Replacing a steam coil

Bill Wolf

I'd like to go to a 2 row, 2 coil replacement, at 500,000 btu ea coil. Can I use the existing piping? What is the maximum velocity for steam piping? Coil is for a Gym Ahu (commercial.) The new coils were quoted at 1 1/2 in supply's, isn't that too small for this edr? (500,000 / 240= 2083 edr)

DanHolohan

drawing

DanHolohan

Bill

what pressure are they using?

DanHolohan

turning it 90 degrees

Bill Wolf

Dan, the pressure is 5 psi.

DanHolohan

Should have clarified

Sorry, Bill. Is that the pressure required at the inlet to the coil? If so, what pressure is at the boiler (or PRV station) and how far does the steam have to travel to get from there to the coil?

Also, are you trying to move 1,000,000 BTUH (500,000 for each coil, right?) through a single pipe, or will you split the load through the existing supply lines? I'm seeing one 2-1/2" line and one 3" line.

As for the 1-1/2" tapping on the coil, check out this article in Hot Tech Topics:

http://www.heatinghelp.com/newsletter.cfm?Id=71

Tony Conner

A Coil...

... is just a heat exchanger, and it's always dangerous to size the piping off the connections. Is the 500,000 BTU figure the maximum rating from the manfacturer? (I suspect it is.)

Using 15,960 CFM with a delta-t of 24.7, I figure you'll need 426 lb/ hour of steam. At 5 PSIG, this WILL fit through a 1-1/2" line, but just. (It's about 200 feet per minute, which is where I size industrial lines of maybe 100 feet long for peak loads, and noise isn't an issue.) Pressure drops are also a consideration. If 5 PSIG is the system pressure, you haven't got much to work with. At 1-1/2", the line will need to be pretty short, and you may get some velocity noise at high loads. There will also be NO room for any additional loads on this line.