Guide ยท Liner specification
316 or 904 stainless liner: what should decide the specification?
Neither 316 nor 904 should be chosen from grade alone. The installer needs to match the liner and complete chimney system to the appliance, permitted fuel, temperature and condensate conditions, expected use and manufacturer requirements.
Updated 22 August 2026
The grade describes material, not the entire system
316 and 904 are stainless-steel families used in flexible liners. A higher alloy specification may offer greater resistance in some conditions, but that does not make every product with that number interchangeable or suitable for every stove.
The product designation, tested classification, diameter, installation method, connections and warranty conditions all matter. The proposed liner should be identified as part of a compatible declared system.
Fuel and use change the exposure
Combustion products and condensation can be corrosive. The fuels permitted by the appliance, how the stove is operated, the chimney environment and the frequency of use affect the duty the liner faces.
That is why simple claims such as one grade being for wood and the other being for multi-fuel are incomplete. The installer should use the liner manufacturer technical information and the appliance instructions for the actual proposal.
Installation quality remains critical
A premium material does not compensate for an incorrect diameter, damaged liner, unsuitable connection or an unresolved chimney defect. The route also needs to be serviceable, protected as required and finished with compatible components.
Ask what is included above and below the flexible section, how the chimney has been assessed and what records you will receive. Those answers tell you more than grade alone.
Use a written, property-specific recommendation
The quotation should name the proposed system and explain the main reason for the selection. It should not promise a universal lifespan, because use, fuel, moisture, sweeping, maintenance and manufacturer warranty terms differ.
The Fireplace and Stove specifies flue work after inspecting the property and confirming the intended appliance. That keeps the grade discussion attached to the chimney system it will actually form.
Common questions
Is 904 always the correct upgrade?
No universal rule makes it necessary or suitable in every case. The whole product classification, fuel, appliance, use and chimney conditions need to support the choice.
Can I compare two liners by price and steel grade?
That comparison is incomplete. Include diameter, declared performance, system components, installation method, warranty conditions and the evidence used to specify it.
Does a liner grade determine its lifespan?
Grade contributes, but service life also depends on fuel, operation, condensation, installation, sweeping and maintenance. Avoid any unconditional lifespan promise.
Who should select the liner?
A competent installer should specify a compatible system using the property assessment, appliance instructions and liner manufacturer information.
Turn the research into a property-specific plan
Bring your questions to the Lichfield showroom, or ask us to assess the room, chimney and proposed appliance at home before anything is ordered.
Ask about a home surveyMore guides
Read next
What should you budget for a wood burner installation?
A clearer way to compare stove quotations without relying on a misleading headline figure.
Read the guideDoes your stove installation need a chimney liner?
Why lining is a survey decision rather than an automatic addition to every stove installation.
Read the guideCan a wood burner be fitted without a masonry chimney?
What is involved in designing an insulated chimney system for a home with no suitable chimney.
Read the guide