Check recess size and ventilation before building the surround. Fireplaces and flame-effect solutions for interiors, including built-in, wall-mounted and decorative formats. Check overall and recess dimensions, power supply, ventilation and maintenance access before designing the installation. Heat output varies by technology and must be confirmed for each model. A decorative flame effect may have different requirements from a unit also intended to heat. For an insert, establish the recess only after reviewing the drawing and fitting instructions for the chosen model.