Steam vents

Mike M

I came upon a steam system that spurts water out an air vent with a 30" riser when the condensate pipe (before the F&T) temp falls to about 180-185F. This was a vapor system 16 years ago I'm told. A standard boiler was installed. None of the piping is insulated. The header is about 10" above the top jacket of the unit, the pressuretrol is set to 5PSI with a 2PSI differential, it cuts in and out at 8 and 6 according to the pressure gauge on the boiler. The main riser goes straight up, where it connects to the header it uses the branch of the tee. I thought I read in one of Dans books a common mistake is to be tempted to connect a vent on a two pipe system, and should be avoided. I'm not sure,...The vent is a #75 with a 4PSI fallout pressure. I think its vented in the wrong place. These are fan coil units . The steam goes in the coil, condenses and travels down a 48" leg to a tee with a 30" riser and #75 air vent, it then goes into a Sarco F&T then to a return line. When the line temp of the said condensate line reaches about 185F the airvent falls out and the water spurting starts.... Whats up? I know lots of things were done poorly on this... It seems the one vent on the very end is the only one that does this.