vaillant ecotec plus 837 rapid pressure loss

[bigbird]

I have had my vaillant for 5 years. It was serviced after first year and again this year .
For the past month i have had to top pressure up at least once a week. This last week i have done it daily.
After i had it serviced last week, the engineer said i must have a leak beneath ground level.

After he left i didnt need to top the pressure up for aporox 4 days.

Since then its been daily again.

There is no evidence of leakage anywhere in property.

I have topped the expansion vessal up to 0.9 bar.

Pressure still dropping.

Now when i top pressure up the reading increases from 0.3 bar to 1.2 bar in approx 5 seconds.

I am wondering if this problem is sensor related ??


Can anyone please help ?

 

[plumber0808]

Is the pipe outside, the one that's bent back to the wall passing water?

 

[Whyme]

ive changed quite a few expansion vessals on newish vaillants, like above is that dripping.

 

[bigbird]

There is no signs of water leaking from inside of boiler nor from pressure relief or overflow.

 

[plumber0808]

Sounds like a leak under the floor then if you can't see any obvious signs of water anywhere

 

[Whyme]

There has to be some kind of leakage for the pressure to drop.like above hidden pipes or could be a problem inside the boiler which a gsr engineer could check for you.

 

[bigbird]

The only reason i dont agree is that the pressure held for a long time after service , but has since dropped more rapidly. This inconsistency in pressure drop and time fluctuates.

 

[bigbird]

Could there be a pressure sensor problem ?

 

[Whyme]

the water/pressures going somewhere unless its air venting which i doubt. does it fluctuate depending on heating demand or just randomly when the boilers not even on..?

 

[Whyme]

Could there be a pressure sensor problem ?

if its an analouge dial thats shows low pressure then no, the usual pressure sensor fault in vaillants is when it goes to f75 and it cant sense the pump running because the sensors blocked. which is gsr job.

 

[bigbird]

Its not the pressure which fluctuates but the time in which the pressure takes to drop from day to day.
One day it may take all day to drop from 1.4 bar to 0.5 bar, then the following day it may take 1 hour to drop to same level.

Only when boiler is running.

 

[bigbird]

Digital sensor.

 

[Whyme]

if its only when the boilers running its got to be an expansion problem, the other very rare occurance is an expanding joint only leaking when hot. does it go to fault .

 

[bigbird]

No fault.
Well only the usual f22 low pressure

 

[lame plumber]

pinholed main hex leaking back into boiler can cause this and you wont find a leak outside, very annoying to id

 

[CM25]

Isolate the flow/rtn under the boiler for a few days once the weather's warmer to prove if the leaks on the boiler or system, if uve had to top up the expansion vessel it sounds like prv letting buy. If the pressures still dropping with it isolated it's likely main heat ex pinholed and going out the condensate.