Draw the room, then draw the glass
Mark a direction arrow for the viewer standing in the room. Label the front viewing pane, the glazed return and the solid return separately. Add the door to the room, the hearth edge and a fixed feature that will still be there when the framing is open. The manufacturer drawing, not your choice of left or right terminology, should determine which configuration appears on the purchase order.
Compare the product's real configurations
A purpose-built corner unit is different from a see-through appliance viewed in two opposite rooms or a bay unit with glass on three sides. Heat & Glo's corner products and the Stellar corner series illustrate how manufacturers document actual configurations. Ask for the sheet for the exact size and orientation, including control or service access and vent location. Rotating another unit may move the wrong face or an essential connection against a wall.
Check the sightline that justified the second pane
On a print of the floor plan, draw a line from the dining chair or entryway to the return glass. Mark cabinetry, a projecting wall or a deep trim piece that could conceal the view. Ask the installer to confirm the approved framing and finish before the plan goes to the cabinetmaker. Store the accepted plan with the model suffix clearly visible.