Read the time basis first
An HVAC chart should normally say BTU/h, not just Btu. BTU/h is a heat-transfer rate used for capacity. Check whether adjacent columns show thermal kW, refrigeration tons, or electrical data before comparing them.
Common conversion rows
| BTU/h | Thermal kW | RT | Meaning |
|---|---|---|---|
| 6,000 | 1.76 | 0.5 | Same thermal rate in three units. |
| 12,000 | 3.52 | 1 | One refrigeration-ton convention. |
| 24,000 | 7.03 | 2 | Two refrigeration tons. |
| 36,000 | 10.55 | 3 | Three refrigeration tons. |
Use a chart in the right order
- Calculate or obtain the required heating/cooling load with the appropriate method.
- Use the chart to express that thermal rate in the units used by a specification.
- Check manufacturer performance data at the design conditions.
- Review airflow, duct distribution, humidity, and local requirements before selecting equipment.
What a BTU chart cannot show
A chart does not account for solar exposure, envelope performance, outdoor air, humidity, occupants, ceiling height, ducts, or equipment performance. Room-size rules added to generic charts are screening shortcuts, not a substitute for a documented load calculation.
Open the full conversion table
Check a larger set of BTU/h, kW thermal, and refrigeration-ton relationships.
HVAC BTU Reference TableFAQ
Can a BTU chart select equipment?
No. It converts or compares capacity; final selection requires a suitable load calculation and manufacturer performance data.
Why does a chart list kW?
kW provides a metric expression of thermal capacity. Confirm that it is labeled as capacity, not electrical input.