Blocked isokern flue

[opo]

Hi, I've had a wood burning stove installed recently in a house with an existing chimney with a 6" isokern liner, but had problems with it not staying alight and smoke coming back into the room.
Tried sweeping it but couldn't get past about 5m up, which corresponds to the lower lead flashing tray.
Put a camera up there (photo below) and it seems the blockage is caused by the isokern liner being built on top of the flashing rather going through it, and the hole in the flashing being offset, so it's restricting the flue to about 4" at this point.
I've come up with 3 options for fixing it:
1. Demolish and rebuild the chimney (not good!)
2. Cut out the protruding lead in situ (not even sure this would be possible?)
3. Remove some bricks from the side of the chimney to access the liner (not sure this is feasible?)
Any thoughts, other options would be very welcome

 

[conny]

If the installer was HETAS certified he should have tested the efficiency of the system before signing it off as suitable for purpose.

You should get him back to sort it out as, once you start trying to repair it yourself, he will disclaim all responsibility.

 

[opo]

Thanks, yes, I'll be getting back to the installer, but I'm just trying to think ahead about what options they might have for fixing it. I'm also unclear who approves that the construction of a chimney that is built with the house is compliant, and where that approval is registered. I can't see any reference to the chimney at our address on the HETAS website, but I'm not sure whether I should or if it's all dealt with by building control and doesn't involve HETAS.

 

[lostinthelight]

Ive only built a few chimneys but have done them like yours with the exception of having the section above the lead line up and the inner edge of the lead dressed up inside the top section, done this way , any rain or condensates that run down get caught by the lead and drained through weep holes in the bricks .

 

[noseall]

If the installer was HETAS certified he should have tested the efficiency of the system before signing it off as suitable for purpose.

You should get him back to sort it out as, once you start trying to repair it yourself, he will disclaim all responsibility.

And what do you think the response will be to the customer from the HETAS guy? He will bounce it straight back to the customer and tell him he needs to pay for flue remedials - which the customer is going to have to do in any case.

 

[opo]

Ive only built a few chimneys but have done them like yours with the exception of having the section above the lead line up and the inner edge of the lead dressed up inside the top section, done this way , any rain or condensates that run down get caught by the lead and drained through weep holes in the bricks .

Thanks, that's interesting. I can see the logic in doing it that way and I suppose if the sections are lined up and the lead dressed properly the the impact on the flue diameter would be negligible. It would probably be ok if only they had lined up the lead properly.