An open fireplace is ambiance; an insert is ambiance that actually works. For the handful of genuinely cold nights Dallas gets, an open masonry fireplace pulls more warm air out of the house than it puts in. A sealed insert flips that: controlled flame, real radiant heat, and — with a gas unit — instant fire at the push of a button, no wood to haul for two weeks of use a year.
The installation is a system, not a box: the insert is sized to your firebox, the liner or venting matched to the appliance and run the full flue height, and the surround finished clean. Gas installs coordinate licensed gas and electrical subcontractors for you — you're not chasing three trades, we are. Older Highland Park chimneys sometimes need masonry work before an insert goes in; if so, you get the repair quote in writing first, separately.