Your home
Estimated design heating load
—BTU/hr
That's roughly — of heating capacity, or about — BTU/hr per square foot on a design (near-coldest) day.
Can a radiant floor carry it?
—
What this means. The design heating load is the peak output a heating system must
deliver on the coldest expected day. Sizing to it matters in both directions: an oversized
system short-cycles, wastes fuel, and wears out sooner, while an undersized one can't keep
up in a cold snap. A heated floor has a practical output ceiling — comfortable floor surface
temperatures cap most residential radiant floors at roughly 25–35 BTU/hr per square foot of
floor. When a room's load per square foot runs higher (large glass areas, high ceilings, weak
insulation), it's normal to add supplemental output — panel radiators, a kickspace heater, or
envelope improvements — rather than push floor temperatures uncomfortably high.
How this estimate is made (educational, not precise): load = area × climate factor
(mild 25 / moderate 35 / cold 45 / severe 55 BTU/hr·ft²) × insulation factor
(poor 1.30 / average 1.00 / good 0.82 / excellent 0.68) × (ceiling ÷ 8). This is a
rule-of-thumb approximation. An actual installer sizes from a room-by-room Manual J heat-loss
calculation using your home's real construction, orientation, windows, and local design temperature.