Oil to gas, the northern New Jersey driver
This part of the state has a large stock of houses that were built with, or converted to, oil heat and have since moved to gas. A conversion changes everything about what the chimney is being asked to do: a different flue gas, a different temperature, a different volume. It is one of the named triggers for a level 2 inspection under NFPA 211, and it is the point at which a flue that suited the old appliance stops being adequate. The heating contractor usually raises it, and the answer belongs before the new appliance is fitted.
Why a stainless liner instead of a repair
A clay tile flue is a stack of separate pieces inside a masonry shaft, and there is no practical access to any of them except from the two ends. A stainless liner is one continuous pipe run down that shaft, sized to the appliance, so the fault is bypassed rather than patched. Where the installation calls for it, insulation is wrapped around the liner, which keeps the flue gas warmer on the way up and reduces the condensation that damaged the original.
Sizing is the part that goes wrong
A liner that is too large behaves like the oversized flue it replaced, and one that is too small starves the appliance. The size comes from the appliance, its output and the height of the chimney, and it is taken from the appliance data and not from what fits neatly down the shaft. No sizing figure is published for this work, because a number printed for a category is worse than no number at all when the specific appliance is what sets it.
The New Jersey verification form
New Jersey has its own document for this. The Uniform Construction Code chimney verification form, UCC-F370, is filed with the permit when a fuel fired appliance is replaced or converted, for example oil to gas. It records the liner manufacturer, model, listing, material and size and the chimney height, and it is signed by the verifying individual or company, not by the homeowner. A town asks for it with the permit application or before the final inspection, and a homeowner cannot submit it in place of the inspection the code requires.
What the top of a new liner has to do
A liner changes the top of the chimney. It has to be terminated and sealed so that rain cannot run down between the new liner and the old flue, which is a space that had no reason to exist before. A top plate and a cap are part of the installation rather than an extra, and the crown around them is checked at the same time, because a liner installed under a cracked crown is a new pipe inside a wet chimney.
How this job is arranged here
The inspection comes first and produces the camera evidence, the sizing and the scope in writing. The work is then scheduled with the team against that scope. Nothing is quoted before the scan.