To use cement only would be difficult, since it will simply start to spill over into the flue. It may not matter, but it will only allow you to fill up the flue with so thick of a material, since it has to “mound up”, no way to keep it flush with the inside of the flue.

What can you use to seal a boiler flue?

Quote from Youtube video: Do say we can use expanding foam as long as it doesn't crush the flue. System. And it's flame retardant or heat resistant. We could also use silicone as well.

Should boiler flue be cemented?

The flue should be properly sealed on both sides

It should be sealed using sand cement or equivalent material. It must be sealed properly so no exhaust fumes can come through into the building.

How do you fill a boiler flue?

Quote from the video:
Quote from Youtube video: Up. Now hopefully dawn on up a video on easy fill 20 it's one of the best films you can actually get it's so easy to use it dries quickly and is very easy to send afterwards.

Can you use expanding foam around a boiler flue?

It should be ensured in all installations that the wall is sealed to the flue inside the property by using expandable foam, by pointing with sand and cement or using any other suitable material.

Can you seal a boiler flue with silicone?

If during installation Gas Safe registered engineers are unable confirm the suitability a sealant, e.g. an expanding foam product or silicone, from both the boiler and sealant manufacturers then the sealant product should not be used.

Should a flue be sealed?

The flue must be sealed to the inner surface of the wall and the outer rubber flue sealing ring must be fitted. The rubber sealing ring provided for the outer surface is deemed an adequate weather seal to a flat, smooth surface.

What do you use to seal the flue pipe?

To air seal around combustion flues, use fire-rated caulk and UL-rated collars or sheet metal cut to fit and sealed with fire-rated caulk, while maintaining proper clearance between flue and combustible materials.

Is expanding foam fire retardant?

Fire rated expanding foam can be used as an efficient seal against smoke and gas, providing up to 240 minutes fire rating.

Does expanding foam react with copper pipes?

Moisture curing, polyurethane expanding foam, specifically developed for filling gaps around pipes and other plumbing applications. Adheres to most sanitary and plumbing materials; PVC, CPVC, copper, cast iron, chromed copper and chromed brass. Resistant to water, heat and ageing.

Can expanding foam be used around heating pipes?

Don’t use spray foam such as Great Stuff around heat sources: it will melt and produce toxic fumes. BTW, the reason the holes are so big is probably because there used to be three-inch pipes there.

How do you fill gaps around heating pipes?

Quote from the video:
Quote from Youtube video: Some ground cover and of course safety glasses great stuff is very sticky. So make sure that you roll down your sleeves. And cover your arms.

How do you fill holes in copper pipes?

You can use Flex Seal, expanding foam, or silicone sealant to fill and seal the gaps and cracks around your copper pipes. These products will effectively fill up the space in between your pipes and walls to ensure that no water, air, moisture, and small insects can get in.

What is the best sealant for copper pipes?

Copper repair epoxy putties provide one of the easiest ways to fix a leaking pipe. Epoxy putties consist of two components, a resin and a hardener. When mixed together, these components form a material that can be used to plug holes before setting into a hardened material.

Is expanding foam corrosive to copper?

It certainly won’t cause any issues with the copper, so don’t worry about that. Possibly the heat from the hot pipe will degrade the (some) foam immediately in contact with it, but actually I think even that is very unlikely. (A hot ‘cylinder’ is effectively a big copper tank covered in exp foam!)