Dripping flue, any thoughts

[Riley]

Called to a customers today to look at their boiler. It's installed in the loft with a standard 90° elbow out the top of the boiler and straight out the wall. Both inside and outside are sealed correctly and flue is set at 5° incline as per MIs. Problem is that on the inside of the 90° bend there appears to be no more than a drip but definitely some condense running back down to the top of the boiler where staining is evident. I have checked the joints of the flue thoroughly and am satisfied that they are tight and under no strain from the incline. Does anyone have any thoughts where this drip may be coming from?
On a funnier note I've never seen anything like this guys loft he has a plastic container under EVERY joint in the pipe work. Just in case they leak. It's a pressurised system so I asked what happens if the joint gives at the side or on top, I don't think he understood. Cheers all

 

[stoker122]

Driving rain getting into the air duct?

 

[nysk2008]

Are you able to get an FGA reading?

 

[Riley]

Might well be the case, it was just the staining that concerned me a little

 

[Riley]

Nysk2008 apologies for sounding thick. I can with the use of a ladder but what would you be hoping that this would show?? I serviced the unit approx 7 weeks ago and was all ok. Basically i am concerned with where the liquid may be coming from which is not immediately obvious Thanks for replying

 

[nysk2008]

Hi mate no probs at all - what boiler is it

 

[Riley]

Ah now you've got me. Minds gone blank, I've done about 6 jobs today and they all blur into one. It's definitely an ariston on an unvented system and I believe it was only installed in 2007. Sorry I'm not much help its been a long day

 

[nysk2008]

it cool, don't worry, firstly imho aristons are sh**e, if you are able to get an FGA that would be good as Ive seen (not on an ariston) the inner flue corrode and condensate leaks down the air intake, obviously an ID situation but not seen many like that, if the flue seals are knackered this could cause water/condensate ingress. I would also be inclined as stoker said to make sure the flue is sealed correctly to the outside world as bad weather could cause a bit of water on top of the boiler. Id also check that if the flow and returns are run above the boiler make sure there are no weeps on the system and dripping down, I assume not though as the cust would have advised of pressure loss in the system. im pretty sure there is an fga test point on most aristons, make sure this is sealed and that some dick hasn't left it out. Not sure how long you have but run the boiler at full rate and see what you get, checking all flue, flue sealing, pipework etc. don't forget aswell the boiler is in the loft, do the have a weep on their roof? never rule it out buddy

 

[Riley]

That's a fair point re hole in the roof would explain the discoloured liquid. All the other things you mention are ok with the exception of the FGA which ill check in the morning, couldn't see an FGA point immediately but at the time I wasn't looking for one. Weird that it should be just on the underside of the flue pipe and nowhere else though. Cheers for your help though mate

 

[armourer]

Could just be condensation.

The lofts cold if its well insulated and your flue will be warm enough to condense the air?

Just a thought.

 

[Riley]

Thanks Armourer another good option