dripping flue

[ambrosia]

attended a flat where the customer had reported a leak, turned out to be the flue which had quite a long run with 2 elbows and a coupling on it, all internal with no boxing. (pretty ugly)
the flue was level rather than tilted back to the boiler and had sagged slightly. The water was sitting in the flue and was slowly dripping out.

My reasoning was if its dripping water it cant be air tight, so switched it off and told landlord to call the installer to come put it right.

However the installer rang me up ranting about how out of order i was etc, that i'm making a mountain out of a mole hill etc

i dont really careabout the installer, thought he's an idiot before this. But i was wondering how most people would classify this situation, to me a flue that is leaking in an internal room is an ID

(also I need to talk to vaillant to see what the max length of a flue on an eco tec plus 24 is)

 

[mountainman]

Well done mate, the installer is totally at fault.
Got to be made safe as flue is not correct.

 

[ambrosia]

thanks Mountainman,
but would you classify it as ID, had there been no leak because the sag was slight i might have overlooked it on a cp12.

 

[Millsy 82]

I would have classed it as ID. The chances are that a joint has been pinched as I had this problem a few months ago and we sorted out the fall back to the boiler but it carried on leaking changed the seals and it was fine.

The overall length of the flue is quite a distance (Around 12 meters I think for the 24 but I would double check that)

 

[mountainman]

I'd say AR as IMO, ID would pose an immediate risk to the occupants, I don't believe a condensation drip from a flue seal could be classified as such.

However, if you download the MI's for the boiler you will probably find that the installer made a poor job of the flue which COULD have resulted in an ID.

All said though, there should be a continuous fall back of the flue into the boiler, each joint should be secured by a screw secured clamp and appropriately supported.

 

[kozak1968]

Dripping flue would indicate a break in the exhaust / inner flue. Condense would run down exhaust and usually back to boiler and trap. If it only happened when it rained it could be the outer flue damaged. Put the analysiser probe in the intake of the flue turret to see if the co reading goes up and this would indicate a corroded or damaged inner flue. I would

 

[HeatStar]

Agree with above. If found to be a brake in exhaust inner tube after FGA then it's ID.

By the way the max horizontal flue length on an Ecotec plus 824 is 8m with one elbow on the standard 100mm pipe. Seeing as the system in question has 2 elbows then your max allowance should be no more than 7m as each additional elbow after the one allowed subtracts 1m from the max length.

 

[Sniks]

Hi.. have fitted loads of vaillant boilers over the last few years and I have noticed recently, on any flue length over standard rear or side 600 to 800mm long that some of the joints are leaking.. I have also noticed on inspection that the flue seal rubber has disintegrated allowing water to drip into the outer flue and then out of the external joint. It doesnt appear to have any bearing that the flue was screwed together externally, and surely if it is supported correctly it shouldn't leak as a seal should be a seal regardless of orientation !!
i am going to take this up with vaillant as it may be a problem with the recent manufacture of rubber seals.

 

[AWheating]

keep us informed on there responce.

 

[Nostrum]

Had a load of vaillants of all ages suffering from this. I always A.R once I've analysed the air intake which never shows up any issues. Poor seals I think that don't last the life of the boiler. Probably partly caused by rough cut flue lengths jammed together with no lube. Seen quote a few with corrosion damage to outer metal as well.

 

[stevetheplumber]

any flue dripping condensate is ID in my eyes if the condense can escape the flue isnt sound you wouldnt leave a bbu running if it failed a smoke test with smoke escaping from the flue internally

 

[GrahamM]

Although is an old thread got to agree 100% with steve.
If a flue is dripping condensate internally the flue is not sound. If can drip condensate it is possible that could spill combustion gasses.
Clear ID in my opinion!

 

[Chris Kafetzis]

I too agree with ID, also I've come across 4 vaillant boilers with this problem, twice on my own installations. I always file down the edges of the inner flue and use silicon grease on rubbers. Recently however I went to service a boiler I fitted 3 years ago with this problem. When I rang vaillant they wouldn't do anything because apparently vaillant don't make there own flue so it's not covered in the warranty! I feel short changed really, this is clearly a manufacturing fault in my eyes. The seals had shrunk and wrinkled up, then the condense had rusted a clear hole in the side of the flue that I could fit my finger in! Might start with Worcester soon I think.

 

[Anton]

I too agree with ID, also I've come across 4 vaillant boilers with this problem, twice on my own installations. I always file down the edges of the inner flue and use silicon grease on rubbers.

According to the installation manual for the Air/Flue Gas System supplied by Vaillant:

"Mineral oil-based lubricants may damage the seals. The seals should therefore not be lubricated.
Only use water or commercially available soft soap, if necessary, to assist with the installation."

 

[kris]

Its an old post but defo I D as if pipework sagging / dripping condensation then its not supported properly so Deco I'd. . If it hadn't been sagging and was supported then I would've A R it.

 

[GrahamM]

According to the installation manual for the Air/Flue Gas System supplied by Vaillant:

"Mineral oil-based lubricants may damage the seals. The seals should therefore not be lubricated.
Only use water or commercially available soft soap, if necessary, to assist with the installation."

As mentioned an old post.
But, going back to my chemistry days silicone grease is a fairly safe lube to use on rubber and fairly non-reactive. If anything it protects the rubber.
I use it daily for seating all seals & until anyone comes up with any substantial proof that it now has a detrimental effect on rubber I will continue to do so.


Just don't use any hydrocarbon based lube! e.g. Vaseline

 

[GasmanxxxR1]

Went back to a boiler that i installed 4 years ago, baxi solo with a long plume kit. Water was leaking from the case. When i undid the combustion chamber it was FULL of water, the fan had nearly drowned!. In the end i found it was condensation from the inner flue leaking from the seal of the elbow on top of the boiler. it had completely perished, it was just blue mush.

I installed it and I know I only use silicone grease or nothing at all. What could make the seal perish like that?

 

[bigads28]

Went back to a boiler that i installed 4 years ago, baxi solo with a long plume kit. Water was leaking from the case. When i undid the combustion chamber it was FULL of water, the fan had nearly drowned!. In the end i found it was condensation from the inner flue leaking from the seal of the elbow on top of the boiler. it had completely perished, it was just blue mush.

I installed it and I know I only use silicone grease or nothing at all. What could make the seal perish like that?

That seal is of pretty poor quality, must be a combination of heat and the condensate. I've found that if your combustion readings are high or you spot water in the case then its usually from that seal. If you don't catch it soon enough it wrecks the heat exchanger.

 

[thorn]

GasmanxxxR1, Just wandering how these faulty flues were resolved with customer, did they pay for replacement or try to point fault at you.
shocked to hear vaillant don't cover flue under warranty - abit **** to say the least

 

[kirkgas]

ID all day long, by seeing fluid he has confirmed the flue isn't sealed