avoiding frozen coils - Tony

tony

i have a steam coil. i have a f&t trap. i have 2# steam pressure. I have 6 ft of vertical lift to a dry cond return to receiver which (for the sake of argument) sits at atmospheric press. i.e. no backpressure from anywhere else. i have a vacuum breaker. so here is the scenario... I shut off my steam. it is -20 deg. F and outside air dampers are frozen open pulling 100 % across my coil. what are my options to remove the condensate from this coil to prevent freezing. I shold also mention out of the bottom of the coil I have a drop of only one foot to the floor (which i cannot penetrate) and my condensate pump is about ten feet away on the floor. thanks tony

DanHolohan

how about

using a spill trap just above the F&T? It could be a simple 3/4" thermostatic trap, piped off the bull of a vertically positioned tee. When the condensate backs up (as the control valve shuts) the trap will open and spill the condensate that forms between the coil and the F&T. When the coil is operating, the trap will be shut. An F&T would be better as a spill trap since it doesn't sense temperature, but you might not have the room for that.