C403.3.4 Boiler Turndown
Boiler systems with design input of greater than 1,000,000 Btu/h (293 kW) shall comply with the turndown ratio specified in Table C403.3.4.
The system turndown requirement shall be met through the use of multiple single-input boilers, one or more modulating boilers or a combination of single-input and modulating boilers.
|BOILER SYSTEM DESIGN INPUT (Btu/h)||MINIMUM|
|≥ 1,000,000 and less than or equal to 5,000,000||3 to 1|
|> 5,000,000 and less than or equal to 10,000,000||4 to 1|
|> 10,000,000||5 to 1|
For SI: 1 British thermal unit per hour = 0.2931 W.