The optimal pressure for a boiler depends on the model and the number of floors in your home. In general, the usual cold pressure of a boiler should sit at about 12 psi (pounds per square inch) . Most pressure gauges display different-colored zones, and the ideal boiler pressure is often marked as a range in green on the gauge itself. When the unit fires up the heat, the pressure should rise to around 20 psi while the heating element is operational, which is still in the normal pressure range. Pressure changes of a few psi one way or the other can be brought about by atmospheric conditions. Most boilers are safe up to around 30 psi, at which point seals can begin to fail. However, the maximum pressure the boiler should ever see is stamped on the boiler tag, usually 30 or 50 psi.

Exceptions to the optimal psi range mentioned previously are for homes with two to three stories, where the boiler should run at upward of 15-18 psi. If you find that your boiler pressure is dropping further than you would like, it’s likely that a leak has occurred.

In summary, the optimal pressure for a boiler is usually around 12 psi, but its important to consult the manual that came with your boiler to find the optimal pressures for your specific model. If youve lost the manual, a professional can determine the optimal range of your boiler by its model.