Pulling condensate

David Hohengasser

I have a single pipe steam system. My "A" dimension is 30", so it is close to the 28" minimum. I have a 1" line off a 2" main. It travels about 5 feet with counterflow back to the main. Then it drops down vertical 2 feet to an elbow at the floor. Then it starts an uphill run. There is a 6" nipple and then a tee. Off the tee is the return to the boiler. Then it starts an uphill run of 10 feet to the radiators. At the end of the 10 feet is a tee so it feeds two small radiators. Both are 12 EDR. The uphill pitch is 2" in 10 feet and there are no sags. Line is insulated completely. About halfway through the cycle, I start to have surging noises which I assume is condensate not being able to get back to the boiler and being pulled into the radiator. I have closed the vents to a pin hole size in an attempt to slow the flow of steam and let the condensate back to the boiler with no luck. System is on a vaporstat at 2 oz. and 10 oz. The surging starts at about 3 oz.

I was told a 1" main can feed 28 EDR and I have 26. Is the EDR capacity of a 1" line reduced in a counterflow sitiuation? If I turn one radiator off and run just 12 EDR, I am OK. Any suggestions?

The tee at the base of the counterflow where the return goes back to the boiler is bushed from 1" to 3/4" and it is positioned horizontally with just a slight downhill tilt. Could the little puddle of condensate that sits there be casuing the problem?