Originally a trade name, the word is used for any steam pressure control with a main setting and a differential. On residential and small commercial low-pressure steam, the cut-out is usually set around 1.5 to 2 psi, because one-pipe and two-pipe systems need only ounces to heat. It mounts on a pigtail siphon so live steam never reaches the bellows.
Pressuretrol's set at 8 psi on a one-pipe system, that's why the vents are spitting, knock it back to 1.5.
Steam veterans say a house steam system that needs more than 2 psi has a venting or piping problem, not a pressure problem.
Also heard as
- pressure control
- steam pressure control
Related terms
Operating control
The automatic-reset control that cycles or modulates the burner to keep steam pressure or water temperature in range.
Pigtail
A looped siphon pipe between a steam boiler and its pressure gauge or control, filled with condensate to block live steam.
Differential
The gap between the point where a control turns the burner on and the point where it turns it off.
High limit
A safety control that shuts down the burner if pressure or temperature rises above the normal operating range.