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

This is an AMP page - Open full page! for all features.

Heat Emission from Radiators and Heating Panels

Sponsored Links

Heat emission from a radiator or a heating panel depends primarily on the temperature difference between the hot surface and the surrounding air. The heat emission can be calculated

P = P50 [((ti - tr) / ln((ti - ta) / (tr - ta))) (1 / 49.32)]n                                     (1)

where

P = heat emission from radiator (W, J/s)

P50 = heat emission from radiator with temperature difference 50 oC (W)

ti = water temperature inlet (oC)

tr = water temperature outlet (oC)

ta = surrounding air temperature (oC)

n = constant describing the type of radiator (1.33 for standard panel radiators, 1.3 - 1.6 for convectors)

Note that radiators are in general designed for middle panel temperature 70oC - and surrounding air temperature 20oC (difference 50oC)

Example - Heat Emission from Radiator

The heat emission from a radiator with nominal*) heat emission 1000 W with water inlet temperature ti = 70oC and outlet temperature tr = 50oC can be calculated

P = (1000 W) [(((70 oC) - (50 oC)) / ln(((70 oC) - (20 oC)) / ((50 oC) - (20 oC)))) (1 / 49.32)]1.33

    = 736 W

*) nominal when inlet water temperature ti = 80oC, outlet water temperature out tr = 60oC and surrounding air temperature ta = 20oC

Radiator Heat Emission Calculator

Heat Emission and Water Flow

The calculator below can be used to calculate heat emission and water flow from a radiator operating outside the standard conditions - like increasing or decreasing the water inlet or outlet temperature or increasing or decreasing the surrounding room air temperature.


Return Temperature Water and Flow

The calculator below can be used to calculate the water return temperature and the water volume flow through radiators based on actual heat emission and inlet water temperatures.

Oversized radiators are quite common since it is almost never possible to adapt a standard radiator exactly to the required heat loss from a room. With the calculator below it is possible to study the consequence of out of standard heat emission when a radiator is oversized.

- heat loss from the room covered by the radiator (W)


When checking heat emission capacities of radiators - be aware that testing standards differs. Examples of standards:

  • BS 3528 "Specification for convection type space heaters operating with steam or hot water" (withdrawn, replaced by BS EN442) - flow temperature 90oC, return temperature 70oC, air temperature 20oC
  • BS EN442 "Specification for radiators and convectors." - flow temperature 75oC, return temperature 65oC, air temperature 20oC

Testing the same radiator with BS EN442 compared to BS 3528 reduces the heat output with approximately 11%.

Sponsored Links

Related Topics

Heating Systems

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

Related Documents

Arithmetic and Logarithmic Mean Temperature Difference

Arithmetic Mean Temperature Difference in Heat Exchangers - AMTD - and Logarithmic Mean Temperature Difference - LMTD - formulas with examples - Online Mean Temperature Calculator.

Heat Loss from Buildings

Overall heat transfer loss from buildings - transmission, ventilation and infiltration.

Heating Systems - Steam and Condensate Loads

Calculating steam and condensate loads in steam heated systems.

Hot Water Heating System - Design Procedure

Hot water heating system design procedure with heat loss, boiler rating, heater units and more.

Hot Water Heating Systems - Online Design Application

Free online design tool for designing hot water heating systems - metric units.

Hot Water Heating Systems - Online Design Application, Imperial Units

Online design tool for hot water heating systems.

Radiators - Heat Emission

Calculate heat emission from column and panel radiators.

Steam Radiators and Convectors - Heating Capacities

Steam radiators and steam convectors - heating capacities and temperature coefficients.

Sponsored Links

Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

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 the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.