Combustible materials around boiler

[KPaul]

Hey guys. Had a boiler conversion last week and now have a Worcester Bosch Greenstar 4000 combi boiler. Got a quick question about the old flue hole that's left behind by the gas engineer. It's been roughly bricked up internally but we still have cavity wall insulation dropping down. I noticed that he packed around the bottom of the new flue with kitchen roll and I also noticed he'd left a piece of cardboard behind the new boiler which was put on the wall overnight to stop draughts. I've removed the kitchen roll and will get the engineer back to fill the gap with something more suitable but before I ask him about the cardboard I just want to see if it's against any regulations and needs to be removed, or is the boiler so well sealed that's it's simply not an issue? Just looking for a second opinion before I approach him about it.

Thanks, Paul.

 

[polesapart]

Not an issue. The outer section of the concentric flue is the air inlet duct.

In any case flue temperature on a condensing boiler is so low that inner section through which the exhaust gasses pass is made of plastic.

 

[KPaul]

@polesapart Thanks mate. And the cardboard behind the jig of the boiler? Is that okay too?

 

[KPaul]

Sorry I can see that you meant the cardboard isn't an issue as I've already removed the kitchen roll!

What's best to use to fill the gap around the flue? Fire rated expanding foam?

 

[polesapart]

.

 

[Elkato531]

What's best to use to fill the gap around the flue? Fire rated expanding foam?

Your installer should have done this. Get him back to finish the job.

 

[KPaul]

I've sent a message so I'll see what he says. The priority was to ensure he hasn't left the boiler in a compromised state with the cardboard, etc. first.

 

[Madrab]

so I'll see what he says.

It's not really about what he says, he (edit) shouldn't be leaving the flue space unsealed and he needs to finish it. Part of the Job.

 

[Murdochcat]

Don't pay his invoice until hes finished the job

 

[CBW]

What's best to use to fill the gap around the flue? Fire rated expanding foam?

I find sand/cement, quickset cement, or polyfilla is best.

 

[Madrab]

What's best to use to fill the gap around the flue?

Internal - external?

 

[KPaul]

Internal - external?

External is totally bricked up so no issues there. The inside is bricked up too, but the cavity wall insulation (polystyrene balls) are still finding their way out somehow and onto the kitchen counter. Just need the inner skin patched with something to stop this happening (and preferably not kitchen roll).

 

[KPaul]

Don't pay his invoice until hes finished the job

It's through Boxt so already paid for.

 

[KPaul]

It's not really about what he says, he (edit) shouldn't be leaving the flue space unsealed and he needs to finish it. Part of the Job.

I've raised it with Boxt who are assessing it based on photos I've submitted. They'll have him back out to sort it out I'm sure.