In an age when a three-year-old cell phone is considered to be obsolete, steam heating systems, which are often well over 50 years old, get no respect. However, a steam system that is functioning properly can actually be relatively efficient, despite the inherent limits on boiler efficiency. Consider that heat is distributed to all 2.8 million sq ft of the Empire State Building using only the natural expansion of water into steam and zero fan or pump energy.
Steam heating systems are common in older commercial buildings in urban areas. These systems need reasonable maintenance like the carburetors of yesteryear. However, even systems that are properly maintained can present problems.
Efficiency is Out the Window
One reason for steam's bad reputation is that it can be very difficult, or impossible, to adjust heating in individual zones, causing certain areas to be overheated. In order to regulate temperature, it is common for occupants to open windows, allowing energy to literally flow out the window. One way to keep energy in the building where it belongs is to install thermostatic radiator valves.
How They Work
A thermostatic radiator valve is a self-regulating valve fitted to system radiators to control the temperature of a room by changing the flow of steam to the radiator. They are available for both one-pipe and two-pipe steam radiators and use thermostatic elements with no electronics.
On a two-pipe system, a thermostatic radiator valve replaces the manual steam control valve. The thermostatic element opens or closes the valve to allow more or less steam into the radiator to maintain the desired room temperature. A dial allows the room temperature to be adjusted up or down as desired.
In a one-pipe system, steam enters the radiator and condensate exits through the same pipe, so the valve must be left open at all times. In this case, the thermostatic radiator valve replaces the air vent and will not release air from the radiator until heat is needed. One-pipe units are generally less precise than the two-pipe variety, but they can still be effective.
No Magic Bullet
It is important to remember thermostatic radiator valves are not a substitute for proper maintenance and controls. Regular maintenance of steam traps and air vents is required to ensure that a system is functioning properly. Proper boiler controls adjustments and improvements can also significantly impact a system's overall efficiency.
For better or worse, many steam systems will be with us for years to come, due to the high cost of upgrading to hot water or other types of HVAC systems. Despite their limitations, with proper controls and maintenance and use of thermostatic radiator valves, these systems can operate much more efficiently and comfortably than many people realize.
(This is an article from the Michaels Energy newsletter. Subscribe to that newsletter at www.michaelsenergy.com, and follow the firm on Facebook at Michaels Energy.)