I have a 35 foot brick chimney in an old house.

[dvs14]

Do I really need to insulate my 6 inch liner. Seems like If I clean it periodically, I don't need to insulate

 

[branchburner]

You only need to insulate it if there is a safety/code issue. Does the chimney have a clay tile liner that is in good shape (without cracks or damage) top to bottom?

 

[begreen]

If this is an old house with an original fireplace and chimney that is not clay lined it will need to be insulated by code. The liner insulation has nothing to do with cleaning. The insulation is to stop heat transmission from the liner through to the surrounding brick and wood framing. If this is an original flue, the mortar in some places is probably like dust by now.

The flue must be thoroughly cleaned before installing the liner. At 35', it will likely draft very strong. This is a case where restricting it a bit may be necessary. It could be that stepping down a size in pipe would be a good choice for this tall a chimney.

 

[savageactor7]

Almost identical to our situation a few years ago.

The chimney was rebuilt with flu brick some years earlier and it sat in the center of the house. 2 installers inspected it and said a liner wasn't necessary.

 

[begreen]

We'll need to know whether the flue is clay-lined and if it is, the tile size + what is being connected to this tall sucker.