What is the typical setting for a low temperature limit or primary control at a boiler?

The typical setting for the low temperature limit or primary control at a boiler is commonly set at around 140° F. This setting is important for ensuring that the boiler operates efficiently while preventing issues such as condensation within the exhaust flue or on the heat exchanger surfaces, which can lead to corrosion and reduce the lifespan of the equipment.

Maintaining this temperature helps ensure adequate heating without risking the condensation of moisture, which can occur at lower temperatures. By setting the low temperature limit at 140° F, the system is also able to provide enough heat for comfort heating applications while avoiding problems associated with lower operating temperatures.

This standard is widely accepted in the HVAC industry, as it balances safety, efficiency, and longevity of boiler systems. In contrast, other temperatures listed would either be too low or too high for the typical low temperature limit setting, which could compromise system performance or lead to other operational issues.