Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Hot Water Boiler - Circulation Rates

Boiler power and water flow - Imperial and SI-units.

The relation between

  • boiler capacity (or power)
  • temperature drop of the water flow in a system serviced by boiler
  • circulated water flow

are indicated in the diagrams below:

Water Circulation - Boiler Capacity in BHP - Temperature drop in degrees Fahrenheit

Hot-water generators - water circulation rates bhp

  • 1 gal (US)/min = 6.30888x10-5 m3/s = 0.0227 m3/h = 0.06309 dm3(liter)/s = 2.228x10-3 ft3/s = 0.1337 ft3/min = 0.8327 Imperial gal (UK)/min
  • 1 hp (English horse power) = 745.7 W = 0.746 kW = 550 ft lb/s = 2,545 Btu/h

Water Circulation - Boiler Capacity in MBtu/h - Temperature drop in degrees Fahrenheit

Hot-water generators - water circulation rates - MBtu/h

  • 1 Btu/h = 0.293 W

Water Circulation - Boiler Capacity in kW - Temperature drop in degrees Celsius

Hot-water generators - water circulation rates - kW

  • 1 kW = 3,412 Btu/h = 1.341 British hp

Example - Water flow through Boiler

A boiler with capacity 50 kW increases the temperature of the circulated water with 20oC - the water flow through the boiler according the diagram above is 

0.6 kg/s

Related Topics

  • Combustion

    Combustion processes and their efficiency. Boiler house and chimney topics. Properties of fuels like oil, gas, coal and wood and more. Safety valves and tanks.
  • Heating Systems

    Design of heating systems - capacities and design of boilers, pipelines, heat exchangers, expansion systems and more.

Related Documents


Search is the most efficient way to navigate the Engineering ToolBox.

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with older versions of the amazing SketchUp Make and the newer "up to date" SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp Make/Pro from the Extension Warehouse !

Translate this Page

Translate this page to Your Own Language .

About the Engineering ToolBox!

Privacy Policy

We don't collect information from our users. More about

We use a third-party to provide monetization technologies for our site. You can review their privacy and cookie policy here.

You can change your privacy settings by clicking the following button: .


This page can be cited as

  • The Engineering ToolBox (2008). Hot Water Boiler - Circulation Rates . [online] Available at: [Accessed Day Month Year].

Modify the access date according your visit.

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Unit Converter