How a HYDRONIC BOILER SYSTEM  works

Hydronic means that the pipes that heat the home are filled with water. The heat, that the water absorbed from the boiler, is usually moved around a home via a ciculation pump. There could be several different pumps that handle different "zones" of the home. There are a few basic principals of science that need to be understood, regarding how a boiler system heats a home.

In this explanation, we are first going to talk about the water side of a boiler system, and talk about a few laws of physics while we walk through a boiler system.

In this explanation, we will consider the main source of water to be water that is provided to our system from the city.  Simply put, we have a water supply that the city provides and is not from a private well system.
 
City water usually comes into a home at 30-50 PSI. In a residential boiler system, the maxium allowable working pressure (MAWP) is 50 PSI. So if the water were to just be piped into a boiler's water heating piping system, the MAWP could be exceeded already. This could be a very bad thing. So we come to our very first control part on a boiler: It is a pressure reducing valve.