About: Heating Help

This month we are going to look at steam traps. A steam trap’s function is to allow air and condensate to leave the radiators and steam piping and prevent steam from entering the condensate return piping. There are various types of steam traps in use. For our purposes we are only going to cover the two main types used in steam heating systems. The most common is the thermostatic radiator trap. Every radiator is equipped with one, with the exception of a one pipe system. Radiator traps come in two main types – angle and straight way. Both types have similar construction, a body, cap, thermostatic element, and a union tail. The thermostatic element is the heart of the trap, It expands and contracts with the steam and condensate temperature. When the element is in contact with the steam it expands closing off the exit...

The loss of vacuum in a steam system is caused by any one of the following 3 conditions: 1. Loss of steam 2. Too much steam 3. Air Leaks Below I will discuss the 3 conditions. Firstly, a loss of Steam can be caused by a boiler shut down or the main steam valve being closed or not open enough to provide sufficient steam. Secondly, if there is too much steam in the system, the steam will continually fill the radiators with steam.  As a result, no vacuum will occur in the system. And lastly, air leaks tend to occur under various circumstances – the most common being the radiator valve.  The correct type of radiator valve should be a packless valve.  Very often, the packless valve is replaced with the packed valve.  Over a period of time the packing dry’s out allowing air to enter the system....

To achieve the most efficient operation of a steam system, controlling the steam flow is essential.  This requires varying the rate of steam entering the system.  In most vacuum systems this control is achieved by the main steam valve.  This could be a weight and lever valve, a motorized steam valve or in some cases just a globe valve (a gate valve should not be used for throttling service). To understand the need for a control valve we must go back to the principles of a vacuum system. Most steam heating system operators believe that the vacuum pump creates the vacuum in the system.  This is a misconception.  The condensing in the radiators produces most of the vacuum.  Additionally, the vacuum pump creates a differential pressure at the end of the condensate piping, aiding the flow of condensate out of the radiators back to the...