired temperature at all times.
If the water heater is operated with preheated water, and the inlet
temperature exceeds the selected set temperature, the inlet tem-
perature will be displayed on the second row of the screen and will
flash. The water is not heated further.
DHX Select models are equipped with functions to permanently limit
the temperature (childproofing).
DHX Select models feature a backlit display that switches on auto-
matically as soon as water flows through the unit, or if a change is
made at the user interface. The backlight switches off automatically
if no changes are made for 30seconds, or 5seconds after hot water
stops being drawn.
DHX Select models allow the user to save different preset tempera-
tures and apply them quickly.
Domestic Hot Water (DHW) temperature
The DHW outlet temperature can be variably adjusted from 68–140°F
(20–60°C). The selected temperature is displayed.
Heating system
The Direct Coil™heating system is comprised of a pressure-tested,
glass-reinforced polyamide heating chamber with a nichrome wire
direct heating coil. It is suitable for hard and soft water areas and
is largely insusceptible to scale build-up. The Direct Coil™heating
system ensures rapid and efficient DHW production.
Note
The water heater is equipped with an air detector that
largely prevents damage to the heating system. If, during
operation, air is drawn into the water heater, the water
heater shuts down the heating output for one minute to
protect the heating system.
5. Settings and displays
5.1 DHX Select user interface
3
2
4
7
5
6
1
1 Backlit display
2 Temperature memory keys
3 Operating LED (flashes when output limit is reached)
4 Control knob
5 Main display | info display | parameter display
6 Segment display [10–100%]
7“T
max” button
5.1.1 DHX Select display overview
1
2
3
4
5
1Digitdisplay
2 Power capacity status
3T
max indicator
4 Temperature unit indicator
5 Display-lock indicator

OPERATION
Settings and displays
8| DHX 15 Select www.stiebel-eltron-usa.com
5.2 Using the display menus
The DHX Select features an interactive display that allow for user
customization to increase the level of comfort for the user.
The menu structure is designed in an intuitive, linear way to make
it as navigable as possible.
5.2.1 DHX Select user input
User input
Tmax button (pressing or holding this button
performs different functions)
Preset 1 button (pressing or holding this button
performs different functions)
Preset 2 button (pressing or holding this button
performs different functions)
Control knob (turn knob to change settings)
5.3 DHX Select display
The DHX Select display features a temperature and power capacity
display. The display is backlit and will illuminate whenever user
input is detected. The backlight will time out and deactivate if no
user input has been detected for 30 seconds.
For the name of each display element on the DHX Select, consult
section 5.1.1, “DHX Select display overview”, pg. 7.
5.3.1 Base display
The base display shows the current temperature setpoint in your
preferred temperature unit. The bar below the temperature shows
the current operating capacity. As the hot water demand fluctuates,
the power capacity status will change to show between 0 and 10
segments. The display below shows that the water heater is oper-
ating at 40% of full capacity.
All other menu displays will revert back to the base display either
after a 15-second period of time without user input, or after a 5-sec-
ond hold of the Tmax button.
Changing the setpoint temperature
Temperature settings
Range Increment Range Increment
68–140°F 1°F 20–60°C. 0.5°C
The setpoint temperature can be set between 68 °F (20°C) and 140°F
(60 °C).
The setpoint can be increased by turning the control knob clockwise,
and decreased by turning it counter-clockwise. The water heater
can be deactivated while still powered by turning the control knob
counter-clockwise, past the 68 °F (20 °C) setting.
5.3.2 Parameters menu
While at the base display, holding the Tmax button for 5 seconds will
advance the display to the first parameter menu.
Tmax parameter setting
The first parameter menu sets the value for Tmax. The value of Tmax
acts as a high temperature limiter. If the Tmax value is set, the set-
point of the water heater cannot be set above the Tmax value. This
feature is useful in scenarios where scalding from hot water is a
concern.
At the Tmax setting menu, the display will flash, indicating that the
value can be changed by rotating the control knob. The Tmax value
can be increased by turning the control knob clockwise, and de-
creased by turning it counter-clockwise. The Tmax value can be de-
activated by turning the control knob counter-clockwise, past the
68 °F (20 °C) setting. The display will read “Off” if Tmax is inactive.
If the Tmax symbol is visible at the base display, then the Tmax func-
tion is active and is limiting the maximum allowable temperature
to the preset level.
Pressing the Tmax button once while at this display will move the
display onto the temperature units parameter setting.

OPERATION
Cleaning, care and maintenance
ENGLISH
www.stiebel-eltron-usa.com DHX 15 Select | 9
Temperature units parameter setting
The DHX Select is capable of displaying temperature in either Fahr-
enheit or Celsius.
The current unit will be shown and the display will be flashing to
indicate that the value can be changed. Rotate the control knob to
change the value between Fahrenheit and Celsius.
Pressing the Tmax button once while at this display will move the
display onto the display-lock parameter setting.
Display-lock parameter setting
The display can be locked to prevent changes to the temperature set-
point. This menu will flash, indicating that the value can be changed
by rotating the control knob. While the display shows “Off”, the lock
is not active. The lock is active when it reads “On”.
If the display-lock parameter is set to “On” and the user either holds
the Tmax button for 5 seconds or lets the display time out for 15
seconds, the display-lock will become active.
If the display-lock is active, a lock symbol will appear on the base
display, and no parameters can be changed. In order to disable the
lock, hold the Tmax button for 12 seconds. The lock will disappear
from the display and all parameters can be changed again.
Pressing the Tmax button once while at the display-lock parameter
setting menu will move the display back onto Tmax parameter setting
menu.
5.3.3 Returning to the base display
While navigating the display and on any menu other than the base
display, holding the Tmax button for 5 seconds will return the display
to the base display. Additionally, the display will revert to the base
display after a 15-second period with no user input.
5.4 Recommended settings
Your electric tankless water heater offers maximum precision and
convenience for DHW production. Should you nonetheless operate
the water heater with a thermostatic valve, we recommend that you:
f Adjust the set temperature on the water heater to over 122 °F
(50°C). Then set the required set temperature on the thermo-
static valve.
Saving energy
The following recommended settings will result in the lowest energy
consumption:
- 100 °F (38 °C) for hand washbasins, showers, bath
- 131°F (55°C) for kitchen sinks
Internal anti-scalding protection (qualified contractors)
If required, the qualified contractor can set a permanent tempera-
ture limit, for example in nurseries, hospitals,etc., see section 12.1,
“Internal anti-scalding protection via jumper slot”, pg. 14.
Recommended setting for operation with a thermostatic valve
and water preheated by solar energy
f Set the temperature at the water heater to the maximum
temperature.
Following an interruption to the water supply
!
Material losses
To ensure that the Direct Coil™heating system is not dam-
aged following an interruption to the water supply, the
water heater must be restarted by taking the following
steps:
f Check the supply pressure. The reading on the gauge
should read more than 26.1psi, but not more than
145psi.
f Disconnect the water heater from the power supply by
turning off the connected circuit breaker.
f Open and close all connected draw-off valves at least 5
times, for at least 3 minutes total, until all air has been
purged from the pipework and the water heater.
f Switch the power back at the circuit breaker back ON.
6. Cleaning, care and maintenance
f Never use abrasive or corrosive cleaning agents. A damp cloth
is sufficient for cleaning the water heater.
f Check the taps regularly. Limescale deposits at the tap outlets
can be removed using commercially available descaling agents.

INSTALLATION
Troubleshooting
10 | DHX 15 Select www.stiebel-eltron-usa.com
7. Troubleshooting
Problem Cause Solution
The water heater will not
start despite the DHW
valve being fully open
There is no power Check to ensure circuit
breaker in breaker panel
hasn’t tripped. Reset if
necessary
The white AE3 safety
switch has not been en-
gaged during initial start-
up. Activate if necessary
(see section 12.2.1, “Initial
AE3 safety switch activa-
tion”, pg. 14). If the AE3
switch has tripped after
initial installation, contact
a qualified contractor to
fix the cause
The aerator in the tap or
the shower head is scaled
up or dirty
Clean and/or descale the
aerator or shower head
The water supply has
been interrupted
Vent the water heater and
the cold water inlet line
When hot water is being
drawn off, cold water
flows for a short period
The air detector detects
air in the water. It switch-
es off the heating output
briefly
The water heater restarts
automatically after 1min-
ute
Boiling noises are heard
during operation
The water heater has not
been vented
Vent the water heater (see
section 12.2, “Initial start-
up”, pg. 14)
The supply pressure is
too low
Ensure that the minimum
supply pressure of 26.1
psi is met, and that max
pressure doesn’t exceed
145 psi (see section 17.6,
“Data table”, pg. 19)
The required temperature
cannot be set
Internal anti-scalding pro-
tection is active
The internal anti-scalding
protection can only be
adjusted by qualified con-
tractors
If you cannot solve the problem, contact your qualified contractor.
To facilitate and speed up your inquiry, please provide the serial
number from the type plate (000000-0000-000000). For live technical
assistance, please contact us at 800.582.8423. Alternatively, you may
email us at [e-mail]
Nr.: 000000-0000-00000
D0000094552-b
INSTALLATION
8. Safety
Only a qualified contractor should carry out installation, commis-
sioning, maintenance and repair of the water heater.
8.1 General safety instructions
We guarantee trouble-free function and operational reliability only
if original accessories and spare parts intended for the water heater
are used.
!
Material losses
Observe the maximum inlet temperature. Higher tempera-
tures may damage the water heater. You can limit the max-
imum inlet temperature by installing a central thermostatic
valve.
WARNING Electrocution
This water heater contains capacitors which are discharged
when disconnected from the power supply. The capacitor
discharge voltage may briefly exceed60VDC.
8.2 Instructions, standards and regulations
Note
Observe all applicable national and regional regulations
and instructions.
- The electrical resistivity of the water must not fall below that
stated on the type plate. In a linked water network, factor in
the lowest electrical resistivity of the water. Your water supply
utility will advise you of the electrical resistivity or conductivity
of the water in your area.
9. Water heater description
9.1 Standard delivery
The following are delivered with the water heater:
- Filter screen, factory installed in cold water inlet
- Jumper for anti-scalding protection, attached
- Jumper, spare, attached
- 2 x mounting screws
- 2 x wall anchors