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Combi boiler slow leak advice


Simba_ali

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Losing .4 over 2 months is not a huge leak. 
If you have a magnetic filter then try the Fernox or Semtinel leak sealer products as that will end your turmoil in one day.
Likelihood is that it’s an evaporation leak; eg when the system heats up a joint / other weeps a timely amount but it’s hot so it evaporates and never manifests as a visible drip. Real pita to find those types of leaks as they could be anywhere. 
Leak sealer is the way forward here, as it’ll seek and seal regardless of where.

If no mag filter, maybe add to a towel radiator. 

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14 minutes ago, Nickfromwales said:

Losing .4 over 2 months is not a huge leak. 
If you have a magnetic filter then try the Fernox or Semtinel leak sealer products as that will end your turmoil in one day.
Likelihood is that it’s an evaporation leak; eg when the system heats up a joint / other weeps a timely amount but it’s hot so it evaporates and never manifests as a visible drip. Real pita to find those types of leaks as they could be anywhere. 
Leak sealer is the way forward here, as it’ll seek and seal regardless of where.

If no mag filter, maybe add to a towel radiator. 

 

Thanks for the reply 

 

Is leak sealer likely to damage the pipework etc?

My plan was to get an engineer to inspect the boiler for leaks (even though it was fine at the service last month apparently) and if all ok use a leak sealer to see what happens. 

 

Like you say it could literally be anywhere and I don't even know where the pipe locations are....

 

 

 

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7 minutes ago, Simba_ali said:

 

Thanks for the reply 

 

Is leak sealer likely to damage the pipework etc?

My plan was to get an engineer to inspect the boiler for leaks (even though it was fine at the service last month apparently) and if all ok use a leak sealer to see what happens. 

 

Like you say it could literally be anywhere and I don't even know where the pipe locations are....

 

 

 

It’s a product specifically designed for exactly this situation. I’ve used it many times and with excellent results. 
I did an old gravity to sealed and pressurised conversion and found water dripping from a ceiling downstairs. Was one of 4 pipes, 28mm, in a totally inaccessible place ( safe dropping the ceiling ) which had a floorboards nail completely through it. Had sealed itself with crud over the 30+ years it had been in. 
As soon as we filled the new system up, all great, then fired it up on max to get it all warmed through, and then it leaked like a bugger. 
One can of Sentinel later, and you could literally here the drips slow down over 20-30 mins and then stop. 
Client agreed to the fix and not heard a peep since ( north of 5 years ago ).

Dont waste money on the call out. 

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21 hours ago, Simba_ali said:

Sounds promising I'll look into it. 

 

How much water would you expect 0.4 bar to be on a 7 radiator system? Enough to show as a leak if it was from the plastic pipes? 

 

You can't tell. At best you can say its less than the volume of the expansion vessel because there is still some pressure in the system.

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Aree you sure that's a leak? I wasn't sure it necessarily looks like one given where the white stuff is/isn't. Obviously clean it up and see if it comes back.. 

 

Automatic air vents can often be sealed closed but your cap looks like it's got a hole so it might not be possible. 

Edited by MJNewton
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I'm not sure either, it looks old to me. The white stuff on top is powdery so I'm assuming it's to do with when the plaster boarding was done in the cupboard. 

 

It's more the green stains on the side that I'm concerned with. Looks like some kind of overspill at some point. It's Probably nothing just thought I'd get an opinion.

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Yes, I was thinking plaster too. The green might be a result of flux on the plumbers hands during installation. 

 

If you clean it up and tape a sandwich bag around it you'll soon find out if anything's coming out. 

Edited by MJNewton
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