Permies Design Introduction & Questions

The heater will be located in the basement, and the main bell will extend upward into the floor space above, ending at about 15 inches above finished floor height. I’ve already completed the heat‑load calculations, and a 7.5" system should let me run one full burn during the shoulder seasons and two full burns per day in mid‑winter, which fits my heating plan well.

Right now I’m considering either a Sidewinder or a DSRv2 core. I’m leaning toward the Sidewinder because of the compact footprint, but I’d appreciate input from anyone who has built both.

I’m pretty much locked in on using a double‑masonry bell, with the flue vent exiting high in the basement. I’m also kicking around the idea of a raised core to move the heater away from the concrete floor and make fire starts easier for me.
I’d really appreciate any advice, examples, or lessons learned that could help me refine this design before I start building.

Questions:
• Which core type gives the smallest footprint at 7.5"?
• Can a Sidewinder exit into the bell from any of the four directions — left, right, front, or back?
• Is there a repository of SketchUp (.skp) heater designs? I found some of Peter van den Berg's designs already.  Ideally something using imperial firebrick sizes (9×4.5×2.5") or splits.

I’m excited to get this design underway and would really appreciate any advice, examples, or models that could help me refine the layout.

Thanks in advance for your help!  Your gracious sharing and help, makes big DIY projects like this possible for the rest of us.

Hi Jim
In my opinion, the newest variant, Shorty core, has the smallest footprint.
The DSR variants may be slightly smaller, but I am told they are a more difficult build.
Keep in mind I have never built a DSR core.

Now about sidewinders.
They only exit left or right, or they would not be a sidewinder.
A first-gen Batchbox or a Shorty core can be built as a sidewinder; a DSR, I think, cannot.  (I could be wrong)
I haven't built a Sidewinder myself, but many have, with no complaints.
Here is what Lasse Holmes told me: he designed the very first Batchboxes and built the very first Sidewinder variant.
The Sidewinder was a good design. He had one in his cabin in Homer, Alaska, for over two years.
However, he said it was a fussy starter; once he determined how it liked to be started, he had no trouble with it... But his wife and daughter had nothing but trouble starting it. Eventually, he replaced it with a conventional Batchbox design and all were happier.

I have a 6" Shorty core with a single-skin bell
A 6" first -gen with a double-skin bell.
And a hybred 7" first gen with double barrels and a single-skin bell.
They all work perfectly, I could not be happier with them.