Gas fireplace venting by local pros in Conway

How a B-vent fireplace uses the air in your room

A natural-vent, or B-vent, fireplace burns air from the room and lets the warm exhaust rise through its own pipe by draft. The unit has a draft hood, and one maker requires that hood to sit in the same air pressure zone as the combustion air inlet.

The pipe must be Type B gas vent listed to UL 441, which the Florida fuel gas code requires in section 503.6.1. Our technicians confirm the pipe type from the markings on the sections they can reach, since the wrong vent type is one of the causes of poor draft listed in the manual.

Flex pipe secured at both ends

Flexible vent pipe is only as good as its connections. One maker wants the flex to overlap the fireplace and termination collars by at least 1 inch, or 1 inch past an internal bead, and to be held with a hose clamp.

The same manual asks the installer to tug the pipe to prove it will not slip off, and to repeat the process on both the inner and the outer pipe. Our technicians check each clamp they can reach and redo any connection that pulls loose.

• Overlap of at least 1 inch on each collar
• A hose clamp on every flex connection
• A pull test on inner and outer pipe

Offsets and horizontal runs in B-vent

Natural draft needs the pipe to keep climbing. One B-vent fireplace manual keeps every horizontal run shorter than half the total vent height, measuring pipe center to pipe center, and wants each run to rise at least 1/4 inch per foot, never level and never downhill.

Too much offset is also the first cause in that manual's list for poor draft. Our pros check the slope of every horizontal section they can reach and compare the total offset with the height of the whole vent.

Supports that keep weight off the elbows

Vent pipe should hang from its supports and never from its joints. One B-vent fireplace manual wants a hanger on horizontal runs at least every 5 feet, and offsets held up in a way that keeps the pipe's weight off the elbows.

Sagging pipe pulls joints apart and ruins the upward slope the draft depends on. When our crew finds a missing hanger or a bent strap, it goes into the estimate along with the section of pipe it supports.

Looking inside a framed chase

A framed chase hides the vent between the fireplace and the roof. Some have an access panel, and many do not. One B-vent fireplace manual asks for the chase to be insulated like an outside wall while keeping clearances to the pipe.

Our crew checks whatever the chase lets us reach and states what it could not see. If opening the chase is the only way to settle a question about the vent, the estimate shows the access and the patch as their own lines.