What should you check if one zone in a house is not getting heat?

When one zone in a house is not receiving heat, checking the end switch contact on the flow switch is critical. The end switch is part of the zone control system, and its primary function is to signal the boiler or heating system to activate when there is a demand for heat in that specific zone. If the end switch is not functioning properly or is stuck in the open or closed position, the flow switch may not signal the boiler to start, resulting in that zone not receiving heat.

This process is crucial because it directly affects the operation of the heating system, specifically for zoned heating setups. A malfunction here means that even if everything else in the system is working correctly, that specific zone will be unable to get the necessary hot water or air to achieve the desired temperature.

Checking the thermostat settings, boiler pressure, or duct insulation, while relevant in other contexts, do not directly address the immediate operational issue of the zone control system not activating the heating. Therefore, verifying the functionality of the end switch is the most direct and effective step to take when diagnosing why that particular zone isn't heating.