All heating systems have to have a balance of pressure in order to work properly. In forced air systems, the air flow has to be balanced throughout the ductwork in order for the right volume of air to reach your living spaces; in a boiler, or hydronic, system, the water pressure has to be maintained in order for the system to work properly. Pressure imbalances can cause low heating, no heat or even a shutdown of the system. One way your boiler is able to balance its pressure is with the help of a component called the expansion tank.
What It Is
The expansion tank is a relatively small metal tank attached to your boiler system. It’s usually about head-high and is about 30% smaller than a gas grill fuel tank. The inside of the expansion tank is divided into two sections by a rubber diaphragm: the half attached to the boiler via a pipe is the water side and the other side is the air side. When the boilers starts a new cycle, a great deal of water pressure develops as a result of heating the water; the expansion tank helps balance this excess pressure by allowing water to enter the water side of the tank as it heats. Once the cycle is finished, most of the water forced into the expansion tank due to the heating process returns to the boiler for the next cycle.
How Does This Help?
Without the expansion tank, the water pressure in your boiler would not stay balanced, causing the pressure to go too high. Home boilers should not have an inner pressure higher than 15psi, and ensuring this is a large part of what the expansion tank does. Should the pressure increase to 30psi or higher, or the temperature of the water become hotter than 250 degrees, an additional safety mechanism called the expansion valve will open on an emergency basis and allow the excess water pressure to release.
Should problems develop with the expansion valve on your boiler, it will require an expert to first drain the tank and then re-fill the tank with the appropriate amount of air to regain system balance. If you are having pressure issues with your boiler, call the experts at Switzerland Air today. We provide expert boiler repair and maintenance services in the Freeport area.