suitable materials for filling gap around flue

[Backboiler]

WHAT!!!
really :angelsad2:

i must be over charging, i normally make that into an hours work and hand out a £70 bill plus parking

Yeah. It take 10 mins max. That probably why I do loads of Landlord checks

 

[neily01]

thanks for that, sounds like its worth having a tub in the van

 

[Mickyplumb]

As someone said, expanding foam but need to make sure it's the fire stop type

 

[gasmanrob]

if your using expanding foam make sure the boilers turned off!

A bloke in sidcup was told his boiler wasn't up to standards last year as his flue was not sealed through the void, so being a builder he thought i know ill whack some expanding foam in that. boiler fired up as he was squirting it in, the fumes from it got sucked in the intake and blew the boiler to bits case and combustion box. (was a profile) and the fella suffered 3rd degree burn as the can blew up in his hands.

Wouldn't use it myself been to a few jobs where someone had put to much in and as a result it squeezed on the flue causing it to crush a little and pull it out of its seal. why risk that for the sake of a bit of sand and cement. i keep a mortar gun on the van so if i cant get a trowel in a can load that up and pretty much inject it in.

 

[mfgs]

Bag of ready mix ,

I have always got a bag of ready mix in the van.

 

[AWheating]

does it say on expanding foam tubes it will have no reaction with metals and plastics?

 

[Barry98]

I can't see the point of foam your still going to need some cement outside for blow off , condensate if outside , flue if no collar so why not not mix a bit extra

 

[GrahamM]

I can't see the point of foam your still going to need some cement outside for blow off , condensate if outside , flue if no collar so why not not mix a bit extra

Exactly. And it is fireproof, weather proof, little shrinkage, cheap and only 5 mins to mix and apply.
Why would you use anything else?

 

[wheeto]

flue if no collar

I thought it was collar or no collar nowadays? ie it has to be sealed even if there's a plastic collar hiding the gap?

Or I may just have misunderstood you.

 

[Barry98]

I've always sealed it even with a collar to be honest I didn't know you couldn't , what I meant was evn if under the collar you use foam you still need cement to do prv condensate etc

 

[GrahamM]

Unless the manufacturer specifically says it is not required, to comply with BS5440 for room sealed appliance:
'The annular space between the flue assembly and surrounding structure shall be sealed.'

The collar is does a decorative item and does not give any support to the flue through the wall or seal the annulus as above.

Here is another way I look at it. The flue term must be 300mm from a ventilation opening. Is the flue hole not an opening?

 

[Pssst]

Havent read it all.

Unsealed flues are, IMHO at least AR.

It is not uncommon if the wind changes,for POC and/or unburned gas or gas /air mixes to re-enter the premises.

Many installers just slip the rubber flange over the outside but that isnt good enough. They do deform with weather,dont always seal well and can fall off.

 

[Backboiler]

I thought it was collar or no collar nowadays? ie it has to be sealed even if there's a plastic collar hiding the gap?

Or I may just have misunderstood you.

I remember on my inspection by GSR we went to a boiler I had installed. While doing a tightness test the inspector asked if I had sealed under the collar of the flue/chimney. "Of course I have" I replied and left it at that. I went inside the property for my LDF, when I returned to the meter the inspector was standing on a stool inspecting under the flue collar. He looked at me and said "just checking,well done"

 

[Pssst]

And did you then admonish him for not using a suitable means of access for inspection i.e a stool instead of a step ladder?

 

[Backboiler]

And did you then admonish him for not using a suitable means of access for inspection i.e a stool instead of a step ladder?

Sorry but I wondered if any bright spark would pick up on that. In fact it was my aluminum folding platform steps but it was easier to spell stool

 

[Billy Bob Bob]

right first of all if its unsealed its AR in particular push fit plastic flues commonly found on HE appliances if its not made good whats to stop that flue coming out of that bend if a fault develops such as explosive ignition?it has happened before and caused fatality's,not all will have a self tapper holding them together,secondly normal expanding foam is not deemed suitable,it must be the heat resistant type,thirdly how hard is it to carry sand and cement on the van?? if you find it not sealed sort it out and charge accordingly you are the last person there,the buck stops with you,thats no grey area thats black and white

 

[Dannypipe]

I carry a tub of fire cement. It's ready mixed and is under a fiver a tub. Plus it doesn't go off in the tub, but once applied it goes bullet hard within a few hours. I use gloves when squiding it in, and then trowel it off with a pointing trowel. Doesn't take long.

You can buy it from Screwfix for about £4.

 

[buckley plumb]

How to install a flue for a Greenstar boiler - YouTube

 

[Barry98]

No Nonsense Fire Cement 2kg | NoLinkingToThis

How many flues can you seal with a tub of that

 

[Dannypipe]

No Nonsense Fire Cement 2kg | NoLinkingToThis

How many flues can you seal with a tub of that

Yeah, that's exactly what I was talking about. I guessed the cost as I couldn't remember. You can do loads of flues with a tub like that. It lasts ages in the tub, and as I said, goes rock hard once set. Which by the way isn't that long.