Vaillant EcoTec810 plus leaking after heating is turned on - no heating !

[Timo1791]

Hi all - my second post here following on from my first issues in Feb. All your lots help was fantastic by the way so thanks for that, so here I am again.....

My setup:
Family house, with Vaillant EcoTec810 Plus boiler + one Siemens RDJ10RF thermostat

Context:
We had the Diverter valve, PRV, and expansion vessel replaced in Feb 26. No previous issues for past 8 years.
First leak last week, water leaking out of the boiler unit, opened the case to see a small jet of water spraying at me from the cylinder part of the PRV.
I checked the copper flow pipe outside and looked like water had discharged out over the slabs.
Called boiler engineer (company) who refilled the boiler, put it in service mode (where it runs the boiler without turning heating on), and he confirmed no more leaks he could see having tested it for 20 mins.
I asked if the PRV perhaps was seated properly, he advised this could be the case but still could see no leaks, so actions to recommend.

The problem:
Today (02/11) boiler has leaked again, within 5 mins of turning the central heating on. This is time no jet of water spraying from PRV, but the casing inside indicates the leak is in that same area (as it's the most wet / the protective foam is most wet).
No discharge from the outside copper flow pipe this time.
The pressure has dropped a little, but I turned the heating off quite quickly and turned off the isolating electrics.

Signals:
No symbols or errors codes from boiler. First leak had an F22 error when the water had fully depleted.

Can you please help me understand what is happening ? before I end up calling out another engineer and spending another £100 on call-out.
Is it worth changing the PRV ?
Is there other tests that should be carried out ? (at least I know it's worth calling another engineer to carry this out)
Could it be expansion vessel considering was changed recently ?
Is there any basic tests I can run to help indicate what this could be.
Thanks a lot in advance!!

 

[CountryFan]

How old is the boiler? Have a look at the condensate hose towards the back (black flexible tube) for any leakage

 

[Timo1791]

It's 16 years old.
I'll see if I can find it.
Only way of me testing it though i think is to turn the heating back on which might make the PRV release

 

[CountryFan]

It's 14 years old.

Definitley worth checking the condensate hose then

Only way of me testing it though i think is to turn the heating back on which might make the PRV release

You don't need the heating on to see if that is leaking, unless it's dried out. If the PRV is compromised, then it should have been changed with the vessel. Does the safety discharge pipe (copper pipe to outside) expel water?

 

[Timo1791]

The condensate tube is dry and not leaking.
I don't believe it was changed with the vessel as I took delivery of it and don't recall the hose coming with it.
On the first leak last week it did expel water but this time no.

 

[CountryFan]

The condensate tube is dry and not leaking.
I don't believe it was changed with the vessel as I took delivery of it and don't recall the hose coming with it.

I didn't mention the hose being changed, but the prb

On the first leak last week it did expel water but this time no.

Then it's likely something else

 

[spile]

O rings went on ours . Temporarily fixed by tightening and subsequently replaced.

 

[Timo1791]

O rings went on ours . Temporarily fixed by tightening and subsequently replaced.

I'm not familiar, for which part is the O ring needed ?
the PRV ?

 

[CarloHeatingEng]

The key difference between your two leaks: the first time, water came out the outside discharge pipe, meaning the PRV actually lifted. This time nothing’s come out that pipe, but the casing’s wet in the same spot. That points to a weeping joint near the PRV rather than the valve venting again.


Since the diverter valve, PRV and vessel were all changed in Feb, there are several new fittings there, any of which could have an O-ring not fully seated. Dry the area off completely, run the heating again, and watch with a torch for where the first bead of water shows up. If you can spot the joint, tell your engineer exactly where, it’s a quick tighten rather than a full diagnostic visit.

 

[Timo1791]

Called a different engineer.
Within 5 mins he said the PRV isn't fitted properly and requires pushing in more. He took a hammer and screwdriver to knock it in place. Saying he's surprised that it didn't explode off under pressure. He checked the expansion vessel too which he said is charged ok. We put the central heating back on seems fine so far no leaks anywhere and pressure is holding.
If that's what fixes it only time will tell, I'll monitor over the week and check if I see any drips around the O ring seals. It should leak agian within a day of using the central heating if its not the issue.

 

[spile]

I'm not familiar, for which part is the O ring needed ?
the PRV ?

It’s part of the heat exchanger. They come as a kit.