Gas fireplace venting done by the manual in University

Reading the rating plate before touching the vent

Every gas fireplace carries a rating plate with its model, its gas type and its input. That plate is the key to the right manual, and the manual is the key to the vent. Without it, nobody can say which pipe, cap or restrictor belongs on the unit.

On the first visit our crew finds the plate and copies the model, gas type and input into your service record. If the plate is missing or unreadable, we say so in writing and explain what that means for any repair we quote.

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

The glass door is part of the vent system

On a direct-vent fireplace, the glass door closes the sealed chamber the vent serves. One maker cautions that a door not properly seated and sealed can leak combustion products, and it forbids running the fireplace with the door off, cracked or broken.

The same manual says replacement glass door assemblies must come from the fireplace maker, with no substitute materials. Our technicians check the latches, the gasket and the seating of the door whenever they inspect the vent.

Snorkel terminations on low walls

When a fireplace sits low and the cap has to clear the ground, some makers use a snorkel that rises along the outside wall. One manual requires at least 24 inches of vertical rise for its snorkel and limits the horizontal run to 36 inches with that rise.

The same manual asks for a watertight seal where the pipe passes through the wall and at least 4 inches between the snorkel and any soil. Our technicians check the seal, the soil line and the cap on every snorkel they inspect.

Testing the fireplace after vent work

A vent repair is finished only when the fireplace runs well on it. After the work, our technicians light the unit, watch the flame against the manual's description and let it run long enough to see a steady burn and a normal shutdown.

Any gas connection that was disturbed is leak tested with a soap solution or an approved leak test spray, as manuals direct, and never with an open flame. You see the fireplace running before we leave.