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What common problems are there with Vaillant boilers?

3 Answers

Answered by South Yorkshire Heating

13th November 2019

South Yorkshire Heating answered the question "What common problems are there with Vaillant boilers?"

On a lot of the more modern Vaillant combination boilers they have the diverter valve that leaks through a very small o ring. To cure this you have to change the whole valve. Also F75 often is the pressure sensor which will need replacing. Also worth checking expansion vessel is right pressure. Also for a short while they had Wilo pump which was problematic. It leaked and rattled. You need to change it to Grundfos with new complete housing.

Answered by Louis Gas & Heating LTD

8th April 2019

Louis Gas & Heating LTD answered the question "What common problems are there with Vaillant boilers?"

F75 pressure sensor usually becomes blocked from dirt in the system. Once this is replaced usually recommend to fit a magnetic filter and system cleans ie magnacleanse or a power flush. Another common problem is the printed circuit board this can throw up a few faults that might suggest gas valve but it's usually the circuit board.

Answered by Stroud Boilerworks

1st April 2019

Stroud Boilerworks answered the question "What common problems are there with Vaillant boilers?"

Vaillant boilers are very common in the UK and often specified by landlords and a lot of installers like them as a top of the range option but even Vaillants have common faults! I see a lot of ecoTEC pro or plus models and the range has been improved over the years. They are not very forgiving of a dirty system so get a system filter and keep up to date with your boiler services. The pressure sensor used to be fitted in a location that attracted the dirt but it has been moved higher up the boiler. Early diverter valves leaked from the spindle. The early model used hoses to/from the heat exchanger but they were prone to clogging and again Vaillant upgraded the parts with the replacements made of copper. The burner seal needs changing every 5years so the part is an additional cost. There is a manufacturers recall on certain internal condense hoses which if left in situ; can leak and cause damage; often beyond economical repair. That said I still love Vaillants, they are common, well supported by the manufacturers and with good spares availability. They are well made with lots of brass and the diagnostics,s codes and p codes allow the boiler to be set up and interrogated to get the most from the boiler.

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