The heat source shall be sized to the design load.
Water heaters utilized for combined space-heating and water-heating applications shall be listed or labeled in accordance with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer 's installation instructions. The total heating capacity of a dual purpose water heater shall be based on the sum of the potable hot water requirements and the space heating design requirements corrected for hot water first hour draw recovery.
For SI units: 1000 British thermal units per hour = 0.293kW
|Gas, 75000 Btu/h or less||CSA Z21.10.1|
|Gas, Above 75000 Btu/h||CSA Z21.10.3|
|Electric, Space Heating||UL 834|
|Solid Fuel||UL 2523|
The output performance on tankless water heaters shall be determined by the temperature rise and flow rate of water through the unit. The ratings shall be expressed by the water temperature rise at a given flow rate. Manufacturers flow rates shall not be exceeded.