Data from the 2-3 am hour of Nov 16:

Boiler power 17061 Btu/h (5000 W)

Outside air temp 22.72-23.31 F

Inside air temp 70.3-73.78

Greenhouse air temp 55.53-57.69

Inside to outside temp difference 49.025 F, 27.236 C.

Building UA = 17061 Btu/h / 49.025 F = 348 Btu/hF

Building UA = 5000 W / 27.236 C = 183 W/C

Lower is better. It would probably look better if I hadn't been heating the greenhouse, but in order to get steady state with just the cabin zones heated, it will have to get colder outside.

I'm actually more interested in the circulation pump right now as I'm trying to figure out the solar hydronic system. The data I have is:

Boiler outlet 97.85 F

Cabin return A 90.27

Cabin return B 91.41

Greenhouse A 94.05

Greenhouse B 90.09

I really wish now I had a sensor on the boiler inlet to measure the mixed return water temp. As it is I don't have much choice but to assume all the loops are carrying an equal share of the flow, and use the average of the four return temps.

Distribution loop temp difference: DT = 97.85 - 91.44 = 6.395 F

Qdistrib = m cp DT = Pboiler, in steady state.

m = Pboiler/(cp DT) = 17061 Btu/h / (1 Btu/lbF * 6.395 F) = 2668 lb/hr * 1 gal/8 lb * 1 hr/60 min = 5.6 gal/min.

I looked up pressure-flow curve for the Taco 007 circulator, which is (irritatingly) labeled curve number five (dark green).

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