Hydronic Seperator

Measuring Radiators to Size a Steam Boiler

Sizing Radiation for Residential Steam Boilers
Column Type Radiator	Cast Iron Cabinet Convector	Radiant Radiator (Sunrad)
Tube Type Radiator	Cabinet Convector Copper Element	Directions Calculating EDR
Wall Radiator	Cast Iron Baseboard

Measuring Radiation to Determine Sq. Ft of Steam Required

Calculating the Sq. Ft. or EDR of cast iron radiation is really simple. We can calculate it for you but hate taking your money for something so simple. If you can read a ruler and have a calculator you can do this. Steam boilers are sized on connected radiation only. This means no piping. The manufacturers have deducted 33% for piping already.

Measure the height of the radiator. This is measured from the floor not the bottom of the radiator.
Count the number of columns or tubes of the radiator
Count the number of sections that make up the length of the radiator
Using the below charts enter the left column to the height of the radiator. If between two heights go the taller number
Get the multiplier for each section going to the right to the column that has the correct number of columns or tubes per section
Multiply the number of sections by the proper multiplier for each radiator
Add up all the radiators and look at steam boiler literature of your choice. Choose the boiler closest to the calculation results

Column Style Radiator

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Disclaimer: The information found on this website is for informational purposes only. All preventive maintenance, service, installations should be reviewed on a per job situation. Any work performed on your heating system should be performed by qualified and experienced personnel only. Comfort-Calc or its personnel accepts no responsibility for improper information, application, damage to property or bodily injury from applied information found on this website as it should be reviewed by a professional.to property or bodily injury from applied information found on this website as it should be reviewed by a professional.

Tube Style Radiator

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Wall Radiator

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Cabinet Convector - Cast Iron Element

To calculate the Sq. Ft. of radiation for cabinet convectors you must first determine if the heating element inside the cabinet is copper or cast iron. Use the proper chart. This is simple, Measure the cabinet depth, height and width. Use the charts to acquire the Sq. Ft of Steam. Example: if the cabinet is 26" high, 6-1/2" deep and 43-1/2" long the sq. ft. of steam would be 39.8. Add together all convectors and other radiation and choose your boiler.

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Cabinet Convector Copper Element

To calculate the Sq. Ft. of radiation for cabinet convectors you must first determine if the heating element inside the cabinet is copper or cast iron. Use the proper chart. This is simple, Measure the cabinet depth, height and width. Use the charts to acquire the Sq. Ft of Steam. Example: if the cabinet is 26" high, 6-1/4" deep and 36-1/2" long the sq. ft. of steam would be 36. Add together all convectors and other radiation and choose your boiler.

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9A Cast Iron Baseboard

3.4 sq ft per lineal ft.

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Radiant Radiator Also Known as Sunrad

Width	Height	SQ FT per Section
5"	20"	2.25
7.5"	20"	3.40

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