If you are rebuilding the floor, then no better time to
beef up the for the weight of a mass inside your home. Your idea of an under floor mass fed from outside is just not practical. The Romans successfully used a floor heating system ... worked great ... unfortunately several slaves were tasked with feeding that fire all night long... A
RMH is best situated in the room everybody spends time in. It is easy to feed and the mass is right there to snuggle up to. A
RMH located elsewhere is a chore... will not be tended properly , will produce more
ash than normal and generally will lead to disillusionment with the whole idea ! Make your RMH part of your home ... treat it like a family member with caring and attention and you will LOVE your RMH and it will love you back, with drastically reduced
wood consumption, a tiny
carbon footprint compared to a regular
wood stove. Oh and never a chance of a chimney fire EVER!