36,000 BTU is three tons, a mid-size central air system and a common multi-zone mini-split outdoor unit. By the room rule it cools up to about 1,800 sq ft of open space, with a best fit of 1,500 to 1,800 sq ft. Real houses spread widely around that: a tight new house in a mild climate can need less, and an older, leaky one in Phoenix can need more.
A shaded, well insulated space stretches to about 2,220 sq ft; a sunny, poorly insulated one stops around 1,420. At this size, get a Manual J. Oversizing a central system by a ton is expensive twice: the equipment costs more, and it short-cycles, leaving the house cool but humid. The old contractor habit of 400 to 600 sq ft per ton often lands higher than a real load calculation.
As heat, 36,000 BTU covers about 900 sq ft in a moderate climate, 1,200 in a hot one and 650 in a cold one. That gap is why a heat pump sized for cooling is often too small for heating up north, and why cold-climate installs pair it with a cold-climate model or backup heat.
At an EER of 11 a 36,000 BTU system draws about 3,270 W, 14.2 A at 230 V while running; the breaker size comes from the nameplate, not this number. Converted, 36,000 BTU/hr is 10.55 kW, 10,551 W or 3 tons.
How many square feet a 36,000 BTU air conditioner cools
Largest room the unit keeps up with, rounded down to the nearest 10 sq ft. Two occupants, 8 ft ceiling and moderate climate unless the row says otherwise.
| Room | Cools up to |
|---|---|
| Shaded, good insulation | 2,220 sq ft |
| Average room (baseline) | 1,800 sq ft |
| Very sunny, poor insulation | 1,420 sq ft |
| Hot climate, very sunny | 1,480 sq ft |
| 10 ft ceiling | 1,440 sq ft |
| 4 people instead of 2 | 1,740 sq ft |
| Kitchen in the space | 1,600 sq ft |
How many square feet 36,000 BTU of heat covers
By climate and insulation. For a gas heater, use its output rating (input × efficiency).
| Climate | Poor insulation | Average insulation | Good insulation |
|---|---|---|---|
| hot | 1,000 sq ft | 1,200 sq ft | 1,410 sq ft |
| moderate | 750 sq ft | 900 sq ft | 1,050 sq ft |
| cold | 540 sq ft | 650 sq ft | 770 sq ft |
36,000 BTU in kW, watts and tons
| Kilowatts | 10.55 kW |
| Watts | 10,551 W |
| Tons of cooling | 3.00 tons |
| Power an AC this size draws (EER 11) | about 3,273 W, 14.2 A at 230 V |
| Power an electric heater needs for this output | 10,551 W, 44.0 A at 240 V |
kW and watts here are heat output, the number on the box. An air conditioner moves that much heat while drawing far less electricity; an electric heater draws exactly as much as it puts out.
36,000 BTU questions
How many square feet does a 3 ton AC cool?
About 1,800 sq ft of open space by the 20 BTU per sq ft rule, with a best fit of 1,500 to 1,800. For a central system, a Manual J load calculation is the right way to confirm it.
What is 36,000 BTU in kW?
10.55 kW of cooling, or 3 tons. The system draws about 3,300 W of electricity at an EER of 11, less if it is a high-efficiency model.
How many amps does a 36,000 BTU AC use?
About 14 A at 230 V while running, for a unit with an EER of 11. The circuit is sized from the maximum breaker size printed on the outdoor unit's nameplate.