Acidic boiler condensate on plastic window ledge

[Mr Pounder Esquire]

Thanks for that.

[James Wilkinson Sword]

Do you disagree with my statement? You have a treehugger boiler.

[John Rumm]

Which vent pipe?

Is this the pressure release vent as fitted to most sealed system boilers, or is this a condensate pipe from a condensing boiler?

If the former then (aside from the point that it ought to never have anything come out of it unless there is fault wit the heating system), then the staining would probably come from black iron oxide corrosion products in the primary makeup water.

If its a condensate drain, then (aside from being installed wrongly - it should be piped to a drain, not left to drip on the house), then its a very weak acid - but ISTM unlikely to stain uPVC

(or do you mean the balanced flue? In which case, yes you can get condensation drips from them on old non condensing boilers (condensors ought to have them sloped back so the condensate runs back into the boiler))

It may. I would be tempted to try a solution of oxalic acid before going for a chlorine bleach though.

[Richard]

Unlike you and Pounder.

[harry]

They are illegal in the UK.

[harry]

uPVC is quite porous. It has a laquor on it when new to keep it clean. When you get the stain out, it needs relaquoring.

Could be the condensate has taken the laquor off.

[John Rumm]

This is untrue. (well its harry!)

If you have one already installed, then you can carry on using it.

If you are installing a new one, then there are circumstances where you can still install a non condensor. You need to carry out a points based assessment first. Details of the process here:

[James Wilkinson Sword]

If you don't tell anyone you installed it, they won't know. And AFAIK it doesn't apply in Scotland anyway. There is no way I'd follow a law intended to make something more efficient. I pay for the gas ffs!

[ARW]

It will remove the symptom not the cause.