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Old Radiator EDR to BTU

Brad White_9
Brad White_9 Member Posts: 2,440
Each radiator style has an associated Square Feet EDR for each section, height and number of tubes. Buy Dan's book "EDR" as one place to start. They do vary, those radiators.

Typically, the 240 BTUH per EDR rule is for 215 degree steam (1 PSIG) in a 70 degree room.

With hot water at an average temperature of 170 degrees (e.g. 180 in/160 out) the BTUH drops to 150 in the same 70 degree room.

Typical gain or degradation depending on the average water temperature is about 20 BTUH per ten degrees change.

In Other Words:

AWT degrees F/ BTUH per EDR

100/ 10

110/ 30

120/ 50

130/ 70

140/ 90

150/ 110

160/ 130

170/ 150

180/ 170

190/ 190

200/ 210

Comments

  • Tim_43
    Tim_43 Member Posts: 2
    Old Radiator EDR to BTU

    Trying to determine how many btu's where emitted from an old cast iron radiator that has been converted to hot water. My understanding is - there were 3 types of cast iron radiators, column, slim-tube and large-tube. Column and large-tube were manufactured prior to 1950 and slim-tube was and still might be manufactured today. I'm assuming that I am dealing with column or large-tube. Was each radiator made up of several "columns" or "large-tubes" separated by spacers? If so, would the surface area be calculated for each "column" or "large-tube" rather than the square footage of the front surface of the radiator (i.e. 4 ft. height X 10 ft. length = 40 square feet). I am thinking that the example is wrong and that the surface area is calculated for each "column" or Large-tube" of the radiator. That being the case, how many square feet are in (1) "column" or "large-tube" that is 45 inches high X 15" deep? I'm coming up with 10. There are 21 "columns" or "large-tubes" so that would total 210 sq. ft. - if one sq. ft. is equal to (1) EDR and (1) EDR is equal to 240 btu's is it fair to say that 210(sq.ft.) X 240 (btu's) = 50,400 btuh or 50.4 MBH
  • You're on the right track

    Square feet EDR is a measure of the surface area of radiating metal. Heat output might vary between radiators of the same dimensions when they're different types. The idea is to consider the surface area - the interface between the hot steam or water inside the radiator and the cooler air in the room - to level the playing field.

    Here's an online guide that describes cast iron radiator sizing, with charts for standard radiator types:

    http://www.colonialsupply.com/resources/radiator.htm

    Dan's Lost Art book has even more charts for standard radiators, and the EDR book has sizing information for more esoteric radiation.

    Mark
  • Tim_43
    Tim_43 Member Posts: 2
    Thanks for the info!!!!

    Thanks for the information guys! Really appreciate it. Heading back out to confirm exactly what they were. Things are starting to make sense.
    Sanddy0908
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    To know one's EDR

    is to know one's self, Grasshoppa.
  • Enlightenment

    Best of luck with your project, Tim!
This discussion has been closed.