Steam velocity question for Dan H

DanHolohan

you're doing it correctly. Sorry for the delayed reply. I've been in Iowa all week and nearly missed your post. Thanks.

joe lambert_2

Steam velocity question for Dan H

Dan,

ON page 46 of your book “The Lost Art of Steam Heating” you explain how to figure out the exit velocity of steam coming from a boiler with different sizes of schedule 40 pipe for the riser. On page 45 you wrote that you can figure out lbs. hr. buy taking the EDR and dividing that by 4 or taking the load in BTU hr. and dividing that by 960. My question is should I use the EDR or net I.B.R. lb. hr. rating that the manufacturer states, which includes a pickup factor of 1.33 built into the rating. In other words I have a boiler with an EDR rating of 325 sq ft, which includes the pickup factor of 1.33. If I use that rating in the formula for exit velocity I get a lower exit velocity but the boiler actually has an EDR rating of 325 * 1.33 = 432 sq. ft. The pickup factor is included in the manufacturers rating so that when you size a boiler the installer doesn’t have to add a pickup factor to the total radiation for the house. What I really should be using is the D.O.E. capacity of the boiler and dividing that number by 960 to get the actual lbs. hr rating? In this case the D.O.E. rating is 104,000 so 104,000/ 960 = 108.3. Am I doing this correctly? The Boiler I used as an example is a Weil McLain EG 40.

joe lambert_2

DOE capacity is it then

Thanks Dan for your help.