Thank you.   

I’ve set up a little circulating fan across the hot brick.   Limited success so far… 

A stone/ceramic heat sink could be so cool if it were portable.   I’ll keep trying. 

 my next heater will be a rocket mass heater. but for now, capturing and storing as much heat as possible from the fire is the way. 

 A free standing wood stove doesn’t require a whole lot. However, In-wall fireplaces have a lot of trouble warming more than the masonry and their immediate surroundings. Usually it relies on some sort of convection chamber in the masonry itself, that’s all well and good but they rarely feed right. Some have a blower on them, but a blower is usually 220v and power hungry.
The already warm exhaust from a miner could be piped through the fireplace apparatus continuously, and could sink into the masonry. May actually negate the need for a wood fire on some days. When the fireplace was running, it’s not like blowing air that was already warm through it would be a bad thing.

So maybe talk a bit about things like that. You and I have talked about various uses for the heat because that’s the first unintended resource from mining, but I haven’t heard anybody expound on the fact that you’re continuously moving a lot of air. I’m sure there’s things to use moving air for regardless of its temp. 

 Yeah, moving air is going to be the key in the Bitcoin mining air conditioner I'm thinking about.  

 Just looked it up.   Cool.   Now that I see the design I’m wondering where I’ve seen one before..  

I’m stuck with the squared for now 

 I wonder if you could modify the firebox to be more similar to a Rumford in some way. Especially if you used something reflective to help radiate the heat outward. Stainless steel or something. Just go grab a fridge off the side of the road and start playing around with the shape of the firebox.