Is EDR everything?

Therm_lag

EDR can be calculated and matched to boiler rating,

however, EDR is the transfer of heat from radiator to room.  The boiler

must also bring the weight of distribution system to temperature before

substantial heat transfer from distribution occurs (before EDR is fully a

factor).  How is the thermal capacity of the distribution system

figured in to balancing, steam cycle length, deadband setting?  I roughly calculate 1.5 hr full output to fully heat distribution system from room temp to 212+F.

I'm assembling a calculator to estimate thermal capacity of steam distribution system and please tell me if something of this sort exists (or tool for other purposes could be adapted).

Sorry for so many questions at once . . . hope they're good ones!  I am an energy audit practitioner and have no issue with receiving corrections and information from installation practitioners.

Response will be of value, and will be acknowledged, in  “Steam Heating: Past, Present, & Future”      presentation at the ACI 10 conference, April 2010

JStar

Well.

You're right about not just needing to heat up the radiators. You also need to heat the pipes in the system feeding the radiators. You can go by a rule of thumb by adding 33% to your total EDR (for residential systems), or you can probably find the BTUH output of the pipe and add that all up, though that seems very tedious.



You figured the boiler to need 1.5 hours to heat up all the system piping? How did you come up with that? In a typical residential home, with properly sized and working vents, you should feel the piping and radiators getting hot within minutes.

gerry gill

EDR is just

a phrase that compares something to a direct radiator..i seem to recall hearing the original sample radiator being a four column 38'' high radiator..anyways, you measure the pounds of condensate your product produces with 1 pound of steam in the radiator and i think it was 70 degree entering air and then multiply the pounds of condensate by 4 and that's now Equivalent TO direct radiation..not sure if that helped you..maybe the attachments will.

Luv'nsteam

EDR

EDR is an acronym for Equivalent Direct Radiation.  EDR was given to the world by Thomas Tredgold (early 1800's) and he figured out the heat output of one square foot (one side) of James Watt's  radiator (the very first we know of and date of 1784) with a room temperature of 70* and steam temp inside at 215* (about one pound of pressure) provided 240 BTU's of heat (per square foot).  Thus we have "square foot EDR".  See page 10 of TLAOSH, gold cover for info about EDR & BTU's.



Now here is where my mind doubts me, so correct me if I am wrong.  To figure EDR for a radiator, someone filled a vat with a carefully measured amount of paint.  One section of a radiator was dipped into the paint completely and removed.  The difference in paint amount was then figured out and converted to square feet of coverage.  Now we have square foot EDR per section.  If this is correct, I assume "they" did this for each section-size of radiator.



Multiply this number times number of sections times 240 (for steam only, 185 for hot water) and you have the heat output, in BTU's of radiation for the radiator in question.  For instance, a three column radiator measuring 9" wide per section and 45" tall has an EDR of 6.0, according to my chart from Crown Boilers.  Lets say your radiator has ten sections, you would multiply 6.0 (EDR per section) X 10 (number of sections) X 240 (BTU's per equivalent direct radiation per square foot, steam) providing an output of 14,400 BTU's for that radiator.   



For the system, in most cases, after you figure your total EDR you multiply that by 1.33 (33%, called the "pick-up" factor) and that accounts for the mains, run-outs, risers, fittings, etc.  In some cases a pick-up factor of 1.5 is used, but I currently do not recall what that/those cases may be (just reread one for instance: uninsulated pipe).



If any of this wrong, please correct me soon, so my info does not lead to someone making an error with an actual boiler replacement.  Thanks.



Thank you,

Mike





Mike

Charlie from wmass

edr is not surface area

it is a measure of heat out put that is affected by variables such as surface to volume ratios.

Luv'nsteam

What EDR is

Charlie,

Please have a look at the top-left side of page ten of TLAOSH, gold cover edition.  Perhaps I phrased it wrong?



Thank you,

Mike

Charlie from wmass

I am sorry to say I have yet to purchase

Dans book. The greening of steam is actually higher on my book list of books I will be getting.

Luv'nsteam

The Lost Art Of Steam Heat

Page 10.  My copy is highlighted, but it shouldn't matter.  Tredgolds name was on the prior page, but you get the idea.  Also, while Greening Steam is worthy of purchase, TLAOSH has far more technical data and heating history.  My two cents (and I have both!).



Thank you,



Mike

Jean-David Beyer

someone filled a vat

"To

figure EDR for a radiator, someone filled a vat with a carefully

measured amount of paint.  One section of a radiator was dipped into

the paint completely and removed.  The difference in paint amount was

then figured out and converted to square feet of coverage. "



I knew a guy (long ago; I no longer remember who he is) who worked for Harrison Radiator Corp, I believe in Lockport, N.Y. He developed a plating process that put down the same amount of metal independently of the shape of the surface. They were not going to plate the radiators sold in cars and trucks. But they did want to measure the surface area. So they weighed a radiator very accurately, plated it, and weighed it again. So if they ran the plating bath for a known time, they knew how much metal they would put down per square inch. So they could calculate the surface area. I suppose for a house radiator, using paint would not be too far off, since it is a much simpler surface than a car radiator, though it might not be as uniform as the plating process, and they would still have to know how thick the paint was.



I am always impressed with how really smart these 19th century engineers really were.

Luv'nsteam

Heat loss calcs and EDR

Gerry, after reading the two pdf files you kindly provided, I must say that replacing a boiler using methods Dan shares in TLAOSH is hugely easier than the calculations in the articles.  Good golly man, you need a physics degree to understand all that.  :  )  Also, it appears much of the text & calculations (I confess, I did not read all of the second article) is for new installations.  That said, however, I am adding four rads to my current system.  I crunched the heat loss numbers using a heat loss calculator I found online.  Armed with this number of BTU's, I divided by 240 (not 250) to determine needed EDR and then have been hunting for radiators that are close to that EDR output (so far, all are too large, but the rads I found are gorgeous and because I cannot bear to scrap even one section of ornamental iron radiator, I am still looking.  If anyone needs a fancy rad, let me know).

Thank you,

Mike