Vaillant ecoTEC plus 824

Questions and Answers

T
Tricia ButlerSep 3, 2025
What to do if my Vaillant ecoTEC plus 824 Boiler appliance does not start and ignition fails?
- R
  Rachel WilliamsSep 3, 2025
  If your Vaillant Boiler fails to start and ignition attempts fail, there may be faults in the gas supply, such as a defective gas meter or gas pressure detector, air in the gas, gas flow pressure too low, or a disengaged fire protection tap. There may be faults in the gas valve, wrong gas setting, defective igniter (ignition transformer, ignition cable, ignition plug), stopped ionization current (cable, electrode), faulty earthing in the appliance or defective electronics. Inspect the gas supply and ignition components for faults.
K
Kyle SmithSep 8, 2025
Why is the safety temperature limiter by NTC activated in my Vaillant Boiler?
- D
  Douglas GonzalezSep 8, 2025
  The safety temperature limiter by NTC might be activated because the Flow-NTC is not correctly thermal-connected or is defective, causing the appliance not to shut down. Check the thermal connection of the Flow-NTC and replace it if defective.
M
Margaret HoustonAug 30, 2025
What does it mean if the flow sensor reports a constant value in my Vaillant Boiler?
- K
  Karen GonzalezAug 31, 2025
  If the flow sensor reports a constant value in your Vaillant Boiler, it indicates that the flow sensor is defective. Replace the flow sensor.
J
John JonesAug 26, 2025
Why does the flame go off during operation in my Vaillant ecoTEC plus 824 Boiler?
- T
  Taylor ZunigaAug 26, 2025
  If the flame goes off during operation and subsequent ignition attempts fail in your Vaillant Boiler, it could be due to a temporarily stopped gas supply, spark failure in the ignition transformer, or faulty earthing of the appliance. Check gas supply and ignition system for faults.
W
Whitney PorterAug 26, 2025
What causes rapid temperature rise in my Vaillant Boiler?
- A
  Austin StewartAug 27, 2025
  A rapid temperature rise in your Vaillant Boiler, indicating a water shortage, can be caused by a blocked pump, insufficient pump output, air in the appliance, low plant pressure, or interchanged flow and return NTCs. Inspect system for air and correct pump issues.
K
Kevin ClarkSep 18, 2025
What does it mean if my Vaillant Boiler water pressure sensor signal is out of range (too high)?
- M
  Michael RivasSep 18, 2025
  If the water pressure sensor signal is out of range (too high), the cable to the water pressure sensor has a short-circuit at 5 V / 24 V, or there is an internal fault in the water pressure sensor. Inspect and repair the cable and replace the water pressure sensor.
C
Connor YoungSep 23, 2025
What to do if the gas supply to my Vaillant ecoTEC plus 824 Boiler is off?
- D
  Deborah EvansSep 23, 2025
  If the gas supply to your Vaillant Boiler is off or not correctly purged, check that the gas supply to the boiler is on, that it has been correctly purged, and that an inlet pressure of 20 mbar is available at the gas valve.
L
Lisa ArmstrongSep 12, 2025
What does EEPROM error mean in my Vaillant ecoTEC plus 824?
- D
  Donald PattonSep 13, 2025
  An EEPROM error indicates that the electronics are defective. Replace the defective electronics.
P
Paula ClarkSep 4, 2025
What to do if the flame goes off during operation of my Vaillant ecoTEC plus 824 Boiler?
- L
  Luis MeyerSep 4, 2025
  If the flame goes off during operation and subsequent ignition attempts fail, it could be due to a temporarily stopped gas supply or faulty earthing of the appliance. Check the gas supply and earthing connections.
C
Curtis BurkeSep 23, 2025
What to do if the external electricity supply to my Vaillant ecoTEC plus 824 Boiler is not on?
- J
  Joseph HallSep 23, 2025
  If the external electricity supply to your Vaillant Boiler is off, ensure that the external electricity supply to the boiler is on and that a supply of 230 V~ is present between boiler terminals 'L' and 'N'. Also, ensure that the electrical supply is turned on.

Summary

1 Introduction

1.1 Notes on the documentation

Information to help users throughout the documentation. Covers applicable documents and retention.

1.2 Introduction

Details on boiler installation and servicing by competent persons, and CORGI registration.

1.3 General Notes

Describes boiler design for sealed central heating systems, mounting, and flue options.

1.4 CE marking

Explains the CE marking compliance with EU directives for gas appliances and EMC.

1.5 Gas council numbers

Lists gas council numbers for various Vaillant ecoTEC appliance models.

2 Boiler specifications

2.1 Technical data

Provides detailed technical specifications for ecoTEC boilers including outputs, dimensions, and electrical data.

2.2 Dimensions

Illustrates the physical dimensions of the boilers with a legend for connections and components.

2.4 Installation

Diagrams showing function elements of combination and system boilers for installation.

2.5 Type plate

Information on the location of the Vaillant ecoTEC type plate attached at the factory.

3 General requirements

3.1 Preliminary remarks for room sealed appliances

Guidance on installing Vaillant boilers with approved flue systems and installation instructions.

3.2 Related documents

Lists relevant regulations, British Standards, and publications for boiler installation.

3.3 Contents included with delivery

Details the components included in the Vaillant ecoTEC package unit for system and combination boilers.

3.4 Installation site

Specifies requirements for the installation location, including space for servicing and air circulation.

3.5 Gas supply

Details requirements for gas supply, meter connection, pipework, and leak testing.

3.6 Flue pipe

Emphasizes the use of genuine Vaillant flue pipes and describes standard and optional flue systems.

3.7 Flue termination

Provides details on flue termination positions and clearances according to BS 5440.

3.8 Air supply

Discusses air supply requirements and ventilation for cupboard or compartment installations.

3.9 Electrical supply

Outlines requirements for the 230V electricity supply, connection methods, and earthing.

3.10 Guide to system requirements

Covers water circulation systems, filling, pressure relief, and expansion vessels.

3.11 Pump specifications

Details the circulating pump specifications and by-pass valve adjustments.

3.12 Condensate trap

Describes the siphonic condensate trap or normal condensing water trap.

4 Boiler installation sequence

4.1 Transporting the appliance

Provides detailed manual handling recommendations for lifting and moving the boiler.

4.2 Required minimum distances;assembly clearances

Specifies minimum clearances around the boiler for installation and servicing.

4.3 Flue exit

Instructions for marking and preparing the flue exit hole based on flue system type.

4.4 Fitting the boiler hanging bracket

Details on fixing the hanging bracket securely to the wall for boiler mounting.

4.5 Installing the flue system

Guidance to install the flue system referring to separate air/flue duct installation instructions.

4.6 Fitting the boiler

Instructions for lifting and engaging the boiler onto the hanging bracket.

4.7 Removing the front case

Step-by-step guide on how to remove the front casing of the boiler.

4.8 General instructions for heating system

Cautionary advice on cleansing the heating system before connecting the appliance.

4.9 Gas connection

Details on making the gas connection, including safety, pipework, and leak checks.

4.10 Cold water mains inlet and hot water outlet

Instructions for connecting cold water and hot water pipes for combination boilers.

4.11 Condensate drain pipe

Describes the condensate trap and connection to the discharge pipework.

4.12 Heating connection

Instructions for connecting heating flow and return pipes and pressure relief valve.

4.13 Connecting the flue system to the boiler

Reference to separate air/flue duct installation instructions for connecting the flue system.

4.14 Electrical connection

Covers general electrical requirements, main supply connection, and wiring diagrams.

4.15 Controls

Details Vaillant controls, accessories, and connection details for external electrical controls.

4.16 Thermostatic radiator valves

Discusses the use of thermostatic radiator valves with the boiler's automatic by-pass.

4.17 Frost protection

Explains the integral frost thermostat and the need for additional protection measures.

4.18 Circulating pump

Information on the built-in circulating pump and its automatic overrun period.

4.19 Anticycling ‘economiser’ control

Describes the anticycling control to prevent energy-wasteful short cycling of the boiler.

4.20 Automatic pump spin control (APS)

Explains the APS feature that spins the pump to prevent seizure during periods of non-operation.

5 Commissioning Part I

5.1 Preliminary electrical checks

Checks for short circuit, earth continuity, resistance to earth, and correct polarity.

5.2 Gas supply

Inspection, leak check, and purging of the gas installation according to regulations.

5.3 Cold water supply

Procedure for filling and purging the hot water circuit for combination boilers.

5.4 Filling and bleeding the heating system

Detailed steps for filling and bleeding the heating system, including using test programs.

5.5 Initial system flush (“cold”)

Instructions for flushing the heating system to remove installation residues.

5.6 Filling the condensate siphon

Guidance on filling the condensate siphon with water to prevent fume escape.

5.7 Adjusting the pumping capacity

Information on adjusting the two-stage pump capacity for ecoTEC plus boilers.

5.8 Adjusting the by-pass

Details on adjusting the appliance's by-pass valve for pressure control.

5.9 Checking the gas supply

Procedure for checking gas inlet working pressure and gas rate.

5.10 Refitting the case

Instructions for refitting the front casing and securing clips after commissioning.

5.11 Adjusting the central heating output (range rating)

How to adjust the boiler's central heating output range rating.

5.12 Gas changeover

Information on converting the appliance between natural gas and LPG modes.

6 Functional checks (commissioning part II)

6.1 Functional checks

Procedure for performing functional checks on the appliance after installation.

6.2 Handing over to the user

Guidance on instructing the user about boiler operation, controls, and maintenance.

7 Inspection and maintenance

7.1 Initial inspection

Recommendations for regular inspection and servicing of the boiler for safe operation.

7.2 Servicing the burner module

Detailed steps for removing, cleaning, and refitting the burner module and its components.

7.3 Cleaning the condensate siphon

Instructions for cleaning the condensate siphon to prevent fume escape.

7.4 Checking the expansion vessel

Procedure for checking the expansion vessel charge pressure every three years.

7.5 Recommissioning the boiler

Steps for recommissioning the boiler after maintenance tasks are completed.

7.6 Test operation

Checks to perform after any maintenance task, including gas/water leaks and burner operation.

8 Troubleshooting

8.1 Logical fault finding procedure

A systematic approach to diagnosing and resolving boiler faults before using fault codes.

8.4 Test programs

Details on triggering special functions and test programs via the appliance controls.

8.5 Resetting parameter to factory settings

Instructions on how to reset individual or all parameters to factory default settings.

9 Parts replacement

9.1 Safety instructions

Crucial safety instructions to follow before and during component replacement.

9.2 Replacing burner

Step-by-step guide for replacing the burner module, including safety precautions.

9.3 Replacing fan or gas valve

Procedure for replacing the fan or gas valve, ensuring correct component positioning.

9.4 Replacing expansion vessel

Instructions for replacing the expansion vessel, including pressure checks.

9.5 Replacing primary heat exchanger

Guidance on replacing the primary heat exchanger, including safety and disconnection steps.

9.6 Replacing electronics and display

Steps for replacing electronic components and setting the appliance variant number.

9.7 Check CO2 content and if necessary set (air ratio adjustment)

Procedure for checking and adjusting CO2 content for optimal combustion.

10 Recycling and disposal

11 Vaillant service

12 Appendix

EC declaration of conformity

Document confirming the appliance's compliance with relevant EU directives.

PART 1 CONCENTRIC 60;100 Flue Installation

Requirements

Regulations and standards to be observed for flue installation.

Planning the air;flue duct layout

Details on alternative termination accessories and planning flue duct layout.

Installation of the sliding sleeve

Instructions for installing the sliding sleeve to allow flue fitting flexibility.

Installation of the horizontal air;flue duct

Steps for installing horizontal air/flue duct systems, including top and side outlets.

Installation of the black terminal kit

Guidance on assembling and installing the black terminal kit for horizontal air/flue ducts.

Installation of the variable termination kit

Instructions for installing the variable termination kit, including flue terminal clearances.

Installation of the vertical air;flue duct

Procedure for installing vertical air/flue duct systems, including pitched and flat roof installations.

Fitting air;flue duct extensions

Instructions on how to add extensions and install elbows for air/flue ducts.

PART 2 CONCENTRIC 80;125 Flue Installation

Requirements

Regulations and standards to be observed for flue installation.

Planning the air;flue duct layout

Details on alternative termination accessories and planning flue duct layout for 80/125 systems.

Changing the appliance connection piece

Instructions for changing the appliance connection piece for different air/flue duct systems.

Installation of the sliding sleeve

Guidance for installing the sliding sleeve for 80/125 air/flue duct systems.

Installation of the horizontal air;flue duct

Steps for installing horizontal air/flue duct systems with extensions for 80/125 diameter.

Installation of the vertical air;flue duct

Procedure for installing vertical air/flue duct systems for 80/125 diameter.

Fitting air;flue duct extensions

Instructions on adding extensions and installing elbows for 80/125 air/flue ducts.

Vaillant ecoTEC plus 824 Specifications

General

Model	ecoTEC plus 824
Category	Boiler
Type	Combination Boiler
Output	24 kW
Dimensions (H x W x D)	720 x 440 x 338 mm
Efficiency	89.3%
Energy Efficiency Class	A
Mounting	Wall-mounted
ERP Rating	A
DHW Output (kW)	24 kW
Maximum Working Pressure	3 bar
Weight	34 kg
Fuel	Natural Gas
Warranty	5 years