Condensate dripping from boiler flue - advice please

[robertm67]

I have an Alpha Intec boiler installed on my loft wall. The flue goes horizontally from the top of the boiler and passes through the wall, exiting high up in the gable end. The boiler was installed about 6 years ago.

My attached garage joins the gable wall directly below the flue. I had the garage re-roofed last summer with a rubber type material (Firestone EDPM).

Over the last few weeks, I have noticed that when the boiler fires up for the central heating most of the vapour disappears into the atmosphere, but there is a drip from the base of the flue exit on the exterior wall. I have timed it at around 2 drips per minute when the central heating is on. The drips accumulate on the garage roof and run down the slope of the garage roof and, if the heating is on for a long time, the liquid eventually runs into the garage gutter.

If the drips were just water I would not be concerned, but I have read that they are acidic and I am therefore worried that they will damage the rubber roofing material. I have collected the drips in a pot over a number of days and used PH paper to test them; the result was a PH value of around 2 or 3, i.e. acidic.

I have read that the flue should have been set at a slight angle to ensure that any remaining condensate runs back into the boiler. Looking at my boiler instruction booklet, I think the flue is an Alpha CD Easy-Flue.

I would appreciate advice as follows:

• Does the amount of condensate dripping from the flue seem to be too much? If so, is this likely to be due to the flue not having been set at a sufficient angle to drain back into the boiler?
• If the problem is the angle of the flue, how easy is this to rectify? Is it something that I should be able to do myself or do I need to use a gas safe engineer?
• Is it likely to be possible to rectify it just from within the loft? Access from the outside would require a ladder on the garage roof and I am concerned this could damage the new roof.
• If I have to get a heating engineer to do the job, how much should I expect to pay? I am in Notts; access to the boiler is quite easy as the loft is all securely boarded and there is a loft ladder and lighting.
• If the amount of dripping is actually normal, is there a way I can safely capture and drain the drips to prevent damage to the roof?

I have attached pics of the boiler and exterior of the same wall showing the flue.

Thanking you in anticipation.

 

[Brambles]

The condensate is a mixture of very weak nitric sulphuric acid ( from reaction with SOx and NOx in the combustion process) so, provided your roofing material is resistant to weak acids, it should be ok.

in essence, the flue has not been correctly installed - condensate that has condensed before exiting the flue should always run back to the boiler

 

[king of pipes]

In principle it's should not drip but in severe cold weather with the Boiler running its not unusual for the odd drip to form but these should be minimal, the position of that flue makes it difficult to examine it could be a failure of a seal or a component only way to check is remove it a pita i know but needs must, a flue gas analysis to check that flue products are not leaking into the air intake would rule that out , kop