Old steam systems
Single pipe systems are the first systems used in the US and are common in older residential and some commercial buildings. Single pipe systems do not have steam traps on the radiators. These radiators rely on vents to discharge the air that gets into the system. They share a common pipe for supply steam and condensate return. It is critical that the piping be pitched properly on a single pipe system. Air is a good insulator and if you leave it in a radiator chances are you will feel the cold. These systems are subjected to a lot of water hammer as well. The water hammer is mostly caused from piping that has been changed improperly to accommodate space renovation.
Later, the two pipe system was introduced to improved the efficiency of steam systems by separating the steam and condensate line piping. A steam trap is placed at each radiator, heating coil, drip leg etc. to keep live steam in the source and remove condensate an non condensable gases to the condensate line.
The two pipe system is found in: residential, commercial and industrial applications. We run into a lot of older steam systems that were designed for high pressure that are reduced to a low pressure system for monetary reasons. With the decrease in manpower to perform routine maintenance on steam systems we find a lot of leaking steam traps present themselves during a survey. Systems designed for high pressure have steam traps designed for high pressure and some of these traps do not perform well in low pressure system conversions. Daily boiler shut downs, no bypass piping for cold start ups all contribute to these failures when a trap is designed for constant high pressure. As an example a bucket trap will allow steam to blow by the trap unless it has a reservoir of condensate. This is not the bucket traps fault. Bucket traps perform well in high pressure applications but in low pressure applications the trap can be subjected to fluctuations that sometimes cause the trap to loose prime and unless you have the manpower to go around and re-prime these traps they leak steam.
Hiring an experienced steam trap survey contractor to identify energy losses in your steam system will greatly improve your heating comfort, steam process and energy consumption.