Gas fireplace venting for direct vent and B-vent units in Bryn Mawr

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

Type B pipe, listed for gas

B-vent is double-wall pipe made for gas appliances with draft hoods. Section 503.6.1 of Florida's fuel gas code calls for Type B and BW pipe listed under UL 441, and one fireplace manual insists on Type B pipe carrying a listing from a nationally recognized testing agency.

The same manual sizes the vent by model, 4 inch pipe for one and 6 inch for others. Pipe that is too large or too small shows up in that manual's poor-draft troubleshooting, so our pros check the size as well as the type.

Outside combustion air for a B-vent unit

Some B-vent fireplaces can take their combustion air from outdoors through a kit, which one maker calls optional unless building codes require it. The same manual asks for short duct runs with few turns and an outdoor inlet that cannot be blocked by accident.

It also says never to take combustion air from an attic or a garage, where fumes could be drawn into the fireplace. Our technicians check where your air kit draws from and whether its inlet is still open.

Replacing one damaged section

When only one section of pipe is damaged, the repair still starts with the sections around it. Our technicians identify the damaged piece, the adjoining components that will stay and the maker of each.

If the sections on either side are concealed, we explain the access needed to reach them and what it costs. Replacing one visible fitting does not prove the rest of the run is sound, and the estimate says clearly which parts we saw and which we did not.

A gas odor at the fireplace

Gas fireplace manuals list the same steps for a gas smell. Leave every appliance unlit, leave light switches alone and do not use a phone inside. Get out of the house at once and call the gas utility from outside or from a neighbor's phone, and call 911 or the fire department if the utility cannot be reached.

Nobody should go looking for the leak. Once the utility or the fire department says the house is safe, the fireplace stays off until a technician has found and repaired the cause.