Diverted valve dripping

[trevorbayliss]

My vaillant combi has a leak and I have just spotted where it is dripping from. The drip is on the brass body of the diverter valve.

Not sure why this should be leaking again as a new valve was fitted in January 2025, so just over a year ago.

Any idea why it might fail again?

The boiler is 16 yr old and has had one diverter valve before the last change in jan 25.

I will add a photo but I don’t think you can see the drip

 

[jj4091]

Did they replace the complete valve with body or just refurbish it with seals.

 

[CountryFan]

Any idea why it might fail again?

Usually poor water quality/detritus in the system.

 

[trevorbayliss]

It was a proper vaillant unit with the full brass body replaced.

My system is clean and has a magna pro 2 filter on it.

Boiler is 18 yo so I think I am now just going to replace

 

[Madrab]

Depends on where it's leaking, tends to be seals, moot really though given it's being replaced.

 

[ChrisJP]

Boiler is 18 yo so I think I am now just going to replace

Seems a bit extreme to replace the whole boiler just to cure a leak on a diverter valve!

 

[trevorbayliss]

the diverter was changed a year ago and now it is leaking. its 18 yo and I have a constant pressure drop on the boiler which I cannot solve. Been going on for over 2 yrs. I cannot find any leak on the system. Every 2/3 weeks I need to top up half a bar generally. I swapped out the expansion vessel and AAV over a year ago in case these were the issue. Still no change.

The diverter a year ago was the fully brass body made by valiant. When the diverter went last time I thought about just swapping the boiler but decided to try a new diverter. prob wrong decision. My system is clean and I did the filter the other day. It had a bit of magnetite on the magnet, but nothing excessive.

 

[CountryFan]

the diverter was changed a year ago and now it is leaking. its 18 yo and I have a constant pressure drop on the boiler which I cannot solve.

A leaking diverter will cause the pressure to drop