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Put your Central Heating System question in here.

I have a problem with a leaking boiler (Vaillant Eco TEC Plus 824), which is about ten years old, but it hasn't had a lot of use (house empty a lot of that time).

There is a slow, steady drip from the right-hand side underneath the casing and an intermittent drip on the left side of the boiler. This stops when the boiler is running. There is no error message.

It doesn't drip straight away when it's off, as it's been off for a couple of days now and only started dripping today. It's done it before and so I called out a plumber but he couldn't find anything as, of course, it wasn't dripping when he called!

Any ideas please?
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has it lost pressure at any time?
was he a plumber or gas safe eng? not hard to find where leaks have left staining unless its just started doing it & yes, i do have an idea where its coming from! ;)
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Then he may have done half a job or still wet behind the ears (young).

The flue seals on the inside of these boilers fail and should be tested with an analyser for the co/o2 within the flue- did he do that?

Does it have a long or vertical flue length?
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LCHH wrote:
February 10th, 2020, 6:18 pm
He was relatively young I guess. No, I don't think he tested for that, but he may come back tomorrow to have another look.

Not sure about the long or vertical flue length? I think it's quite short, just comes out of the top and out of the wall to the outside.
Hmm, not likely that then but still worth checking. does the flue go straight outside behind boiler? if not then it has an extetion seal !!
he needs to find if its high or low on the boiler, if its high then it could be condense coming down the flue or the pipe into heat exchanger seal (stops dripping when it expands.
if its low, i would be looking at vent on the pump or diverter cartridge.
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LCHH wrote:
February 10th, 2020, 8:43 pm
The flue is high, comes out of the top of the boiler and immediately goes through the wall. So that narrows it down then - thank you. However, what would the answer be to this?
the flue angle and internal seal integrity needs checking if he cant find internal leak.
Rain entering flue?
then the internal condense pipe inside the boiler for splits.

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