New basement fin tube design

Masshole888

I’m looking for some help with a basement fin tube heating design. I have a 1971 ranch house on Cape Cod (MA) with hydronic baseboard on the main floor. The basement was previously partially finished and had a zone valve added for it and a single Taco 007e circulator for 2 zones up and the one in the basement. The 2 finished rooms, about 130-140sf each, had about 10-12 ft of 3/4 “ baseboard in each. These were removed in the fall during the demo that was needed for the renovations. Without any heat and with no insulation, the space never drops below 66 deg including on stretches of very cold days (low in teens, highs ~30). The foundation is poured concrete, almost completely below grade and walls have recently been 2” spray foamed.

We’re finishing the basement with a 80sf bathroom/laundry, two 130-140sf bedrooms and an open common space partially divided by the stairs in the center at about 125 and 160sf.

I’m trying to lay out the design for the basement heat but having trouble getting a good read on heat loss for each room since the calculators I find on line don’t have an option for basement wall construction, or at least I’m not understanding how to use them for that.

Using Cool Calc, I’m getting 23,300BTU for the 950sf living space but this is for the first floor since I’m telling it about the framed construction, roof, unconditioned basement below, etc. What’s the best approach to use this, or any of the other calculators, to get a room by room heat loss with basement construction? Should I expect the heat loss to be higher or lower in a basement versus the main house with insulated 2x4 construction?

Second question is whether I’d be ok with a single loop or something else? I’ve been leaning toward having the ability to adjust rooms separately to some extent. This would be meant to get it dialed in as opposed to having ability to adjust day to day like with dedicated t-stats. For this approach, I’ve been thinking about running a supply and a return down the middle and pulling a separate loop for each room, a bit like a home run set up but with less pipe than if I were to pull them all from a manifold in the utility room at one end of the house. Balancing valves would need to be at the baseboards if that’s reasonable to do. Let me know if this is overkill for a system of this size in this kind of space.

I can provide more detail if needed. Any thoughts are appreciated.