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Member Posts: 100
I am trying to figure the btu output of existing radiators in an old building. I have length, width and height of each. Anyone know a good site to figure the output? I'm trying to size a boiler. I know baseboard is 580/ft.

• Member Posts: 2,808
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If it's a hot water boiler, you'll want to do a heat loss load calculation to determine the boiler size. Knowing each radiator's EDR is very helpful in determining your supply water temperature at design conditions. About halfway through this booklet is the tables you can use to determine EDR.

If it's a steam boiler, you'll want to size the boiler based on the connected EDR.
Steve Minnich
• Member Posts: 100
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Thanks Steve, the heat loss calculator is nice. But I'm trying to figure the btus of the existing radiators based on their size. I'm having no luck. I know that a 6ft baseboard has 580/btu/ft =3480 btus. How many btus in a tube radiator 48 x 20 x 7 ?
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Take a pic of the radiator and post it here. Once we see it we'll know what to tell you.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting
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Thanks for the reply. I have a whole house full of radiators I need to determine the btu output of each one. Do you know a site or formula I can use.
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This is the site and if you look at pages 66 and 67 in the booklet I attached above, it shows you what the EDR is for column and tube radiators. For hot water, multiply the EDR per section by the number of sections. Multiply that number by 180. Boom.

For steam, multiply by 240. Steam guys can confirm the last number.
Steve Minnich
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Go to www.us boiler.net then click on contractor tool box then click on The Heating Helper page 65 sizing obsolete radiators
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A lot will depend on whether this is a "tube" radiator in the style of the National Aero or American Corto, or what some of us call a "pipe" radiator like a Nason or Bundy. That's why I'd like to see pictures.
All Steamed Up, Inc.
Towson, MD, USA
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Consulting