Gas fireplace venting in Plymouth

The restrictor at the flue outlet

Some direct-vent installations call for a restrictor where the vent leaves the fireplace. In one maker's manual, a top-vent unit whose first piece is a 90 degree elbow toward a sidewall needs an open-center restrictor made by breaking the center rib out of the supplied part.

A restrictor that is missing, or of the wrong style for the layout, changes how the fire draws. Our technicians check which restrictor your manual calls for, whether it is in place and whether it matches the route the pipe actually takes.

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 spill switch on a natural-vent unit

One B-vent fireplace manual shows a spill switch in the control wiring. Spill switches are safety devices mounted at the draft hood to detect exhaust spilling out because of a blocked vent or poor draft, and they shut the burner down when it happens.

One maker of these switches says that after a shutdown, the cause has to be found and corrected before the switch is reset. Our pros never bypass one. They look for the blockage, the short vent or the negative pressure behind it and quote the repair that removes the cause.

A natural-vent fireplace that shuts down early

When a B-vent unit runs for a while and then shuts itself off, one maker's troubleshooting table points to a blockage or restriction in the venting. The fix it gives is to remove the blockage and relight the pilot following the lighting instructions.

Finding that blockage is the real work. Our crew checks the cap, the reachable pipe and any enclosure around the top, and if nothing turns up there, the draft checks and the controls come next.

What the written venting estimate lists

Our estimate breaks the vent job into the pieces you would want to see. Parts come by name, access openings and finish repairs sit on their own lines, and anything we could not reach is stated plainly.

Your approved price holds unless you sign off on added work. Nothing is hidden, and booking within 72 hours after the inspection puts 10% off on that same page.

• Listed vent parts for your model
• Wall, ceiling or roof access
• Finish repairs after access
• Test burn and leak check