Flue cores

[stratplus]

What size cores do you use for the boiler flues, 117 or 127mm?

 

[woodytheplumber]

usually 127 then fire foam and sand and cement from outside

 

[GasmanxxxR1]

127mm

 

[GasmanxxxR1]

I dont use foam, bit of loft lagging etc then sand and cement/plaster

 

[buckley plumb]

127mm

 

[stratplus]

Isn't expanding foam frowned upon now, from reading another post yesterday??

 

[woodytheplumber]

I have allways used fire foam when working with others so use it now im on my own I remember about a year ago a gas safe inspector came onto our job as my mate was foaming the flue he didn't say anything about it whats so ever, the inspector even watched him foam It while waiting to talk to him

 

[stratplus]

Is this fire foam standard expanding foam?

 

[woodytheplumber]

I have always used fire foam it goes in a standard foam gun though http://www.NoLinkingToThis/p/no-nonsense-fire-rated-expanding-foam-gun-grade-750ml/90589

 

[bigads28]

Using fire foam is ok, but you need to know it's fire foam and that's where the issue comes. If woody fits his foam and then I service it next year I don't know that it's fire foam. Apparantly a very few foams give off harmful fumes when they are heated.

 

[woodytheplumber]

fire foam in pink in colour surely that's done for identification ? that's my thinking anyway

 

[bigads28]

fire foam in pink in colour surely that's done for identification ? that's my thinking anyway

Very true woody, the powers change or apply these updates don't really apply much logic to them sometimes. It's not like a condensing flue gets hot these days is it!

 

[stratplus]

What about using fire cement?

 

[Ermintrude]

Why on earth fire cement?

 

[lame plumber]

in case it gets too hot lol

 

[stratplus]

Fire cement is what the builder wanted to use.

 

[stratplus]

Whats wrong with using mortar anyway?

 

[AWheating]

sand and cement is fine for those who arnt lazy 🙂

 

[woodytheplumber]

I allways sand and cement them in after the foam its the easier way to pack them out so the mortar doesn't just crumble away for having nothing to rest against inmy opinion

 

[ed209]

In the old day woody them Victorians would have packed there flue holes out with newspaper or horse hair/poo, non of that foam rubbish, then made good with a lime mortar

 

[Ermintrude]

Yeh back when I were a lad we stuffed in the old template and bits of kitchen roll

 

[goz666]

I was with a mate last year who was having his inspection by GS, he took them to a job we'd done on a Vaillant install. Sand n cement, inside and outside both covers fitted.

GS bloke pointed out that we hadn't put the three screws in the internal white flue cover, I said it's been stuck back with a bit of silicone to keep it in place, he said ''If there are screw holes in the cover, then screws must be inserted and screwed into the wall' I was a bit gobsmacked tbh considering some of the sh1te I drive past every week.

Edited to add : I always core 5" btw.

 

[ed209]

You also screw in to the flue

 

[ed209]

Well your supposed to I never have but
Might start belt and braces