Yes, as Antonio (espana2005) said, some DCU’s do not have a coke condensate drum.
In the coker I worked some years ago, the coke drum overhead lines had ball valves, and after the point the lines from two drums would join, we had a butterfly valve. This butterfly valve was normally open 100 %, and when we were going to warm up a drum, we would partially close this butterfly valve to force the hot vapors from the online coke drum into the “cold” coke drum. Some older cokers do not have this set up, while some newer ones use a “ring valve” instead of a butterfly valve.
There is some information on ring valves here: http://www.velan.com/products/pdfs/vel-cbv-2002-web.pdf
Hope this helps,