Connector against chimney
Stove pipe, whether single or double wall, connects the stove to the chimney, and it stays in the room you can see. The chimney starts at the ceiling or wall and runs outside. Mixing up the two is one of the most dangerous mistakes in a stove install.
What HT adds
UL 103 applies to factory-built chimneys for residential appliances. The HT version adds a test at 2,100 °F for 10 minutes, a stand-in for a chimney fire. Chimneys that claim it must be marked. Under NFPA 211 as commonly quoted, chimneys serving solid-fuel appliances in a dwelling need the HT rating.
How to read a listing
Search the listing for “UL 103 HT” or for an equivalent mark. Be careful with listings that call a part “chimney pipe” without any standard. Chimney brands are also rarely interchangeable, so one maker’s elbow often will not lock into another’s section.
What we do here
Our stove pipe, elbow and thimble reviews say whether the listing states a rating. We do not say an assembly is acceptable; that belongs to the maker’s installation manual and your local inspector.
Questions that keep arriving by post
Is double-wall stove pipe the same as Class A chimney?
No. Double-wall connector reduces the clearance inside the room, but it is still connector. Where the flue passes through a ceiling, wall or attic you need a listed chimney system with its own support and pass-through parts.
What does Class A mean?
It is the trade name for a factory-built chimney rated for solid fuel. Look for UL 103 HT in the listing, and do not rely on the phrase alone.
Last reviewed November 1, 2026