After some measured success in building a RMH (much thanks to this forum) , I am taking on an old boxy fireplace. It never drew very well, despite having a good flue and smoke chamber, so I am thinking converting it to the Rumford dimensions (following the specs from Rumford.com). But, in typical fasion, I have no idea what I am doing! I know that Erica and Ernie mentioned that it can be done. But, I don't want to do a huge messy rebuid. My idea is to mortar up fire brick using fireclay/sharp sand and hand plastering a "throat" using metal lath and natural plaster.
But has anyone done it?
Any ideas what I should use for plaster for the "throat shape"?