An U.S. Boiler listing, from the manufacturer's published data.

Units: SI · US customary

Published specification

Nominal output	0.122 kW per foot of active length (0.401 kW/m) — the maker's net rating, 480 Btu/h per foot, ÷ 1.15: its ratings include the I=B=R baseboard code's 15 % heating-effect allowance, a comfort credit rather than heat the water gives the air
Rated at an excess of	63.9 K of water over 18.3 °C (65 °F) entering air — 82.2 °C (180 °F) average water
In a room	a 20.0–21.1 °C (68–70 °F) room reads 3.2–5.4 % under the tested rating at 82.2 °C (180 °F) average water: the model takes Δt over the air entering the part, which in a building is the room's, and the rating was taken over 18.3 °C (65 °F) entering air
Exponent n	1.238 — the output follows (Δt/Δtn)^n

Manufacturer's product page

Open this part in the app — as a component of its own, carrying the catalog's figures; or open the builder and pick it from the catalog picker. The solver runs it with the catalog's own data, at your design point or across a year of weather.

How the model reads against this maker's data

A hydronic baseboard rated per foot, against its maker's own table: the emitter's power law read from one printed column, the figure ÷ 1.15 and over 65 °F entering air, carried to every other water temperature by an exponent fitted on the printed columns

18 water cells and the steam rating; 1 listing

listed at the 180 °F, 1 gpm column — 480 Btu/h a foot ÷ 1.15, 0.122 kW over 0.3048 m at 63.9 K — with n 1.238, the least-squares fit of all nine 1 gpm columns as printed against 65 °F (largest deviation of the fit 1.7 %), the model reads every 1 gpm cell within 3.2 % (+3.17 % at 150 °F: the listing holds the 180 °F cell as printed, 480, where the fit's line reads 473), on a run of one foot and of ten. The fit is the printed table's, not a measurement's: the sheet does not say which columns were tested, and from 170 °F up its 1 gpm row is a straight line, 5 Btu/h a foot per °F, which no power law draws. That fit stands over the model's default exponent (the owner's call of 10 Oct 2026, recorded with the data): at 1.3 the model would read the 1 gpm cells −0.8 to +5.1 %; which columns were tested is a question for U.S. Boiler. The model has no flow term, so it reads every 4 gpm cell 2.5 to 5.9 % under — the uplift the sheet prints and the model leaves out. In a room: the rating is over 65 °F entering air and the model reads Δt over the air entering the part, the room's in a building, so a 68–70 °F room reads 3.2–5.4 % under the tested rating at 180 °F average water and 4.9–8.2 % at 140 °F, which the listing's page states. Not modelled: the steam rating (860 Btu/h at 215 °F), which the sheet's own 3.40 sq ft of EDR does not give (816)

From the validation page; every row is held by a test.

Listed from published data; a listing's figures are the manufacturer's, the model that runs them is ours. Solver results never depend on who has claimed what.