Vaillant ecomax flue corrosion?

[Aire]

Hi guys, looking at a vaillant and the flue shows signs of corrosion on the air intake, I put my analyser in and o2 was coming back at 20.9% with no co readings so flue integrity is fine. It must be caused by water ingress from rain but wondering if I should at risk it or not.

 

[ShaunCorbs]

What happens when you pod with a screwdriver?

 

[Gasmk1]

could be ingress could be condensation is there enough drop on the flue to take the rain water away. i would tell customer that flue needs to be changed due to corrosion

 

[Aire]

Screwdriver didn't go through , it's about a 3m run of horizontal flue, this is the connection just after the elbow at the boiler, pressing along the bottom of the flue along the entire length, it's clear that the area where the corrosion is, the flue is weakened and if if squeezed hard enough it would probably break.

 

[Last Plumber]

I would AR it and give a warning notice explaining that it is safe at the minute (if it is) but requires urgent attention.
I would in this case give a date to comply by and make it clear on the notice. Only your judgment will tell you if that seems a reasonable thing to do as you're the man on the job.
It sounds like rainwater but again, you have seen it and tested it.

 

[Aire]

Pretty sure it's rainwater, if it was condense then surely the flue would fail integrity test. I wrote a warning notice explaining the flue is ok now but there is a risk that future it isn't, I don't think it's at risk of failure any minute but advised to replace anyway. Customer is weighing up whether it's worth it though as boiler is 15 years old and the temp dial for the heating does nothing too so probably not worth spending money on.

 

[Gasmk1]

Pretty sure it's rainwater, if it was condense then surely the flue would fail integrity test. I wrote a warning notice explaining the flue is ok now but there is a risk that future it isn't, I don't think it's at risk of failure any minute but advised to replace anyway. Customer is weighing up whether it's worth it though as boiler is 15 years old and the temp dial for the heating does nothing too so probably not worth spending money on.

condensation on outside of flue was what i meant not inside,

 

[Aire]

condensation on outside of flue was what i meant not inside,

Condensation caused by room conditions? That would be a hard one to spot, there certainly was no sign of condensation when I was there. Wouldnt the paint finish on the flue protect it from condensation?

 

[Harvest Fields]

I would AR it and give a warning notice explaining that it is safe at the minute (if it is) but requires urgent attention.
I would in this case give a date to comply by and make it clear on the notice. Only your judgment will tell you if that seems a reasonable thing to do as you're the man on the job.
It sounds like rainwater but again, you have seen it and tested it.

I did that. Then the customer got another engineer out who called Vaillant who said it’s fine. He then told me that the other engineer had switched it back on. I told him good for him. But I wouldn’t be signing to say it was safe. That looks like it is inside though. Mine was outside.

 

[Burger]

Pretty sure it's rainwater, if it was condense then surely the flue would fail integrity test.

It probably would fail, but then again how many times have checked out a normal "leak" only to find it leaks when you've left?

I also agree, doesn't look like atmospheric corrosion to me.

 

[Scott_D]

Can you unscrew the flue collar, slide it out the way and see what’s happening inside?

 

[Last Plumber]

I did that. Then the customer got another engineer out who called Vaillant who said it’s fine. He then told me that the other engineer had switched it back on. I told him good for him. But I wouldn’t be signing to say it was safe. That looks like it is inside though. Mine was outside.

Each to his own I suppose. There are all sorts of unknowns with a flue like that as I'm sure you know. If others disagree and leave it without further investigation, that is their own look out.

 

[Harvest Fields]

Each to his own I suppose. There are all sorts of unknowns with a flue like that as I'm sure you know. If others disagree and leave it without further investigation, that is their own look out.

Looks bad on the first engineer though when it gets turned back on

 

[GrahamM]

Pretty sure it's rainwater, if it was condense then surely the flue would fail integrity test. I wrote a warning notice explaining the flue is ok now but there is a risk that future it isn't, I don't think it's at risk of failure any minute but advised to replace anyway. Customer is weighing up whether it's worth it though as boiler is 15 years old and the temp dial for the heating does nothing too so probably not worth spending money on.

Just be aware!
I have had countless situations where combustion is spot on and air intake testing out 100%, but when delved deeper found pinched inner seals was cause.
Initially thought was just rain water ingress.

 

[Sharp Point]

Just be aware!
I have had countless situations where combustion is spot on and air intake testing out 100%, but when delved deeper found pinched inner seals was cause.
Initially thought was just rain water ingress.

I agree, a dislodged seal leaking condo doesn’t give out of sync fga readings

 

[Scott_D]

Pretty common on vaillant flues isn’t it?

 

[Harvest Fields]

This is why I would AR

 

[Aire]

Good to know for future if its a common fault. Hard to say how long the flue will last but warning notice was issued and customer happy with my explanation so can't do any more than that.

 

[Last Plumber]

Looks bad on the first engineer though when it gets turned back on

It does but the first Engineer was being cautious and correct in putting safety first. If the second Engineer puts it back on after a deeper and more rigorous inspection, he/she takes on the responsibility but knows the cause of the corrosion and must be satisfied there is no risk.
Some will just turn it back on regardless and they are very silly people.
I think the end user can tell if the Engineer is talking sense or not, most of the time.

 

[Millsy 82]

Vaillant flue seals are crap. They warp out of shape and a bit of condense passes through and causes this issue. It doesnt let gases through but condense seeps through.

 

[Harvest Fields]

Only ever seen it in a couple. Most are perfectly fine.

 

[Millsy 82]

Only ever seen it in a couple. Most are perfectly fine.

The time I see it is long horizontal flues.

 

[Harvest Fields]

The time I see it is long horizontal flues.

Not many of them by me mate. Mostly external walls or verticals.