Vaillant EcoTec Plus Overpressure means I'm under pressure!

[The Incredible Hulk]

Dear all I have the following problem and would welcome your support. I have a combo boiler as described in the title. This morning I noticed that it was wet below the boiler and I then noticed dripping water from the underside of the boiler. I opened the access panel and saw that the pressure gauge was off the scale beyond the red zone! I searched the website and found someone with a similar problem was advised to ease the pressure by draining water out at one of the radiators. I followed this advice (after purchasing a key) and hey presto pressure reduced from circa 2.6bar down to 1.2bar. Dried under the boiler, no leak present! Went out for the day came back and checked under the boiler, you guessed leaking again. Opened the access panel and checked the pressure, 3bar! So, once again drained to relieve pressure back down to 1.3bar, leak stopped and all well.

Can someone please tell me what is going on when a 'closed' system on it's own accord manages to double in pressure? I'm clueless what to do over the weekend however cone Monday I will be calling on my vaillant service contract to help. In the mean time I'd rather minimise any damage.

Many thanks in anticipation for any support, by the way as you've probably guessed I'm not a plumber,....

Regards, Kevin.

 

[Terry7556]

On the page that list the posts look at the top
There is a sticky about FaQs on central heating, read the question about expansion vessels and how they lose their charge
That will help you to understand what's going on

 

[ianmcd]

its unlikely to be your expansion vessel either your filling loop is passing or you have a perforated plate heat exchanger, disconnect the filling loop and see if it still does it.

 

[dreadnoughtheating]

As the OP syas this is an Ecotec PLus, it has a built in 'filling loop', with 2 grey levers with shut or closed written on them... (to my shame I cannot remember which, and I have fitted a few ).

The wording on both should face the front of the appliance, i.e. be shut. If either or both are letting some water through this may be a cause of the pressure rise.

Then if not, we go into other possible causes, exp vessel, pinholes plate exchangers etc.

As a last thought. is there another older filling loop still in place hidden away perhaps where another combi boiler was? if so remove the loop and see what transpires.

DH

 

[The Incredible Hulk]

Thanks for your speedy and informative replies. I checked the fill loop valves, two in number and both firmly in the closed position, well one was ever so slightly open I noticed bur both now facing me with the word closed on each clearly visible. Previous boiler was a storage tank unit, how I miss it but the replacement was not a choice I had. The boiler is only about 3 to 4 years old and has behaved immpecabily to date. Embarrasingly unless there is something obvious (read easy) to do over and above draining the pressure I suspect it's call out job against the service contract on monday. Although I have no experience or knowledge to back it up I too suspect the valves controlling the fill loop are failing. I'm still recovering from paying for a new shower valve which failed last week - Mmm, seems to be a pattern here, can you have too much pressure in the mains that breaks everything piece by piece,....paranoia on a Saturday night eh. Many thanks all.

 

[Steelmasons]

Sorry I can't assist OP but the thread title is fookin awesome.

 

[Happyplumber]

I have had this problem on couple of the older Ecotec models down to the filling loop passing through the check valve


disconnect the filling loop and see if it is passing

 

[Tipper]

Had the same issue with my 937. It was the expansion vessel which had failed inside. A new one from an eBay supplier and all fixed for £50ish.

 

[Steelmasons]

Ecotecs are notorious for the fill valves to let-by , go get yourself a replacement set (70 odd notes).

 

[muggles]

3-4 years old? Was it installed by a Vaillant approved installer? If so, it should still be under warranty, call Vaillant out to fix it if it is

 

[The Incredible Hulk]

How bloomin annoying, after releasing the pressure before going to bed I popped down to check it roughly 6 hours later and you guessed it pressure has climed once again from 1.2bar up to 2.5bar. Something has clearly failed . A call on Monday then and a frequent use of the radiator key until then - royally p'd off. Many thanks to all for your contributions, I genuinely learn so much when I post.

 

[Terry lambert]

Sorry if someone has said it already.

Unscrew the two grey knobs on the filling loop to make sure they are turning the brass nibs fully

The plastic rounds off and doesn't shut the loop properly, do so with a small spanner

 

[Agile]

Yes, the most common cause is that the grey plastic knobs are not successfully turning the valve shafts.

Tony

 

[The Incredible Hulk]

As per advice unscrewed the grey plastic knobs and checked tightness with a small spanner, sadly all well so I suspect it may well be internals. I'll back brief when I know more. Regards, Kevin.

 

[Bunnyman]

I'm sorry tony but its usually the fill loop passing very very rarely the plastic knobs 😀😀it also won't be the expansion vessel that won't cause this fault, and the dhw letting by is rare as hens teeth