Your local gas fireplace venting team in Lockhart

Why horizontal flex vent rises away from the unit

Flexible and rigid pipe follow different installation rules in one maker's manual. Horizontal twist-lock pipe in that manual is laid on a level plane, while horizontal flex has to climb 1 inch for every 24 inches as it leaves the fireplace.

A flex run that sags between supports loses that rise. When we find a sag in a reachable section, our technicians support it again at the right slope and note the change, since the manual's numbers only work if the pipe actually follows them.

Insulation counts as a combustible

It surprises many owners, but one B-vent fireplace manual tells installers to treat insulation as a combustible material and to keep the required clearances to it. The same manual asks for a chase to be insulated like the outside walls of the house.

Those two rules work together. The chase gets insulated, and the vent inside it keeps its air space. When our technicians open an access point, they check both and write down whether the insulation has drifted against the pipe.

Room to breathe in front of the cap

A sealed fireplace pulls its combustion air in at the cap, so the space in front of the cap matters. One direct-vent manual keeps a 24 inch zone in front of the termination hood free of shrubs, garden sheds, fences, decks and utility buildings.

Yards change. A hedge fills in, a shed gets delivered, a gate goes in. Our crew measures that 24 inch zone on every sidewall vent and tells you exactly what has to move.

• Bushes and hedges
• Garden sheds and utility buildings
• Fences and gates
• Decks built after the fireplace

Fastening B-vent without piercing the liner

B-vent has an inner liner that carries the exhaust, and screws through it create leaks. One fireplace manual forbids driving sheet metal screws through that liner and fastens the first section to the fireplace with self-tapping screws and a band of plumber's strap instead.

The same manual explains how the first section fits the appliance collar, which differs between the 4 inch and 6 inch models. Our technicians check that first connection closely, since it carries the whole run above it.

Aluminum liners that need checking later

Flexible aluminum liners are light and easy to install, and they need watching. One maker's co-linear instructions say aluminum venting should be professionally inspected periodically for corrosion and damage and replaced when necessary.

If the installation will not allow future inspection or replacement, the same instructions call for stainless steel liners instead. Our pros ask that question at the planning stage in Lockhart, so the liner you pay for suits the access your chimney actually offers.