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Exam revision materials for Plumbing Level 2&3 and ACS Gas Safety test

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HUB-001A-WAX Vado Thermostatic Cartridge


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Servicing Guide



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Gas Safety Inspection

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Vaillant ecoTec Plus 937 - Hot water pump 0020039793

Vaillant ecoTec Plus 937 - Hot water pump 0020039793 doesn't work

When this particular boiler does not produce any hot water but the heating is working the hot water pump might be faulty.

Replacement part number is 0020039793

< Go Back2019-06-02

Vaillant ecoTec Plus 637 F.75 Fault Pump replacement 0020025042

Vaillant ecoTec Plus 637 F.75 Fault

  • Boiler is not working and fault code F.75 is showing.
  • Check the power to the pump 240v when boiler deman is on
  • If there is power then open the pump vent screw (small amount of water will escape)
  • With a screwdriver check if the impeller is rotating
  • If its rotating try to stop it with the screwdriver
  • If its easy to stop then replae the pump

Pump replacement  part number is 0020025042

< Go Back2017-09-26

Vaillant ecoTec plus 831 - F.75 error message - faulty expansion vessel (181051)

Vaillant ecotec Plus 831 shows an error code F.75 after few minutes of trying to ignite

  • Check the pressure sensor and the pump. If they both are fine then look at the expansion vessel
  • Open a recharge nipple and press. If water is coming from the vessel then the expansion vessel is faulty and needs replacement.
  • The part numbers are: Vaillant Ecotec Expansion Vessel 181051 
< Go Back2017-05-06

Vaillant Turbomax Plus 837E F.28 Gas valve 114189 Original Sigma 845

Vaillant Turbomax Plus 837E displays an error code F.28

  • If PCB is fine and the spark electrodes are fine the adjust the gas valve ignition burner pressure and operating burner pressure according to the manufacturer's instructions
  • If the pressure adjustments don't last and change by themselves then replace a gas valve
  • Gas valve replacement part is 114189 Original Sigma 845
< Go Back2017-05-06

Vaillant EcoTec plus 637 F.32 Faulty fan 193593

Vaillant ecoTec plus 637 system boiler doesn't work with a fault code F.32

  • The boiler fan is faulty fan 193593 or a Printed Circuit Board (PCB) is faulty
  • To test take the electrical connection out of the fan and measure DC voltage across Red and Blue wires. The voltage should be 22VDC
  • If no voltage present replace the PCB
  • If voltage is present then replace the fan
< Go Back2017-04-09

Vaillant ecotec Plus 824 - Fault F.75 - Faulty expansion vessel (181051)

Vaillant ecotec Plus 824 looses pressure after using heaiting.

  • When you turn the heating on after the short period of time the pressure level goes up to red zone (3Bars)
  • High pressure forces a Pressure Relief Valve to open to release the excessive pressure from the system as the water expands when heated up (up to 4% at 100ºC)
  • An expansion vessel contains a rubber membrane which separates a pressurised air and central heating water.
  • Annual boiler service is required to check and re-pressurise the expansion vessel up to 1 bar (with a bicycle pump). Drain the boiler water before recharging.
  • If water starts leaking from the expansion's vessel nipple then it is faulty and needs replacement. Very often it needs replacement together with a Pressure Relief Valve
  • The part numbers are: Vaillant Ecotec Expansion Vessel 181051 & PRV 178985
< Go Back2017-03-05

Vaillant ecoTec plus 837 - Diverter valve 0020132682 leaking

Vaillant ecoTec plus 837 is constantly leaking water and loosing pressure

< Go Back2016-03-25

Vaillant ecoTec pro24 - fault F62 PCB 0020132764 or Gas valve replacement

Vaillant ecoTec pro24 combi boiler has an intermittent fault F.62 which stops hot water and heating to work

  • Fault F.62 indicated problem with a Gas Valve or PCB. 
  • Need to carry out the following test to identify:
    • To test the gas valve remove the electric plug from the gas valve and measure the following:
      • Pins 1-2 - 34 Ohms
      • Pins 3-4 - 17 Ohms
      • Pins 1-4 - 51 Ohms 
    • To test the PCB
      • In the top left corner of the Printed circuit board find terminal X20
      • Measure DC voltage across Blue and Red wires with power on
      • The voltage should be 24V DC and when the gas valve opens after the spark it should go down to 12V
    • If PCB has failed the test then replace the part: Vaillant EcoTec Plus Printed Circuit Board (PCB) 0020132764
    • The PCB is also faulty if the boiler is making a constant clicking sound and the temperature reading on the display are changing constantly while boiler is not foring up.
< Go Back2015-10-10

Vaillant Thermocompact VC GB 142 EH - wiring diagram

Vaillant Thermocompact VC GB 142 EH in conjunction with Vaillant Vantage VIH C120 Unvented hot water cylinder - no heating or hot water

  • If boiler is firing and working fine then:
  • Check the wiring in accordance with a wiring diagram below
  • Replace or check wiring for 3-port mid position valve
  • The part number is Tower VAL322MP

PDF - Vaillant Thermocompact VC GB 142 EH - wiring diagram - installation instructions

< Go Back2015-02-13

Vaillant ecoTec plus 824 - Con - display fault PCB (0020132764)

Vaillant ecoTec plus 824 has no hot water or heating

  • When turn the boiler on the display shows Con message
  • After the temperature figure starts jumping without boiler to be working
  • The PCB is faulty and needs replacement
  • The replacement part is VAILLANT ECOTEC PCB 0020132764
< Go Back2015-01-11

Vaillant TurboMax 242E - No hot water, faulty diverter valve 011289

Vaillant TurboMax 242E - No hot water but heating is working fine

  • Open the front casing and check the diverter valve micro-switch
  • Open a hot water tap and see if the diverter valve lever switches on the micro-switch
  • If the plastic lever doesn't move or not far enough then replace the diverter valve 
  • The replacement part is Vaillant Turbomax Diverter Valve 011289
< Go Back2014-12-27

Vaillant TurboMAX Plus 824E - faulty fan replacement 0020020008 (old: 190272)

Vaillant TurboMAX Plus 824E - no heating or hot water

  • Boiler doesn't go into a lockout
  • No red lights on a front panel
  • The green light is flashing indicating demand
  • The pump is running
  • Open the combustion chamber cover and check the fan is spinning
  • If the fan doesn't spin then check the voltage which should be 240AC
  • Check resistance between neutral and live terminals on the fan. A working fan should have around 40 Ohms resistance. A faulty fan will have around 2 Ohms.

  • If there is a voltage then replace the fan
  • Completely isolate the electricity to the boiler when replacing the fan
  • The part number is Vaillant 0020020008 Fan
  • Old part number is  190272
< Go Back2014-11-30

Vaillant TurboMax Plus 828E - faulty Printed circuit board PCB 130806

Vaillant TurboMax Plus 828E combination boiler fails to ignite with F28 fault code

  • Check the system pressure on a pressure gauge is in the green area. If not then top it up. Note that the pressure gauge can show a faulty reading if it is blocked
  • System pressure sensor could be blocked or faulty
  • Open the combustion chamber cover and try to start the boiler
    • If you can hear the gas valve opening but no spark occurs then replace PCB
  • The replacement part is Vaillant Turbomax Plus Printed Circuit Board (PCB) 0020034604
    • This part replaces the following old PCBs: 130806, 130805, 130821, 130827

PDF - Vaillant TurboMax Plus 828E - faulty Printed circuit board PCB 130806 - installation instructions

< Go Back2014-11-16

Vaillant TurboMax Plus 828E - Faulty pressure gauge 101271

Vaillant TurboMax Plus 828E doesn't fire up. No heating or hot water

  • Pressure gauge shows 1 bar system pressure
  • Drain the boiler and check that the pressure gauge arrow is moving to 0 bar
  • If the arrow remains still at 1 bar when the system has been drained then replace the pressure gauge
  • The replacement part is Vaillant 101271 Pressure gauge
< Go Back2014-10-17

Vaillant Thermocompact 628E - Combustion gases testing point plug 139472 replacement

Vaillant Thermocompact 628E has missing combustion gases testing point plugs 

  • There are two test points:
    • one on the right is for products of combustion
    • another one on the left is for incoming air
  • The replacement part number for the plugs - Vaillant Plug 139472
< Go Back2014-08-14

Vaillant ecoTec plus - filling loop replacement

Vaillant ecoTec plus combi-boiler is constantly discharging water from outside pressure discharge pipe. The pressure stays on the red all the time.

  • Check that filling loop valves under the boiler are closed
  • Undo a flexi-hose from one of the sides and check if any water is coming from any of the ends with filling valves in closed position
  • If there is water then replace the filling loop valves
  • The part number for the right-hand side 0020010295 Vaillant Isolation Valve
  • The part number for the left-hand side 0020010291 Vaillant Service Cock
< Go Back2014-07-06

Vaillant ecoTec Plus 831 combi boiler - flexi connector replacement

Vaillant ecoTec Plus 831 combi boiler - flexi connector replacement

  • A boiler has lost all the pressure 
  • Water is leaking from the boiler when you try to top it up
  • Open the casing and inspect flexi connectors on flow and return pipe inside the boiler
  • If they split replace the part
  • The part number for replacement is Vaillant Flexible Tube Complete 080387
  • Note that this part is from a different model but it fits the ecoTec range


< Go Back2014-05-03

Vaillant ecoTec plus 824 - Diverter valve replacement 0020132682

Vaillant ecoTec plus 824 - water is not getting hot enough and central heating works when its off

  • Make sure the system is cool
  • Open a hot water tap and touch a boiler's flow pipe
  • If the pipe is getting hot then replace a diverter valve
  • The part number for replacement is Vaillant 0020132682 Diverter Valve CPL
  • Old part number: 178978


PDF - Vaillant ecoTec plus 824 - Diverter valve replacement 0020132682 - installation instructions

< Go Back2014-05-03

Vaillant ecoTec plus 824 boiler - F.20 fault code

Vaillant ecoTec plus 824 boiler displaying F.20 code. No heating or hot water

  • The boiler overheats due to a poor water circulation or a faulty NTC flow temperature sensor
  • Replacement part number is Vaillant NTC Sensor 193592
< Go Back2014-03-08

Vaillant ecoTec old boilers - Vaillant Gasket Seal 0020038679

Vaillant ecoTec old boilers every 5 years require a burner gasket replacement

  • replace the burner gasket every time the burner lid removed for a boiler maintenance or service
  • the replacement part number is Vaillant Gasket Seal 0020038679
  • this part number suitable for the whole ecoTec range including ecoTec Plus 937
< Go Back2014-03-08

Vaillant ecoTec plus 824 boiler - fault F.75 (no heating and hot water)

Vaillant ecoTec plus 824 boiler - fault F.75 and the boiler doesn't fire up

  • the boiler can't detect a pressure rise when the pump is on
  • recharge the expansion vessel with a bicycle pump
  • replace the water pressure sensor or clean the existing one
  • the part number is Vaillant Water Pressure Sensor 0020059717
< Go Back2014-01-12

Vaillant Thermocompact VC GB 242 EH - gas valve fault

Vaillant Thermocompact VC GB 242 EH gas valve is letting by when the boiler is off.

  • the gas valve is faulty it doesn't fully close
  • need to replace the whole part only
  • the gas valve replacement part is 053255
< Go Back2014-01-02

Vaillant ecoTec plus 637 - PCB replacement

Vaillant ecoTec plus 637 doesn't show any signs of live. The incoming voltage is ok but LCD is off.

  • It is a main PCB or a screen PCB has gone down
  • To test wich one measure DC voltage between earth and one of the wires of X20 in the top left corner (red plug). 
  • If there is 5v DC then the screen PCB is faulty
  • If there isn't any voltage then replace the main PCB
< Go Back2013-11-23

Vaillant ecoTec plus - pump replacement

Vaillant ecoTec plus 831 boiler was making a loud noise when operating.

  • The pump was making the noise
  • The pump started to leak in few days
  • Pump replacement part number is 178983
< Go Back2013-10-18

Vaillant combiCompact VCW - No heating but hot water is working

Vaillant combiCompact VCW - Hot water is working, on heating demand the pump is running but no ignition occuring.

  • Make sure that the diverter valve micro-switches are making the circuit, both of them. You can see it once turn the heating on. The spindle will push 2 bittons inwards. 
  • If this is not happening then you can adjust two screws so they press the buttons
  • Also remember that this boiler has a heating delay set by manufacturer on 5min. It means that after turning the heating off it will only come on again minimum after 5 minutes.
  • You can adjust it on the front panel.
< Go Back2013-10-17

Vaillant ecoTec pro 24,28 plus 824,831 - error code F.75 faulty pump (178983)

I have Vaillant ecoTec pro 24,28 plus 824,831 combination boiler which have stopped working and displaying error code F.75

  • Check the pump first. Reset the boiler and check voltage between blue and brown to the pump. If it showes 240V intermittently avery 5 seconds and you can hear an intermittent buzzing noice from the pump then the pump need replacement
  • The part for replacement is: Vaillant 178983 Ecotec Pro Plus PUMP ORIGINAL
< Go Back2013-08-15

Vaillant TURBOmax Plus 824E - broken filling valve

Vaillant TURBOmax Plus 824E - broken filling valve. If the built in filling valve is broken or impossible to open then you have 2 options whether to replace the built in valve or to fit an external one. To replace the built in valve isolate the boiler on flow and return pipes and drain it down replace both valve on a cold water side and the central heating side, open the boiler and refill the system up to 1.2 bar. To fit the external filling loop drain the whole central heating system ad tee off from both the central heating return and cold water pipe to 15mm copper and fit the filling loop so the double check valve is on the central heating pipe side. Refill the system. For the built in filling valve see details below:

The part number is 014675 and you can order it from here.

Vaillant TURBOmax Plus 824E manual: PDF

< Go Back2013-04-03

Vaillant TURBOmax Plus 824E - no heating, no hot water

Vaillant TURBOmax Plus 824E - no heating, no hot water, boiler is not firing up. Start the boiler and if the fan has gone you will hear buzzing noise. Open a front cover and remove a combustion chamber cover. Start the boiler again and watch the fan impeller. If you can see it has stacked then try to lubricate it and give it a spin. The fan should start spinning and the boiler will fire up. If the fan makes a strange noise at all then it will likely to stuck again very soon and you need to consider the part replacement. Measure the CO/CO2 ratio and if it is not more than 0.004 then you can leave it as a temporary fix until the part replacement.

The part number is 190215 and you can order it from here.

Vaillant TURBOmax Plus 824E manual: PDF

< Go Back2013-03-30

Vaillant Boiler goes to lockout after 2 hours after reset

Boiler has started to shut down with the overheat lamp lit. This happens after the boiler has been running for at least 8 hours. Once reset, it will run again for a number of hours before tripping out again. The problem is more likely the central heating system than the boiler. Basically the hot water is not getting out of the boiler fast enough so that when the flame goes off the residual heat in the boilers internal heat exchanger causes the water to become overheated and trip the safety device.

  • Has the pump speed been turned down? Turn it up to maximum.
  • Do you have radiators and /or towel rail that have manual valves on (not thermostatic) to accept a flow of water when other rooms with thermostatic valves on have warmed up? If so are they open?
  • Have you recently insulated some pipework that is meant to be uninsulated as part of a heat sink / by pass system.
  • Is there a lot of air in the system preventing proper circulation?
  • Is the system working properly otherwise? sludge in the system may prevent proper circulation.
  • Is the flue is not blocked?
  • Does the pump connected to overrun?
  • Is by-pass valve opened?
< Go Back2013-01-28