Checked the system. The circulators at the boiler were on. Numbered the Circ’s according to the zone panel. The area that had issues was the in-law apartment. It is a hydro air handler. The pipes were hot and the lower running. Found the air filter plugged. Removed the filter, the customer is going to replace it. Had 96* coming out of the register. Turned the thermostat off to check the operation. System is working properly.