Dual Tube Steam Coil

[griz]

I am dealing with an old old carrier air handler m#39BAO60B10. It has a dual tube steam coil. I have steam present at supply feeding coil and leaving condensate hot. My problem is no heat transfer. Less than 10 degree temp split. Outside air dampers closed. Does anyone no how these coils operate. I have heard that steam flows in outer tube and somehow condensate travels down the inner tube.

[onetime]

I am dealing with an old old carrier air handler m#39BAO60B10. It has a dual tube steam coil. I have steam present at supply feeding coil and leaving condensate hot. My problem is no heat transfer. Less than 10 degree temp split. Outside air dampers closed. Does anyone no how these coils operate. I have heard that steam flows in outer tube and somehow condensate travels down the inner tube.

They are called frost proof coils but they will still freeze. I believe the steam enters in the inner tube and exits the outer tube as condensate.

[onetime]

They are called frost proof coils but they will still freeze. I believe the steam enters in the inner tube and exits the outer tube as condensate.

I found it in my books. The coil has a special tube within a tube distrubution system with special orfices on the tube that distribute steam equally and evenly throughout the length of the tube. This assures max transfer and uniform leaving temp over the whole coil and resists freze up by eliminating cold spots. And it does appear that the steam enters the inner tube, exits the orfices the full length of the tube and exits the outer tube.:)

[jogas]

First, they can and do freeze.
Second, check the coil temp along the run of all the tubes and see if your getting heat output all the way across. This test works best with the fan on.
I have been told that the supply tube can fail (crack, deteriorate, or leak) and allow steam to bypass the coil. The steam will travel from the inlet header to the outlet header and only see part of the intended heat transfer surface, reducing temp rise/capacity.
jogas

[onetime]

First, they can and do freeze.
Second, check the coil temp along the run of all the tubes and see if your getting heat output all the way across. This test works best with the fan on.
I have been told that the supply tube can fail (crack, deteriorate, or leak) and allow steam to bypass the coil. The steam will travel from the inlet header to the outlet header and only see part of the intended heat transfer surface, reducing temp rise/capacity.
jogas



I thought I said that, Idid, I did, they will still freeze!!:D :D

[jogas]

I thought I said that, Idid, I did, they will still freeze!!:D :D

Sorry, I didn't read your reply, just the original post.
jogas