Gas Fitter Practice Test

What should the relief valve for a residential low-pressure hot water boiler system be set to?

1. 14.7 psia

2. 15 psia

3. 30 psig

4. 30 psia

The correct answer is: 30 psig

The relief valve for a residential low-pressure hot water boiler system is appropriately set to 30 psig because this value allows for safe operation within a residential setting where the typical operating pressure does not exceed this threshold. The purpose of the relief valve is to prevent excessive pressure buildup in the system, which can occur due to overheating or other system failures. Setting the valve at 30 psig ensures that if the pressure surpasses this level, the valve will open and release excess pressure, thereby protecting the integrity of the boiler and the safety of the household. In most residential low-pressure hot water boiler systems, the operating pressure is designed to be below this relief valve setting, which provides a safety margin. It is not common for residential systems to operate at or exceed 30 psig during normal conditions, so the valve serves as an effective safeguard. The other options do not align with standard practices for residential hot water boiler relief valves. A setting of 14.7 psia refers to atmospheric pressure, and a setting of 15 psia would also be below the pressure typically required to safeguard the system. The setting of 30 psia would be inappropriate as it does not account for gauge pressure encountered in these systems. Hence, the 30 ps