Andy : A couple of links to help you help yourself :
https://permies.com/t/34193/tnk/permies-works-links-threads
https://permies.com/t/43625/introductions/Universal
Location : Look at Your Original Posters Name Space - and L@@K at mine !
( This will help make sure our answers reflect your location Climate )
Thermal mass + if the fireplace's other side is exposed to the outdoors then most of the heat
energy
stored in that mass will '' Leak out '' the low Temperature side ! Poor Efficiency. *
Is that a clean out in the face of your fireplace just below the mantle - or a shadow ?
You judgement of the skills you bring to the job and the time you can give to this re-fit will determine
where you go from here.
If a Rumford refit is not do-able with the time and materials then a wood stove will probably serve you
better- I have not priced a catalytic insert for a Wood stove in some years and the expected life of this
pricey unit should be carefully considered, Unless things have changed remarkably the guarantee on these
units depends on your ability to " Prove it failed during approved usage ''
A quick word about fire wood DRY !!! Depending on location Your Standing Dead wood
trees are drier than
anything else you can cut this year
Generally the goal is to cut More than one Winters supply - all
firewood should be cut early in the year, split,
stacked undercover, for use Not this Winter But next !
On re-reading this message is Not as upbeat as it might be but is honest and met from the heart !
For the Good of the Crafts ! Big AL
* Insulating and then boxing in the out door portions of your fireplace/chimney can help but may
have low priority at first ! A.L.