Sealing core drill holes for flues

[Pssst]

Its been quite a while since i fitted a boiler so havent checked the latest ,manufs insts but thinking about the annular space around the flue duct as it passes through the core drill hole,it only seems like sound practice to me to seal it inside and out often with expanding foam. Why do so many people just fit the inner and outer flex covers and if you find one with just the flex covers would you issue a notice? If so,what? Clearly if there is a draught and obvious signs of poc re-entry thats a much more clearly defined case than one which is apparently sealed adequately with just the covers

 

[Barry98]

if its unsealed its AR

 

[julesverne]

i use sillicone or cement then flue cover

 

[Roger Welton]

Mortar mix

 

[AWheating]

also sealing up with compo makes it wata tight and secures the flue safer.

 

[stegas]

One coat plaster on the inside, and mortar on the outside, then your rubbers.

 

[Pssst]

Just quickly reading flue instructions for Vaillant ecotec and Worcester cdi,although they mention a hole diameter for a core drill,they seem to suggest that only the rubber seals are needed as no mention of infilling the annulus so im guessing that an installer could not be criticized for not having done so ?

 

[P J F PLUMBING]

I've seen a vid from worcester showing how to fit flue rubber in a block of flats then pulling it back from outside and it was sealed

 

[GrahamM]

Just quickly reading flue instructions for Vaillant ecotec and Worcester cdi,although they mention a hole diameter for a core drill,they seem to suggest that only the rubber seals are needed as no mention of infilling the annulus so im guessing that an installer could not be criticized for not having done so ?

Don't recall the last MI's I read where it did mention sealing the annular space, but states it quite clearly in the BS.
Remember most of the MI's I have seen state "must comply with British Standards" etc

 

[Billy Bob Bob]

we are in the age of pushfit flue systems,some manf use self tappers,some dont,personally self tap them and cement around the annular space,that way that flues not coming apart and the unthinkable is not happening i dont really care how many mi,s say the flue tidys acceptable its just a tidy,your conscience and experience will tell you thats not enough do the job properly and cement and self tap,you can sleep at night knowing its safe ,if you dont care if its safe your in the wrong trade