Hi Folks, quick intro and I'll jump right into the questions.
I'm Ned, I live in central NY and I have a 12' x 20' stand alone woodshop which I love spending time in, but hate shutting down during the coldest winter months. I"m looking into a mass heater for my shop, because of the sawdust and what not, I'd prefer to have an external heat source. I've been researching RMH's, watching numerous youtube videos etc... and I just discovered this forum the other day in my research.
This really caught my interest, because a) it saves square footage in my small shop, and b) the fire is external from the structure. Acquaintances of ours recently lost their house to a wood stove (no injuries,thankfully, but pretty awful). Anywho, I'm thinking that borrowing Van's plan for a barrel stove firebox with a heat exchanger, and feeding three or four barrels in the shop (first one metal, then food grade plastic 'downstream') will be just the ticket. I'd have a pump to circulate the water when I have the fire going. I'd really like an RMH, but I don't want to give up too much floor space in the shop. I do enough 'dancing' in the shop with the tools as it is. with only 240sf in the shop, every sf I can not tie up would help.
In his feed, Van talks about deliberately under-sizing the heat exchange coils, or not trying to get every ounce of heat out of the burn so that the plastic barrels he uses won't melt.
To that end, my thought is to build a two barrel vozelgang fire/exchanger similar to what Van uses, enclosed in a masonry board (durarock?) box, and some rock wool. The lower barrel would be the fire chamber, the upper barrel serving for where the copper coils piping to a 30 gallon metal barrel in a Cob enclosure in one end of the shop near the doorway. from there I would run pex tubing running from the top of that barrel to 1 or more other plastic barrels and/or pipes elsewhere in the shop. That would loop with a return feed all the way back to the 1st barrel and back to the heat exchanger. Currently a kerosun heater gets the shop 'comfy' in about half an hour, but Kero isn't cheap. I have loads of scrap wood and/or a face cord or two would help get me through the cold months.
Here's a quick sketchup 'plan'...
the 'lines' running between the barrels represent the pex tubing. In the close up the feed lines from the fire box to the 1st tank would be copper.
Alternatively, if I decide to put a 'regular' Cob RMH in, it would be approximately like this:
Note, the 'doorway' would be filled in with a door and window in either case (as that is roughly what is there now).
I'll dig around and ask some more questions as my plan progresses. THanks for looking and any advice.
Companion Planting Guide by World Permaculture Association