The two main ones that have big storage built in, that I know about, are Garn, and Switzer. Garn is open, Switzer I think is pressurized. I don't think either are outdoor units though. Although I imagine you could put them in an outbuilding.
Your post reminded me of another brand of gasser. Portage and Main, I think, looked like a nice unit that I saw a few years back. Of course H.S. Tarn has made them for a long time. Very Good quality from what I’ve heard. Econoburn has an outdoor gasser. Garn have a good reputation. Most outdoor wood boiler manufacturers are now making outdoor gassers. Just so much more efficient. They probably saw campinspecter on his roof sniffing clean air coming out of his stack and realized they were behind the times. LOL
I have an outdoor gasser. Works awesome. Heatmaster brand. Hold 200 gallons of water, very low on wood consumption so far.
Keep in mind that a proper heat loss calculation can really help you size the boiler right. An E100 would probably not be large enough depending on the size of the two houses. Sizing the boiler correctly is very important.
Helps to determine how much BTUs are needed (boiler size) I’m not certain this is the best one, but it is an example. 5-Step Heat Loss Calculation
How do you heat your dhw with your wood stove.? Plate heat exchanger or shell in tube. I had a plate but it got solidly plugged with calcium. Wasn’t sure how to clean it & still have it be safe enough for potable water. It only plugged on the dhw side not the stove side. I don’t feel like the shell & tube unit does as good a job as the plate exchanger.
A shell and tube would have to be very long to achieve the same area of heat exchanger surface. Part of the efficiency of a flat plate Hx is the flow is split into many slower paths with more molecules of water in contact with more hx metal. The only way to approximate the same efficiency of exchange would be with many shell and tube Hx in parallel flow, which would cause the flow rate to drop and give more time for heat transfer
I tried CLR for my coffee maker, i think i should have diluted it a bit, even after rinsing the next couple of pots tasted kinda funny Wasn't too concerned, supposed to be good for the environment, or vinegar soak would wor too
I use a 5x12, 30-plate Taco exchanger. It's probably a hair too small, should have a 40-plate I think. Never had a problem with calcification but then all my DHW goes through a softener first from the well.
If CLR doesnt do it I'd try coffee maker descaler. There's likely a common chemical that would clean it right up but I'm not up on my chemicals.
Coffee maker cleaner is sodium carbonate, not baking soda but close. If you have a pool or hot tub, ph increaser is sodium carbonate. Works great and cheap.