Gap around Combi flue

[Irie]

We have a combi boiler (Potterton Performa 24) with quite a gap around the flue on one side. This lets air in from outside (and insulation when we had the Cavity wall done!) so ideally I would like to patch it up somehow.

Here is a picture of the problem:

Untitled

• Irie
• 3 Aug 2012
• 1

Can anyone suggest a good way of covering this?

 

[Agile]

Internally plaster or good filler mixed from powder.

Outside cement!

Tony

 

[Irie]

Cheers, from what I can tell outside is pretty good. Any good filler recommendations? I have some Polyfilla, I think it's the deep gap stuff.

 

[nickmatt1]

Cheers, from what I can tell outside is pretty good. Any good filler recommendations? I have some Polyfilla, I think it's the deep gap stuff.

What boiler is it? The flue appears to go downwards to outside. If it is a condensing boiler it should rise to outside

 

[Irie]

Its a Potterton Performa 24. In reality the pipe looks pretty straight to me, I think it is just the camera angle.

 

[Boilerman2]

I initially thought there was a big problem with the flue angle, until i blew up the pic, it looks ok then - so as said just a strange camera angle

 

[nickmatt1]

Ok.there should be a flexible seal on the outside, and the inside can either be sealed by plaster, or another seal similar to that outsde.Outside normally black, inside white. I prefer to use seals both sides, as it makes any servicing issues easier to solve..like removing bees'nests, bird nests, etcYou would be surprised at what I have found in flues!

 

[Irie]

Awesome thanks! Are the seals normally a spare part for the boiler or just buy from a merchant as i am not quite sure what I should be looking for.

 

[nickmatt1]

usually spplied with flue, but can be purchased at local plumbers merchant

 

[gaswizzard]

Ok.there should be a flexible seal on the outside, and the inside can either be sealed by plaster, or another seal similar to that outsde.Outside normally black, inside white. I prefer to use seals both sides, as it makes any servicing issues easier to solve..like removing bees'nests, bird nests, etcYou would be surprised at what I have found in flues!

If the flue were made good on both sides then 'bee's nests' and 'birds nests' wouldn't be an issue would it.

 

[Whitespirit66]

Cheers, from what I can tell outside is pretty good. Any good filler recommendations? I have some Polyfilla, I think it's the deep gap stuff.

That'll do. Looks like a deep crack to me.

 

[Agile]

Be aware that Nickmatt's advice does not agree with the views of Gas Safe inspectors who do NOT agree that the rubber gaskets are adequate.

They expect both outside and inside should be hard sealed!

 

[nickmatt1]

Be aware that Nickmatt's advice does not agree with the views of Gas Safe inspectors who do NOT agree that the rubber gaskets are adequate.

They expect both outside and inside should be hard sealed!

,

That is interesting. After consulting with several boiler manufacturers, this matter was raised after an inspector picked up one of my installations. The manufacturers decided that my installation was correctly installed, and that it conformed to their specifications. Gassafe sent out a bulletin to all engineers about the installation and amended the previous manufacturers' instructions about extending flues through walls. Perhaps what I failed to point out is that the gap around the flue should be sealed sufficiently to support the flue, and that the rubber seal should provide adequate seal around the flue and opening

 

[Agile]

The manufacturers ( mostly ) are happy with the rubber gaskets as a seal to the wall. On pebble dash they dont make a good gas seal.

Gas Safe Inspectors however expect the flue to be hard sealed on the outside and really on the inside as well.

Quite part from their view, its my opinion that it needs to be hard sealed on the outside ( with cement ) as part of the weather proofing of the building.

The question arose in respect of one of my installations. It was correctly hard sealed on the outside but only with a gasket on the inside. The Inspector complained that it needed to be hard sealed on the inside as well ( normally with plaster ).

As I did several warrantee visits for manufacturers it is important that I can remove the flue elbow from the top of boiler. That can often be done if not sealed on the inside.

I dont like to create arguments with G-S Inspectors and I expressed my view that it is better for maintenance access if the inside is NOT hard sealed. He saw my point and we left it at that with me agreeing with him that it would be better sealed on the inside as well but taking maintenance requirements into account I do not want to hard seal my installations.

Tony

 

[nickmatt1]

I agree about the pebbledash, the only way to solve the problem there is to use a gas seal Rubber tape around the exterior aperture thus sealing the hole effectively. This is in addition to the flexible seal. This provides adequate weather proofing as well as denying any products of combustion re-entering the premises, whilst allowing removal of flue for servicing/maintenance purposes.