What could be a sign of low water levels in a hydronic heating system?

A constant operation of the pressure relief valve is a clear indication of low water levels in a hydronic heating system. When water levels drop below a certain threshold, the system can become susceptible to overheating. This overheating can lead to increased pressure within the boiler, triggering the pressure relief valve to open and release excess steam or water to prevent a dangerous buildup. Consequently, if the pressure relief valve is frequently activating, it suggests that the system is not maintaining proper water levels, which can cause inefficiencies in heating and could potentially result in damage to the system.

In contrast, while increased water temperature, heating elements running continuously, and unusual noises from the boiler can indicate various issues within a heating system, they are not definitive signs of low water levels. Increased water temperature might occur due to other factors such as thermostat settings, and heating elements running continuously can be a symptom of a system trying to compensate for heat loss or inadequate insulation. Unusual noises could stem from a variety of mechanical issues or air trapped in the system. Thus, the key sign linked specifically to low water levels is the consistent operation of the pressure relief valve.