Gas fireplace venting for direct vent and B-vent units in Rio Grande Park

Sidewalks and driveways under the cap

People walk and park under sidewall caps more often than owners realize. One maker asks for 7 feet of clearance above a paved sidewalk or driveway on public property, and it rules out a cap directly above a paved sidewalk or driveway that sits between two single-family homes and serves both.

Our crew checks what sits below and in front of your cap, including side yards between houses, and writes down any location the chart does not allow.

Why a B-vent loses its draft

Poor draft has a long list of venting causes in one B-vent fireplace manual, and each one points at a different repair. Our pros work through it in order, since the fix for a short vent is nothing like the fix for a blocked one.

The list below comes from that manual. Several causes can exist on the same house, which is why we check them all before quoting.

• Too much offset or too many elbows
• A vent that is too short or too close to the roof line
• A blockage restricting the pipe
• The wrong vent type or the wrong size
• More than one appliance on one vent

Water inside the firebox after rain

Water in a gas fireplace usually came in from outside through the vent. The cap, the storm collar on a roof vent, the flashing and loose joints are the places our pros look first.

Wet controls need attention of their own. Manuals say a fireplace with any part that has been under water must not be used until a qualified technician inspects it and replaces the affected control parts. We check for that before we trace the leak.

A new roof around a vertical vent

Reroofing disturbs everything at a vertical gas vent, from the flashing to the storm collar to the cap. Section 503.6.7 of the Florida fuel gas code calls for gas vents to pass through a roof flashing, roof jack or roof thimble and end with a listed cap or listed roof assembly.

A generic cap from the roofing supply is not always the listed one. Our crew checks the cap, the collar and the height above the new roof surface and replaces what does not belong.

Direct-vent pipe that runs up through the roof

Vertical direct-vent runs have their own limits. One maker allows vertical installations up to 40 feet with at least 8 feet of vertical rise, and up to 10 feet of horizontal run within the system using no more than two 90 degree elbows.

Each 45 degree elbow on the horizontal plane cuts that 10 feet by 18 inches in the same manual. Our pros check the rise, the horizontal sections and the elbows they can reach, then the collar and cap on the roof.