Rain through combi flue - is this common?

[mattylad]

Hello, I wonder if you RGI guys can tell me if rain coming through a combi flue is a common occurrence?

Either I have real bad luck or its happened to every boiler I have had.
First one on an end terrace, rainy & very windy say - water down flue onto fan - kaput...
Next it was a vertical flue, properly fitted by corgi RGI's and twice water dripped down flue on very rainy windy days & blew fan (so twice I had to rewind it).

And then a couple of days ago on yet another windy/rainy day water in my combi with absolutely no other signs of a leak or any since then.

Do I just have real bad luck or does this happen often?

(All boilers fitted by supposed Corgi companies).

 

[Agile]

I take no heed of who fitted the boilers.

The manufacturers carefully specify how the flues are to be fitted. This can be very important to prevent water ingress. If this is followed correctly then water damage should never occur under normal conditions.

A common problem is blocked gutters overflowing and water cascading onto flue terminals. Also flues being fitted in unsuitable locations which any normal person would see as posing a risk of water ingress problems.

Vertical flue problems are usually the result of incorrect assembly and sealing.

Tony

 

[mattylad]

So have you come across this often before then?

 

[ChrisR]

It's very common to get a little water in through a correctly fitted flue, but a few drops don't usually cause a problem.
Careful assembly inspection required, though some aren't designed very well.

 

[simond]

In certain locations in adverse weather (torrential rain) a horizontal flue terminal can suffer from water being blown into the terminal.

Some boilers can deal with this better than others. It is not a common problem but is mainly down to local buildings or other masses creating unusual wind patterns.

When looking at an oil boiler flue where it has been run up a chimney, you will sometimes see staining on the exterior bricks on the upper levels. This is symptomatic of the flue gases being caught in draughts and swirling air currents, and effecting the pull and dispersal of gases.

So to summarize, a flue is very dependant on weather conditions. Just like some windows let the rain in when open, other identical but differently sited windows do not. Sometimes this is difficult to predict.

 

[Paul Barker]

to be fair

in the early condensing boiler flues the air intake holes were allround the circumference of the outer flu.

simultaneously manufgacturers demanded the complete opposite installation behaviour of tilting the flue back to the boiler because they were so scared of a flow of condensate water from the end of the flue to the floor beneath (imho the lesser of two evils but everyone became anally retentive about condensate which as far asI am conscerened you can let drip out theflue onto your garden and grow Rodo's beneath the boiler)

So of that generation boiler most of the insides are shot to bits with corrosion as rain ran bac through the outer flue into the boiler.

Some manufacturers everntually realised after years of rotting boilers that they had better sloap the inner flue pipe and ask installers to forget what they had been told to do in a knee jerk reaction and revert to the horizontal flue.

Sadly many installers don't read instructions each time they fit a boiler which they have been fitting for years so don't realise the change. Quite honestly i don't blame them. I lay responsibility for this massive industry coc up full square at the feet of the manufacturers.

But now hopefully the more illuminated manufacturers have subtley (because they don't want any claims against the thousands of ill conceived boiler/flue combintaions they have been selling for quite a few years) changed their flues to the new design with air entry ports in the lower 180 degrees and slanted the internal pipe so that rainwater is not chanelled back through the outer flue into the parts of the boiler not suited to it.

I feel for you but I have seen many boilers wrotten to bits inside through this complete failure of the design teams.

If you had asked me for a boiler atthe time you would have got one made in Holland where at the time 80% of boilers were already condensing of a design which has a 20 year track record where these type of pitfalls for idiot designers had been forseen and engineered around.

But in the uk the trade is full of puffed up pugnations die hards who come to your house and say "here you are luv this is what you want" with out any realability to discern a truly exceptional boiler which is what they claim for their one.

 

[Paul Barker]

As for vertical flue

once again it is not unheard of for manufacturer error in this department. They again subtely changed the vertical flue terminal without telling anyone and the merchants probably continued selling old stock.

in our town seagulls actually pec at the rubber seals of the modern aluminium flue slate I have to use lead or protect the rubber with chicken wire.

Also if it is a flat roof the flue can be fine but a leak elsewhere will track along and where the surface tension is broken (your flue) find it's way into the building.

i have had all these scenarios usually 100 ft up in the air on cliff edge blocks of flats and while I'm up there trying to work out the cause of the water ingress i am being dive bombed by anctious parents.

 

[simond]

Talking about Dutch boilers, Paul.

Have you heard that Worcester have pulled the Buderus domestic boiler range in the UK and dispersed all the sales team?

 

[Paul Barker]

Unreal.

 

[mattylad]

OK cheers for the info guys, I take it then that my problems are nowt special & only to be expected given the age of the unit.

 

[Agile]

I would not say that.

Every time I have been caused to a problem with water entering the flue there has been an installation problem OR a problem with gutters etc..

Tony