Thermostatic Steam Traps

Thermostatic radiator traps are designed to keep steam in a radiator so that heat can be efficiently given up to a room. This is accomplished by an element that closes off to steam. Once steam cools and turns into condensate these traps open up and allow the condensate to flow back to the boiler. At start-up thermostatic radiator traps remain open and allow air and low temperature condensate to pass.

A thermostatic element inside the trap makes this “steam trapping” possible. These thermostatic elements contain a fluid which boils at a lower temperature than water. As temperatures rise the element starts to close and finally shuts as steam reaches it. This process keeps steam out of the return lines. Eventually the steam cools and turns into condensate. The thermostatic element opens as the temperatures drop. Condensate is then released back to the boiler.

In most cases thermostatic radiator traps operate at low pressures, less than 25 psig. There are occasions where these traps are used in industrial and commercial applications. In these situations a different thermostatic element is used that typically handles pressures up to 125 psig.left