Vaillant ecoTEC Plus 618 pressure problem

[John XRV]

Hello everyone

First post so be gentle! Have done a search to see if my particular problem has been covered but can't find it so hence the reason for my post.

Had a two storey extension added to the house in 2009 and the old boiler was replaced with a Vaillant ecoTEC Plus 618. All was well until last year when it began to lose pressure and the heating and hot water wouldn't come on. I would add water and everything would be well for a few weeks or a month then the problem would return.

Earlier this year our plumber came and repaired it saying it was a valve and mentioned the expansion vessel. Everything ran well until about two weeks ago when the problem returned. I now have to top up the water every 2 or 3 days.

Anyway before calling in another plumber I decided to investigate. From posts on here I checked the pressure in the expansion vessel which was low (0.4) so I have increased this to 0.9 bar.

I also noticed that a valve on top of the pump (arrowed in attached photo) was covered in limescale crud so I cleaned this off. This is now showing a slight weep so perhaps this is my problem?

https://www.flickr.com/photos/160315577@N06/38559269061 [/IMG]

Thank you for any help and advice which will be gratefully received.

John

 

[terryplumb]

Pic shows an automatic air bleed valve. If water is seeping out that would result In lost pressure. If you turn the black cap clockwise until it wont turn any more ,it will prevent water being lost .only do this finger tight ,no grips. As a temporary fix .you can then see if pressure continues to be lost. The AAV will of course need to be replaced. I would check the pressure relief pipework outdoors ,see if any water is coming out there. If so , this will need investigating to establish why the prv is opening .

 

[John XRV]

Pic shows an automatic air bleed valve. If water is seeping out that would result In lost pressure. If you turn the black cap clockwise until it wont turn any more ,it will prevent water being lost .only do this finger tight ,no grips. As a temporary fix .you can then see if pressure continues to be lost. The AAV will of course need to be replaced. I would check the pressure relief pipework outdoors ,see if any water is coming out there. If so , this will need investigating to establish why the prv is opening .

Thanks Terry

Yes there is water dripping from the overflow / pressure relief pipe. Also in 24 hours the pressure in the expansion vessel dropped from 0.85 bar to 0.55 and the pressure gauge reading from 1.0 bar to 0.8

I've finger tightened the automatic air bleed valve as you suggest and pumped the expansion vessel up to 0.9 bar which increased the pressure gauge to 1.2 bar

I'll see where the numbers are in 24 hours so I can better inform the plumber

Thanks again

John

 

[terryplumb]

When re charging the EV you have to first de pressurise the system pressure . so you have a few issues the engineer needs to sort.regards terry.

 

[John D v2.0]

When re charging the EV you have to first de pressurise the system pressure

Agreed, on that note to save time and inhibitor You can just isolate the boiler from the system and drain that section.
Op, do you have water on the air side of the expansion vessel? Sounds like at least the prv is leaking by, the air vent can easily lose a bit when venting the air which isn't a problem.