From a Valued Customer:

Can the EB2400 Black Bio Ethanol Fireplace Insert unit be placed in an existing fireplace?

Yes. The EB2400 Black Bio Ethanol Fireplace Insert may be used to convert an existing fireplace. As you had mentioned, it may simply be placed in the interior of an existing non-combustible hearth. It is important to ensure that the floor on which the burner is placed is level for safe use. For best performance, we also suggest that the flue be sealed or closed, as additional oxygen will increase operating costs. This burner insert is also made available with a steel grate surround, which is ideal (if space allows) for converting existing fireplaces. This model may be found in our Fireplace Grates Category – Model EBG2400 Fireplace Grate.