Vaillant 831 Ecotec Plus Combi Boiler User Manual

June 9, 2024
Vaillant

Vaillant 831 Ecotec Plus Combi Boiler User Manual

Notes on these instructions

To ensure clarity of information in instructions a new European standard of advice and symbols is being introduced. To ensure compliance with this new standard the following details are included.
The following information is intended to help you throughout the boiler’s entire instruction pack.
We assume no liability for any damage caused by the non-observance of these instructions.
Other instructions supplied with this appliance For the end-user
Short operating instructions (ecoTEC plus only) no. 838404
The warranty card with return envelope no. 802922

For the installer/service engineer:
Instructions for installation and servicing no. 839592
Flue installation instructions no. 835296

The instructions for any accessories and controllers used also apply.
The Benchmark gas boiler commissioning checklist (in the installation manual) should be completed by the installer and/or the commissioning engineer.
If, after reading these instructions, you have any questions on the operation of the boiler, please contact either your installer or Vaillant Technical Department.

Storage of the documents
Please store this user manual and all related documents so that they are available whenever they are required. If you move please pass on the documents to the buyer.

Symbols used in this manual
Please observe the safety instructions in this operating manual for the operation of the appliance.

  • Danger
    The immediate risk of serious injury or death.

  • Caution
    Potentially dangerous situations for the product and environment.

  • Note
    Useful information and instructions.

CE marking
The purpose of CE marking is to certify that the boiler complies with the requirements of the directives covering gasfired appliances (Council directive 90/396/EEC) and electromagnetic compatibility (Council directive 89/336/EEC).
These appliances also comply with the requirements of the directive on operating efficiency (Council directive 92/42/EEC).

Data badge
The type plate of the Vaillant ecoTEC is attached at the factory to the bottom of the appliance.

Safety

Setup and adjustments
Installation and adjustment of the boiler as well as service, maintenance and repair of the boiler may only be carried out by a competent person in accordance with the Gas Safety (Installation and Use) Regulations 1998. (In the U.K. “CORGI”. Registered installers undertake the work to a safe and satisfactory standard). If the boiler is installed in a compartment do not obstruct any purpose-provided ventilation openings, and do not use the compartment for storage purposes.

What to do in an emergency

Danger
The smell of gas. Risk of poisoning and explosion due to a malfunction

If you smell gas or suspect a gas leak:

  • Do not switch lights on or off.
  • Do not use any other electrical switches.
  • Do not use a telephone in the hazardous area.
  • Do not use naked flames, such as matches or cigarette lighters.
  • Do not smoke.
  • Turn off the gas supply at the gas meter.
  • Open the windows and doors.
  • Warn other residents.
  • Get out of the house.
  • Consult your gas supplier, service agent or another competent person.

Safety instructions
Always observe the following safety instructions and regulations.

Danger
Inflammable mixtures of gas and air may explode.
Do not use or store explosive or easily flammable substances such as petrol or paint in the same room as the appliance.

Danger
Risk of poisoning and explosion due to a malfunction.
Never put the safety devices out of operation or tamper with them so as to impair their function.

Modifications in and around the boiler
No modifications may be made to the following items:

  • The boiler
  • The gas, water and electrical supply
  • The flue system
  • The safety valve for the heating water
  • Any structural changes around the appliance could affect the operational safety of the boiler.

Caution
Inappropriate modifications can cause damage. Never tamper with the boiler or other parts of the system.
Never attempt to perform maintenance or repairs yourself.

  • Do not damage or remove seals on components. Only authorized engineers or our customer service may remove sealed components.

Danger
Risk of scalding.
The water coming out of the tap can be very hot (ecoTEC combination boiler only).

Caution
Risk of damage.
Do not use sprays, solvents, chlorinated cleaning agents, paint, adhesives or similar substances in the vicinity of the appliance. These substances can cause corrosion, including in the flue system.

Installation and setting
Important:
The appliance must be installed and serviced by a Competent Person as stated in the Gas Safety (Installation and Use) Regulations 1998. In IE, the installation must be in accordance with the current edition of I.S.813 ‘Domestic Gas Installations, the current Building Regulations and reference
should be made to the current ETCI rules for electrical installation.

Caution
The appliance may only be operated with its case properly and permanently closed. Otherwise, in unfavorable conditions, material damage or even injury or death can result.

Filling pressure of the heating system
Regularly check the filling pressure of the heating system (see 4.3.2).

Leaks (ecoTEC combination boiler only)
If there is a leak in the water pipes between the appli-ance and the taps, immediately turn off the cold water service valve and have your engineer repair the leak.

Frost protection
Your boiler is equipped with a frost protection function: If the heating water temperature drops below 5 °C when the main switch is ON, then the boiler goes into operation and heats the boiler circuit to approx. 30 °C.

Note
It cannot be guaranteed that water will circulate throughout the entire heating system.

If the boiler is not operated for several hours during very cold weather there is therefore the possibility of the system freezing.
Please ensure that if you are absent during a period of frost the central heating remains in operation and all rooms are kept above freezing point.
It must be remembered, however, that the boiler will be automatically switched off by the built-in monitoring devices if certain faults occur, e.g. interruption in the gas or electricity supply or faults in the flue gas system. To overcome this possibility you can drain both the central heating system and boiler.

Note
Frost protection and monitoring devices can only function when the main switch of the unit is set to the “I” position and the boiler is con-nected to the electrical supply.

Instructions on operation

Factory guarantee
Two 2 year guarantees for ecoTEC plus appliances
Vaillant undertakes to rectify any manufacturing defect that occurs within twenty-four months of the installation date.
For the 2nd year of the guarantee to be valid an annual service must be carried out by a CORGI-registered installer one year after installation.
The cost of this annual service is not included in the guarantee.

One-year guarantee for ecoTEC pro appliances
Vaillant undertakes to rectify any manufacturing defect that occurs within twelve months of the installation date.

Registering with us
Registration is simple. Just complete the Guarantee Registration Card and return to Vaillant within 30 days of installation. Your details will then be automatically registered within the Vaillant scheme.

Immediate help
If your Vaillant boiler develops a fault your first action should be to contact your installer, as his professional assessment is needed under the terms of our Guarantee. If you are unable to contact your installer, phone Vaillant Service Solutions: 0870 6060 777

Intended use
Vaillant ecoTEC boilers are state-of-the-art appliances that have been constructed in accordance with recognized safety regulations. Nevertheless, there is a risk of injury or death to the user or others and damage to the appliance or other property in the event of misuse or use for which the appliance is not intended.
The appliances are designed to generate heat for connected hot water central heating systems. Any other use is considered to use other than intended. The manufacturer/supplier is not liable for any resulting damage. The user alone bears the risk.
Intended use includes the observance of the operating and installation manual and all other applicable docu-ments, as well as adherence to the maintenance and inspection conditions.

Care
Clean the exterior your appliance with a damp cloth and a little soap.

Recycling and disposal
Both your Vaillant ecoTEC boiler and its packaging consist mainly of recyclable raw materials.

The appliance
Do not dispose of your Vaillant ecoTEC boiler or any of its accessories with household waste. Make sure the old appliance and any existing accessories are disposed of properly.

Packaging
Please leave the disposal of the transport packaging to the expert company which installed the appliance.

Operation

Overview of controls on ecoTEC plus

For access to the controls open the front flap by pulling at the center of the case strip.

  1. Display indicating the current heating flow temperature, the pressure in the heating system, the operat-ing mode or additional information
  2. The “i” information button
  3. Built-in control/timer (if fitted)
  4. Pressure gauge displaying the pressure in the heating system
  5. Main ON/OFF control
  6. “+” button for moving forward in the display
  7. “-” button for moving back in the display or for displaying the pressure in the heating system
  8. The “Reset” button
  9. Maximum radiator temperature control
  10. Maximum hot water temperature control and warm start ON/OFF control (ecoTEC plus combination boilers only)

The advanced multifunctional display system

The ecoTEC plus appliance is fitted with a digital information and analysis system. This system provides information on the operating status of your appliance. During normal operation, display (1) shows the current heating flow temperature (in this example 45 °C). In the event of a fault, an error code appears instead of the temperature.

The display also gives the following information:
Indication of the current heating system flow temperature or water pressure in the heating system or display of a status or error code
Fan speed malfunction

As long as this symbol appears in the display, a heating flow temperature and hot water outlet temperature is set by the vrnetDIALOG accessory, which means the appliance uses temperatures other than those set using the controls (9) and (10).

This condition can only be ended:

  • using vrnetDIALOG or

  • by a change in temperature at controllers (9) or (10) of more than ±5 K.
    This condition cannot be ended:

  • with the “Reset” button (8) or

  • by turning the appliance off or on.
    Heating mode active

  • Illuminated: Heating mode

  • Flashing: Anti-cycling mode active

  • Hot water supply active  (ecoTEC plus combination boilers only)

  • Illuminated: Hot water demand (ecoTEC system boilers only)

  • Illuminated: Heating of an indirect hot water cylinder turned on

  • Flashing: Heating demand from the hot water cylinder, burner on

  • Warmstart system active (ecoTEC plus combination boilers only)

  • Illuminated: Warm start turned on

  • Flashing: Warm start demand, burner on

  • The internal pump is running

  • The gas valve is activated

  • Flame with cross:
    The boiler is at lockout and will display the fault code

  • Flame without cross:
    Normal burner operation

Overview of controls on ecoTEC pro

  1. Display indicating the current heating flow temperature, the pressure in the heating system or additional information
  2. Indicator lights to display the current operating mode 3 The “i” information button
  3. Built-in control/timer (if fitted)
  4. Pressure gauge displaying the pressure in the heating system
  5. Main ON/OFF control
  6. “+” button for moving forward in the display
  7. “-” button for moving back in the display or for displaying the pressure in the heating system
  8. The “Reset” button
  9. Instructions for use ecoTEC
  10. Maximum radiator temperature control
  11. Maximum hot water temperature control and warm start ON/OFF

Multifunctional display system
ecoTEC pro boiler has a multifunction display (1). When the main ON/OFF control is in the “ON” position the display will normally show the system CH flow temperature of water in the boiler circuit (45 °C in the example), which confirms that the boiler is functioning correctly.

  1. Display indicating flow temperature or the system
    pressure or the relevant fault code.

  2. Green warm start indicator Illuminated = Warmstart switched ON
    Not illuminated = Warmstart is switched OFF and there is no demand for hot water
    Flashing = There is either a demand for hot water or warm start

  3. Yellow indicator
    Illuminated = Main burner ignited 4 Red indicator
    Illuminated = Boiler is at lockout and will display fault code

As long as this symbol appears in the display, a heating flow temperature and hot water outlet temperature is set by the vrnetDIALOG accessory, which means the appliance uses temperatures other than those set using the controls (10) and (11).
This condition can only be ended:

  • using vrnetDIALOG or
  • by a change in temperature at controllers (10) or (11) of more than ±5 K.

This condition cannot be ended:

  • with the “Reset” button (9) or
  • by turning the appliance off or on.
Initial checks before turning on

Opening the service valves

Note
If a bottom cover is fitted to the boiler the service valves are behind this cover.

  • Ensure that the service valves in the heating flow and return (4 and 1) and the gas service valve (3) are open. The flow, return and gas service valves are open when the screwdriver slot is in the same direction as the pipework.
  • On ecoTEC combination boilers only:
    Ensure the cold water service valve (2) is open. This can be checked by opening a hot water tap and ensuring water flows.
    Caution
    The pressure relief valve is provided for safety reasons and must not be interfered with.

Checking the system pressure

Check the water pressure of the system using the pressure gauge (1) before putting the boiler into oper-ation. For the heating system to operate properly, the indicator on the pressure gauge must be in the dark grey zone when the system is cold. This is a filling pressure between 1.0 and 2.0 bar. If the indicator is in the light grey area (below 0.8 bar), fill the system up with water before putting the boiler into operation.

Note
The ecoTEC appliance has a pressure gauge and a digital pressure display.
The pressure gauge allows you to quickly check whether the filling pressure is in the correct range, even when the appliance is switched off. When the appliance is in operation, you can see the exact pressure in the display. Activate the pressure display by pressing the “-” button (2). After 5 seconds the display returns to the flow temperature.

Note
Your appliance has a pressure sensor.
If the pressure falls below 0.6 bar the pressure flashes in the display.
If it falls below 0.3 bar the appliance switches off. The error message F.22 appears in the display. The system must be filled with water before you start up the appliance again.

Turning the boiler ON

Use the main ON/OFF control (1) to switch the appli-ance on.

  • I: “ON”
  • 0: “OFF”
    When you switch on the appliance, the current operating status appears in the display (2).
    To adjust the appliance according to your requirements, read sections 4.5 and 4.6, which describe the setting options for hot water supply and heating.

Caution
Risk of damage.
The boiler frost protection and monitoring sys-tems are only active when the main ON/OFF control of the appliance is in the “I” position and it is not disconnected from the main power supply.

Domestic hot water with ecoTEC combination boilers
The boiler must only be used when the heating system contains water (see 4.3.2).

Setting the water temperature

  • Switch on the appliance as described in section 4.4.
  • The domestic hot water temperature can be adjusted using the hot water temperature control (3).
  • Turn the control clockwise to increase the temperature and anti-clockwise to decrease the temperature. This corresponds to:
    • left limit approx. 35 °C
    • right limit max. 65 °C.

Note
This control adjusts the maximum domestic hot water temperature. If adjusting the control upwards appears to have no effect on the tem-perature, then the boiler is already operating at full output for the selected flow rate.

When you adjust the required temperature, the set value is shown in the display (2).
After five seconds the display returns to standard mode (the current heating flow temperature).

Caution
If you live in a hard water area please do not set the control knob (3) above the mid (12 o’clock) position to prevent excessive scale formation.

Switching the warm start function on and off
The warm start system of the ecoTEC combination boilers provides you with hot water at the required temperature immediately. To do this, the hot water heat exchanger of the ecoTEC is kept at a pre-selected temperature level and the boiler will therefore periodically operate to maintain this temperature.

ecoTEC plus:

  • Activate the warm start system by briefly turning the knob (1) all the way clockwise (position a).
    Then select the desired hot water outlet temperature again, e.g. setting b (refer to Section 4.5.1). The appliance
    automatically adapts the hot holding temperature to the set hot water temperature. The tempered water is directly available at the taps; the symbol flashes in the display.

  • Switch off the warm start system by briefly turning the knob (1) all the way anti-clockwise (position c). The symbol disappears. Then select the required hot water outlet temperature again, e.g. setting b.

ecoTEC pro:

  • Activate the warm star system by briefly turning the knob (1) all the way clockwise (position a). The green LED (2) lights up.
    Then select the required temperature, e.g. setting b, see 4.5.1.
    The water is kept at a constant temperature of 55 °C and is available immediately as you turn on a tap.

  • Switch off the warm start system by briefly turning the knob (1) all the way anti-clockwise (position c). The green LED (2) goes out. Then select the required hot water outlet temperature again, e.g. setting b.

Drawing hot water (ecoTEC combination boilers only) On opening a hot water tap (1) at a supply point (basin, shower, bath, etc) the ecoTEC combination boiler will automatically operate to deliver hot water.
On closing the tap the boiler switches OFF (or continues to operate for central heating if required).

Heating operation
The boiler must only be used when the heating system contains water (see 4.3.2).

Setting the maximum radiator temperature control

Set the maximum radiator temperature control to the desired setting using the control knob (1).
We recommend the following settings:

  • Left setting during spring and autumn,
  • Middle setting during mild winter,
  • Right setting during cold winter.

When you adjust the temperature, the set value is shown in the display (2). After five seconds the display returns to standard mode (the current heating flow temperature).
Normally you can adjust the knob (1) continuously up to a flow temperature of 75 °C. However, higher temperatures can be set on your appliance, have your engineer make adjustments so that you can operate the heating system at higher flow temperatures.

Switching off the heating (summer operation)
You can switch off the heating in summer without switching off the hot water supply.
Turn the knob (1) for setting the maximum radiator temperature all the way to the left.

Setting a room- or outside temperature controller

Set the room thermostat (1) and/or the thermostatic radiator valves (2) according to the instructions supplied with the control(s).

Note
Vaillant offers room thermostat/time control accessories which give accurate and economic room temperature control as well as improved comfort.

The boiler will now operate automatically to provide central heating for the conditions selected on the external controls (ecoTEC combination boilers will also provide domestic hot water on demand).
After the boiler stops operating the pump will continue to operate for a short period to fully disperse the heat from the boiler.

Note
The boiler incorporates an anti-cycling economizer control to prevent energy- wasteful ON and OFF operation of the boiler for short peri-ods when in central heating mode. When turning the room thermostat to a higher setting there may therefore be a short delay before the boiler operates.

Status displays The status displays provide information on the operating status of the appliance.

  • Press the “i” button (1) to activate the status displays. The display (2) then shows the current status code, for example, “S. 4” for burner operation. The table below explains the most important status codes.
    In switching phases, for example on starting up again after the flame was extinguished, the status message “S.” briefly appears.

  • Press the “i” button (1) again to switch the display back to normal mode.

Display Meaning
Displays during heating operation
S. 0 No heat required
S. 1 Pump running
S. 3 Ignition sequence (heating operation)
S. 4 Burner ignited
S. 6 Fan and pump overrun
S. 7 Pump overrun
S. 8 Anti-cycling mode (after heating operation)
S.30 Room thermostat 3/4 no heating demand
S.31 Summer mode active
S.34 Frost protection mode
Displays in hot water operation (ecoTEC combination

boilers only)
S.10| Hot water demand
S.14| Burner ignited
| Displays for hot holding operation (ecoTEC combination boilers only)
S.20| Hot holding request
S.24| Hot burner holding operation on
| Displays in cylinder charging mode (ecoTEC system boilers only)
S.20| Cylinder charging request
S.24| Cylinder charging burner on

Troubleshooting

In the unlikely event that a problem occurs with the operation of the ecoTEC boiler, the following points should be checked:

Boiler fails to operate:

  • Is the gas supply turned on (see 4.3.1)?

  • Is the water supply turned on (ecoTEC combination boilers only, see 4.3.1)?

  • Is there enough water in the heating system (see 4.3.2)?

  • Is the electrical supply switched ON?

  • Is the main ON/OFF control in the “ON” position  (switch position “I”, see 4.4)?

  • Is there an ignition problem (see 4.8.2)?
    Hot water operates but no central heating (ecoTEC combination boilers only)

  • Is the heating turned ON (see 4.6.1)?

  • Are all external heating controls ON (see 4.6.3)?

Caution
Inappropriate modifications can cause damage.
If your boiler still does not operate then please consult your installer or Vaillant Service Solutions (0870 6060 777).

Problems due to low system water pressure
The device switches to “Fault” if the water pressure in the heating system is too low. This malfunction is indicated by the fault code “F.22” (dry fire) or “F.23” or “F.24” (lack of water).
You can only start up the appliance again when the heating system is sufficiently filled with water.

Ignition problems If the burner fails to ignite after five attempts, the device does not start up and switches to “Fault”. This is indicated by the fault code “F.28” or “F.29” in the display. On ecoTEC plus appliances, the display also shows the flame symbol with a cross through it (1). On ecoTEC pro appliances, the red LED (2) also lights up. Automatic ignition can only take place after you manually reset the fault.
To reset the fault, press the reset button (3) and hold it down for one second.

Caution
If the boiler still shuts off after three attempts of resetting, please consult your installer or Vaillant Service Solutions.

Flue problems
The appliances are fitted with a fan. If the fan does not work properly, the appliance will switch itself off.
The display shows the symbols and the fault message “F.32”.

Note
If contacting Vaillant Service Solutions please remember to quote the fault code, as this will help to pinpoint the fault.

Turning off the boiler

Turn the main ON/OFF control (1) to the „0“ position.

Caution
The boiler frost protection and monitoring systems are only active when the main ON/OFF control of the appliance is in the “I” position and it is not disconnected from the main power supply.

Note

  • If the appliance is switched off for a long time (for example when you are on holiday) you should also turn off the gas supply, the cold water service valve and the electrical supply.
  • Do not turn the ecoTEC system boilers OFF if a hot water cylinder is also incorporated in the system unless there is no demand for domestic hot water.

Frost protection
The frost protection feature only protects the boiler. Any other parts of the system liable to frost damage should be protected accordingly.

Caution
The frost protection and monitoring systems are only active when the main ON/OFF control of the appliance is in the “I” position and it is not disconnected from the main power supply.

Frost protection function
The boiler has a frost protection function.
If the heating flow temperature falls below 5 °C with the main ON/OFF control turned on, the appliance starts up and heats the boiler to 30 °C.

Caution
Parts of the system may freeze.
The frost protection function cannot guarantee that water flows through the entire heating system.

Maintenance and customer service

Inspection and maintenance
Permanent operational readiness, reliability and a long service life require inspections and maintenance work to be regularly carried out by a heating engineer or Vaillant.For further details please contact Vaillant Service Solutions: (0870 6060777).

Danger
Risk of injury and damage due to improper handling
Never attempt to perform maintenance or repairs on the appliance yourself.
Have a specialist heating company do the work. We recommend signing a service agreement. The reliability of the appliance can be impaired, resulting in damage to property or personal injury if maintenance work is not carried out.
Regular servicing ensures maximum efficiency and economical operation of your gas wall heater.

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