Navien NCB700-24L Guide

Version: 1.00 (October, 2020)
Getting Service
If your boiler requires service, you have several options for getting service:
●Contact an official Technical Assistance Service (TAS) at 0844 332 2323 or go to the website
(www.navien.co.uk).
For warranty service, always contact an official Technical Assistance Service (TAS) first.
●Contact the technician or professional who installed your boiler.
●Contact a Gas Safe Registered engineer.
When contacting an official Technical Assistance Service (TAS), please have the following
information available:
●Model number
●Serial number
●Date purchased
●Installation location and type
●Error code, if any appears on the front panel display
Navien LTD
Building 2, Guildford Business Park, Guildford, GU2 8XH
TEL [phone] www.navien.co.uk
Condensing Combi Boiler
User’s Information
Manual

User’s
Information
Manual
●These appliances are for use with natural gas or LPG.
(An LPG conversion kit is included with the boiler.)
●Type: B23-B33-B53-C13-C33-C43-C53-C63-C83
Gas Model GC Number
Natural Gas
NCB700-24L
NCB700-28L
NCB700-34L
NCB700-40L
LPG
NCB700-24L
NCB700-28L
NCB700-34L
NCB700-40L
Keep this manual near this boiler for future reference
whenever maintenance or service is required.
Condensing Combi Boiler
WARNING
If the information in these instructions is not followed exactly, a fire or explosion
may result, causing property damage or personal injury.
– Do not store or use petrol or other flammable vapours and liquids in the vicinity of this or
any other appliance.
– WHAT TO DO IF YOU SMELL GAS
●Do not try to light any appliances.
●Do not touch any electrical switch; do not use any phone in your building.
●Immediately call the National Gas Emergency Helpline on (Freephone) 0800 111999 or your gas
supplier from a neighbour’s phone. Follow the instructions received.
– Installation and service must be performed by a Gas Safe registered installer, service
agency or the gas supplier.

2 Contents
Contents
1. Safety Information 3
2. About the Boiler 7
2.1 Description of the Boiler 7
2.2 Parts of the Boiler 7
2.3 Using the Front Panel 8
3. Operating the Boiler 10
3.1 Turning the Boiler On or Off 10
3.2 Adjusting the Temperature 10
3.3 Viewing Basic Information 11
3.4 Resetting the Boiler 12
4. Troubleshooting 13
4.1 Solving Basic Problems 13
4.2 Understanding Error Codes 14
Warranty 15
ErP Information 16

Safety Information 3
B. BEFORE OPERATING smell all around
the appliance area for gas. Be sure to
smell next to the floor because some
gases are heavier than air and will
settle on the floor.
WHAT TO DO IF YOU SMELL GAS
●Do not try to light any appliances.
●Do not touch any electric switch; do
not use any phone in your building.
●Immediately call the National Gas
Emergency Helpline on (Freephone)
0800 111999 or your gas supplier
from a neighbour’s phone. Follow
the instructions received.
●Do not return to your home until
advised to do so.
C. Do not use this appliance if any part
has been under water. Immediately
call a qualified service technician to
inspect the appliance and to replace
any part of the control system and
any gas control which has been under
water.
WARNING
This appliance can be used by children
aged from 8 years and above and
persons with reduced physical, sensory
or mental capabilities or lack of
experience and knowledge if they have
been given supervision or instruction
concerning use of the appliance in a
safe way and understand the hazards
involved. Children shall not play with
the appliance. Cleaning and user
maintenance shall not be made by
children without supervision.
The following safety symbols are used in this manual. Read and
follow all safety instructions in this manual precisely to avoid
unsafe operating conditions, fire, explosion, property damage or
personal injury. Keep this manual for future reference.
DANGER
Indicates an imminently hazardous
situation which, if not avoided, could
result in severe injury or death.
WARNING
Indicates a potentially hazardous
situation which, if not avoided, may
result in injury or death.
CAUTION
Indicates a potentially hazardous
situation which, if not avoided, could
result in property damage.
WARNING
If you do not follow these instructions
exactly, a fire or explosion may result
causing property damage or personal
injury.
A. This appliance does not have a pilot.
It is equipped with an ignition device
which automatically lights the burner.
Do not try to light the burner by hand.
1. Safety Information

4 Safety Information
Water
Temperature
Time in which a young child can suffer
a full thickness (3rd degree) burn
70°C Less than 1 second
60°C 1 second
55°C 10 seconds
49°C 10 minutes
37°C Very low scald risk
WARNING
●Shut off the gas supply if the boiler is
damaged.
Have your installer or plumber show
you the location of the gas shut off
valve and demonstrate how to close
the valve. If the boiler is damaged as a
result of overheating, fire, flood, or any
other reason, close the manual shut
off valve and do not operate the boiler
again until it has been inspected by a
qualified technician.
●Do not store or use petrol or other
flammable liquids near this boiler.
Doing so may result in fire or explosion.
●Do not place combustibles, such as
newspapers or laundry, near the
boiler or flue system.
Doing so may result in a fire.
DANGER
HOT
BURN
To prevent burns:
●Use the lowest operating temperature
setting necessary to provide
comfortably hot water.
●If your household has children or
elderly or disabled residents, consider
using a lower temperature setting.
●Read all the instructions in this
manual carefully before changing the
temperature setting.
●Feel the water before using it on
children, the elderly, or the disabled.
DANGER
This boiler’s water temperature is set to
49°C at the factory for your safety and
comfort. Increasing the temperature
increases the risk of accidental scalding.
Water temperatures at or above 52°C
can cause instant scalding or severe
burns. Before you decide to change the
temperature setting, read the following
charts carefully.

Safety Information 5
CAUTION
●Do not attempt to repair or replace
any part of the boiler, unless it is
specifically recommended in this
manual.
For all other service, contact an
authorised technician or licensed
professional. Improper adjustments,
alterations, service, or maintenance
may lead to property damage or
personal injury, and will void your
warranty.
●Do not operate the boiler if you feel
something is wrong with it.
Doing so may result in product damage
or personal injury.
●Do not allow children to operate or
access the boiler.
Doing so may result in product damage
or personal injury.
●Do not attempt to change the DHW
water temperature while the boiler is
being used.
Doing so may result in personal injury.
●Do not turn on the boiler unless
the water and gas supplies are fully
opened.
Doing so may damage the boiler.
●Do not turn on the water if the cold
water supply shut-off valve is closed.
Doing so may damage the boiler.
●Do not use this boiler for anything
other than its intended purpose, as
described in this manual.
●Do not place or use hair sprays, spray
paints, or any other compressed
gases near the boiler or flue system,
including the flue termination.
Doing so may result in fire or explosion.
●Do not operate the boiler with the
front cover opened.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may
result in property damage or personal
injury.
●Do not operate this boiler without
proper flue system.
Doing so may result in fire or carbon
monoxide (CO) poisoning, which may
result in property damage or personal
injury. Inspect the flue termination and
air intake supply annually to ensure
proper operation of the boiler. Turn
off and discontinue use of the boiler
if any of the flue pipes, flue elbows, or
intake pipes are damaged in any way,
separated at a joint, or show evidence
of corrosion, rusting, or melting.
●Do not touch the power cord or
internal components of the boiler
with wet hands.
Doing so may result in electric shock.
●Do not make any electrical
connections before turning off the
electrical power supply at service
entrance panel.
Doing so may result in severe personal
injury.

6 Safety Information
●Do not remove the front cover unless
the power to the boiler is turned off
or disconnected.
Failure to do so may result in electric
shock.
●When servicing the controls, label all
wires prior to disconnecting them.
Failure to do so may result in wiring
errors, which can lead to improper or
dangerous operation.
●Do not use unapproved replacement
or accessory parts.
Doing so may result in improper or
dangerous operation and will void the
manufacturer’s warranty.
●Do not place anything in or around
the flue terminals, such as a clothes
line, that could obstruct the air flow
in or out of the boiler.
●This boiler has been approved for
use in the UK and Ireland only.
Using the boiler in any other country
will void the manufacturer’s warranty.
●Should overheating occur or the gas
supply fail to shut off, turn off the
manual gas valve to the appliance.
EC Conformity Declaration
0063
Navien, hereby declares that the boiler models:
NCB700-24L, NCB700-28L, NCB700-34L, NCB700-40L
to which this declaration refers, conform to and comply with
the essential requirements of the following applicable European
Standards and Directives.
Gas appliances: Regulation (EU) 2016/426
Standards EN15502-1, EN15502-2-1 and EN437
Boiler Efficiency: Directive 92/42/EEC
Regulation (EU) No.813/2013
Standards EN15502-1, EN15502-2-1
Low voltage: Directives 73/23/EEC and
93/68/EEC Standards EN 60335-1, EN 60335-2-30,
EN 60335-2-51, EN 50165
Electro-magnetic Compatibility: Directive 2004/108/EC
Standards EN 55014
Pressure Vessels: Directive 97/23/EEC
Navien, manufactures its products using a Quality Assurance
system in compliance with Standard EN-ISO 9001:2000.

About the Boiler 7
2.2 Parts of the Boiler
Front View
Coaxial
(Intake/Exhaust)
Bottom View
a
b
c
d
f
g
h
e
#Description
aGas connection
bCondensate water outlet
cDHW hot water outlet connection
dSpace heating supply connection
eReturn adapter filter
fCold water inlet connection
gPump drain plug
hCentral heating return connection
2.1 Description of the Boiler
The Navien NCB700 boiler is available in 4 models:
NCB700-24L, NCB700-28L, NCB700-34L, NCB700-40L.
The main features are as follows:
●Power Interruption: When the power is restored after a power
failure, the boiler will automatically start and return to normal
operation. A manual reset is not required.
●Freeze Protection: A sensor inside the boiler automatically
detects the temperature and, if necessary, initiates a safety
heating cycle to prevent internal equipment damage due to
freezing temperatures.
●Short-Circuit Protection: Any short-circuit occurring in the
boiler’s electrical circuit immediately blows the internal glass
fuses and automatically cuts off the gas supply.
●Lightning Protection: Each boiler is specially grounded, both
internally and externally, to protect against lightning strikes.
●Carbon Monoxide Protection: The boiler is designed to
maintain a safe air-to-gas ratio and combustion rate. This
function is continuously monitored by the boiler’s air ratio
control module.
●Thermostat Control Failure: Should the thermostat fail to
function properly, the boiler’s gas supply will be shut off
automatically as a safeguard.
●Auto Fan Detection: The rotation of the fan is automatically
detected and controlled. Fan failure will stop the operation of
the boiler.
●Boiling Prevention: Excessive temperatures will automatically
stop the boiler.
2. About the Boiler

8 About the Boiler
2.3 Using the Front Panel
The front panel allows you to adjust the temperature and view the operating status or error codes. Remove the protective sheet from the
front panel before using it.
2.3.1 Icons and Digital Display
The icons and digital display on the front panel provide important
information required for the boiler’s operation. Refer to the following
table for detailed information.
b
a
d
f
c
g
i
k
h
j
l
e
a
Outdoor temperature
compensation (OTC)
Displayed when the outdoor
temperature compensation (OTC) is
enabled.
b
Combustion
Displayed when the burner is
combusting.
c
System fault
Displayed when a system fault is
detected.
d
Anti-freeze
Displayed when the boiler is operating
in anti-freeze mode.
e
Schedule programming mode
Displayed when the boiler’s schedule
programming operation is set.
f
DHW preheat
Displayed
when the DHW
preheat feature
is enabled.
DHW
preheat
(Always ON)
DHW
Intelligent
g
Central heating demand
Indicates the central heating
demand is present.
h
DHW demand
Indicates that DHW demand is
present.
i
Central heating set temperature
When the central heating
temperature is set: Displays the
currently set central heating
temperature.
When the central heating
temperature is not set: Displays the
current supply water temperature.
j
DHW set temperature
When the DHW temperature is set:
Displays the currently set DHW
temperature.
When the DHW temperature is not set:
Displays the current supply water
temperature when using the DHW
thermostat.
Displays the current DHW tank
temperature when using the DHW
sensor.
kOutdoor temperature
Displays the outdoor temperature. l
System pressure
Displays the internal water pressure of
the boiler system.

About the Boiler 9
2.3.2 Buttons
Using the buttons on the front panel, you can turn on or off the boiler,
monitor the current operation status, and set the values required
for the boiler’s operation, such as central heating and DHW supply
temperatures. Refer to the following table for detailed information.
a
b
c
d
e
f
aMenu button
Access to the Main menu screen. bBack button Access to the previous screen.
cOK button
Access to the selected item. d
Up button
Increases the temperature setting,
parameter or moves up.
e
Down button
Decreases the temperature setting,
parameter or moves down.
fPower button
Turns the water heater on or off.

10 Operating the Boiler
2. Press the OK button ( ) to select the space heating
temperature ( ). The highlighted section will flash.
3. Press the Up button ( ) or the Down button ( ) until the
desired temperature appears on the display. You can adjust
the temperature while the display is flashing. Once the
display stops flashing, the temperature setting is stored.
Note ●Take note of the original heating temperature in
case you want to restore it to the default.
●The default central heating supply water
temperature range is 40°C (Absolute MIN) to 90°C
(Absolute MAX).
●The default central heating return water
temperature range is 30°C (Absolute MIN) to 65°C
(Absolute MAX).
●The central heating temperature cannot be
adjusted when the Outdoor Reset Control is used.
●The central heating temperature cannot be
adjusted, when the Heat Demand function is set to
OpenTherm.
3.2.2 Adjusting the DHW Temperature
WARNING
Before adjusting the water temperature, carefully read “To
prevent burns:” on page 4. Water above 52°C can cause
instant scalding or severe burns.
To adjust the water temperature:
1. Make sure that all hot water taps are closed, and ensure that
the internal circulator and any external circulating pumps
are off.
3.1 Turning the Boiler On or Off
To turn the boiler on or off, press the Power button ( ).
When the power is turned on for the first time, you must
complete the start-up wizard. The temperature will appear on
the front panel display after the power is turned on.
3.2 Adjusting the Temperature
3.2.1 Adjusting the Central Heating Temperature
To adjust the central heating temperature:
1. In normal operation mode, press the Down button ( )
The central heating temperature ( ) is highlighted on the
screen.
3. Operating the Boiler

Operating the Boiler 11
3.3 Viewing Basic Information
To view information about the boiler, press the Menu button
(), and then select “2. Status Information”.
Press the Up button ( ) or the Down button ( ) to switch
between the information items. Press the OK button ( ) to
select an item and view the information.
Press the Back button ( ) to exit information view mode.
Item Description
1. Operation State Current Operation State
2. Heat Capacity Heat capacity (%)
3. CH Set Temp Central heating set temperature
(°C)
4. DHW Set Temp DHW set temperature (°C)
5. Supply Temp Heating supply temperature
(°C)
6. Return Temp Boiler return temperature (°C)
7. Outdoor Temp Outdoor temperature (°C)
8. Inlet Temp Inlet temperature (°C)
9. DHW Temp DHW temperature (°C)
10. Water Flow
Water flow rate (LPM)
If the rate is 0, “Calculation” will
be displayed.
11. Water Press Water pressure (bar)
12. Flame Value
Flame detector AD value
●Flame On: 8bit AD values
equal to or lower than 70
●Flame Off: 8bit AD values
equal to or higher than 175
13. Fan Target RPM Fan target speed (RPM)
2. In normal operation mode, press the Up button ( ) The
DHW temperature ( ) is highlighted on the screen.
3. Press the OK button ( ) to select the DHW temperature
temperature ( ). The highlighted section will flash.
4. Press the Up button ( ) or the Down button ( ) until the
desired temperature appears on the display. You can adjust
the temperature while the display is flashing. Once the
display stops flashing, the temperature setting is stored.
Note ●Take note of the original water temperature in case
you want to restore it to the default.
●The default DHW temperature range is 30°C to
65°C.
●The boiler will retain your settings during a power
outage.
●The DHW temperature cannot be adjusted, when
the Heat Demand function is set to OpenTherm.

12 Operating the Boiler
Item Description
14. Fan Current RPM Fan speed (RPM)
15. Fan Target APS Fan target speed (APS)
16. Fan Current APS Fan speed (APS)
17. Exhaust Temp Exhaust temperature (°C)
18. OTC ON/OFF OTC status (Enabled/Disable)
19. K-Factor Set Value K-Factor set value
20. Model Model type
21. Type Boiler type
22. Gas Fuel type (NG/LPG)
23. Main F/W ver Main firmware version
24. Panel F/W Ver Controller panel firmware
version
Note The fan moter controls the APS, so the fan target
speed (Fan Target RPM) is only for your reference.
3.4 Resetting the Boiler
If an error message appears, you can try resetting the boiler to
resolve the problem. To reset the boiler, press the Back button
().
If resetting the boiler does not solve the problem, refer to the
Troubleshooting section of this manual or contact a Technical
Assistance Service.

Troubleshooting 13
4.1 Solving Basic Problems
If you experience a problem with the boiler, refer to the
following chart for possible remedies. Error codes that appear on
the front panel display are explained in the following section.
For minor problems, resetting the boiler may resolve the issue.
To reset the boiler, press the Back button ( ) on the front panel.
4. Troubleshooting
If resetting the boiler and attempting the remedies suggested below do not resolve the problem, contact Navien Technical Assistance
Service (TAS) or a Gas Safe Registered Engineer.
Problem Possible Cause(s) What to do
No water comes out when the hot
water tap is opened.
●Is the return adapter filter clean?
●Is an error code displayed on the front
panel?
●Is the boiler frozen?
●Ensure that the shut–off valves on the hot
and cold pipes are open.
●If an error code is displayed, refer to
“4.2 Understanding Error Codes” on
page 14.
The water from the hot water tap is
cold or turns cold and stays cold.
●Is the hot water tap open wide enough
draw at least 1.9litres of water per minute
(LPM) through the boiler?
●Is an error code displayed on the front
panel?
If an error code is displayed, refer to
“4.2 Understanding Error Codes” on
page 14.
The water from the hot water tap is
not hot enough. Is the set temperature too low?
●Check the boiler’s temperature setting.
Refer to “3.2 Adjusting the Temperature” on
page 10.
●Check for cross plumbing between the
cold and hot water lines.
The water from the hot water tap is
too hot. Is the set temperature set too high?
Check the boiler’s temperature setting.
See “3.2 Adjusting the Temperature” on
page 10.
Central heating side malfunction
Is the setting temperature too low?
Check the boiler’s temperature setting.
See “3.2 Adjusting the Temperature” on
page 10.
Is there power to the system, or is the system
in standby?
Make sure the power is on, and plugged
into the outlet with the correct voltage.
Press the Power button and raise the setting
temperature. Make sure the boiler is turned
on.
Is the system running for domestic hot water
(DHW)?
When the unit is heating for DHW, the
heating side does not work.
Is the filter on the heating side restricted? Clean out filters that belong to the heating
side.

14 Troubleshooting
4.2 Understanding Error Codes
When an error code appears on the front panel, refer to the following chart for a definition and possible remedy for the situation.
Item Error Code Description Reset
Combustion
E001 Overheating of heat exchanger Manual
E003 Ignition failure Manual
E004 False flame detection Auto
E012 Flame loss Manual
E016 Heat exchanger overheat Manual
E030 Abnormal exhaust temperature Manual
E046 Abnormal operation: Heat exchanger overheating sensor Auto
E047 Abnormal operation: Exhaust thermostat Manual/Auto
E060 Abnormal operation: Dual venturi limit switch Alarm
Air Circulation
E109 Abnormal operation: Fan Manual
E110 Exhaust blockage (Condensate blockage) Manual
E127 Abnormal operation: APS Auto/Manual
Central Heating
Circulation
E205 Heating supply thermistor open or short circuit Auto
E218 Heating return thermistor open or short circuit Alarm
Water Supply
E302 Low water pressure Auto
E352 High water pressure Auto
E353 Abnormal operation: Water pressure sensor Auto
DHW Circulation
E407 DHW Outlet thermistor Open or Short Circuit Alarm
E421 DHW Inlet thermistor Open or Short Circuit Auto
Controller (PCB)
E515 Abnormal operation: Relay feedback (PCB) Manual
E517 Abnormal operation: DIP switch setting (PCB) Manual
E594 Abnormal operation: EEPROM (PCB) Alarm/Manual
Controller (MCU) E615 Abnormal operation: Input and memory (MCU) Manual
Installation
E740 Abnormal operation: Outdoor temperature sensor Auto
E782 Abnormal operation: Main panel communication Auto
E783 Abnormal operation: OpenTherm remote control Auto
E787 Abnormal operation: Reset device Manual/Power Reset
E788 Abnormal operation: Gas type settings Manual
If the error code is not cleared by resetting the boiler functioning (see “3.4 Resetting the Boiler”) or if it occurs repeatedly, call the nearest
official Technical Assistance Service (TAS), indicating the number of the error code appearing on the front panel.

Warranty 15
Annual service
For Navien warranty to be valid an annual service must be
carried out by a suitably qualified and Gas safe registered
installer every year after installation. The cost of this annual
service is not included in the guarantee.
Your Warranty Conditions
Navien undertakes to rectify any manufacturing defect that
occurs within 5 years of the installation date. Please go to our
website to see any additional years on the warranty.
For Navien warranty to be valid an annual service must be
carried out by a suitably qualified and Gas Safe registered
installer every year after installation.
1. Navien Warranty registration is simple. Just register the
boiler on the Navien Installers Warranty App within 30 days
of installation. The details of installation will be then be
automatically registered within Navien Service Management
System. Alternatively, please email a photo of your
completed benchmark form to [email protected].
2. The completed Benchmark Checklist will be required in the
event of any warranty work and may be required by the
local Building Control Inspector.
3. The cost of this annual service is not included in the
Warranty.
4. The start-up and annual service are to be carried out by a
suitably qualified and Gas Safe registered installer.
5. Navien Warranty will be null and void in the following cases:
●If the annual service by a suitably qualified and Gas Safe
registered installer has not been carried out.
●If the boiler has not been installed in accordance with the
applicable laws and regulations for this type of appliance.
●If the boiler has not been started up immediately after its
installation, by a suitably qualified and Gas Safe registered
installer.
6. Navien Smart Plus wireless thermostat comes with 2 year
warranty.
Navien Smart Plus wireless thermostat has a standard 2 year
manufacturer’s warranty if a suitably qualified engineer has
installed the system in accordance with Navien instructions.
Failures due to misuses or incorrect installation, use of non
suitable power or fuel, supply with water with physical
or chemical properties causing incrustation or corrosion,
incorrect handling of the appliance and, in general, for any
reason beyond Navien’s control, are excluded from this
guarantee. This warranty does not affect the consumer’s
rights as stipulated by law.
7. If your Navien boiler develops a fault your first action should
be contact your installer, as his professional assessment
is needed under the terms of Navien Warranty. If you are
unable to contact your installer, please phone Navien
Service: 0844 332 2323 or visit Navien website: www.navien.
co.uk.
Suitable Use
The NCB700 boiler is designed with all the necessary safety
systems. Unsuitable use of the appliance for a purpose it was not
designed for entails risk of damage to the boiler or property, and
even of injury to the user and other persons.
The NCB700 boiler is designed to generate heat for domestic
hot water and to be connected to central heating systems. Any
use other than the above will be considered unsuitable use of
the boiler. In such cases the manufacturer/supplier shall not
be liable for any damage caused, and the user will be liable for
the damage. Correct use of the boiler includes reading the user
and installation instructions and all applicable documents, and
complying with the maintenance and inspection conditions.
Everyday Care
Clean the outside of the boiler with a damp cloth with a little
detergent. Do not use abrasive products to clean the boiler.
Waste Recycling and Disposal
Observe the applicable national regulations and standards
concerning waste disposal.
The boiler
Neither the wall-mounted boiler or its accessories are to be
disposed of with the domestic waste. Ensure the appliance and
its accessories, where applicable, are suitably disposed of.
Packaging
The transport packaging will be disposed of by the specialist
technician who made the installation.
Warranty

16 ErP Information
Product Fiche (EU regulation No 811/2013)
KD Navien Unit NCB700-24L NCB700-28L NCB700-34L NCB700-40L
Central heating : temperature application Medium Medium Medium Medium
Water heating : the declared load profile XL XL XL XL
Seasonal central heating energy efficiency
class A A A A
Water heating energy efficiency class A A A A
Rated heat output kW 20 23 28 33
Central heating : annual energy consumption GJ 37 43 52 57
Water heating : annual electricity consumption kWh 66 65 45 46
Water heating : annual fuel consumption GJ 17 17 17 17
Seasonal central heating energy efficiency %92 93 93 93
Water heating energy efficiency %84 84 85 85
Sound power level dB 50 52 54 52
Specific precautions Read the user’s information and installation manual
before the application is assembled, installed or maintained.
ErP Information