I am interested in installing a drolet 1800 insert in my masonry fireplace . I currently have an Ashley hearth 1820E. After looking at clearances for the drolet it states that it should be 27 inch min from stove top to mantle. In my fireplace with the drolet it would be 22 in and I inquired with the manufacturer about installing a heat shield with air gap under the mantle and drolet said it wouldn’t matter had to be 27 in. For those that have the drolet 1800 are there any other suggestions besides a non combustible mantle or for those that have a shield how’s it working out ? Thanks in advance