Arrived on site to diagnose insufficient heating and one zone not working. After our initial inspection, we found that the water feeder to the boiler was shut off and was not supplying the boiler with water. The zone that was not operating properly was air bound. We purged the air from the zone and now it is heating properly. Part of the reason for insufficient heating could also be due to the boxes and furniture blocking the baseboards. There is also no wall between the garage and the living room. This is definitely allowing cold air to infiltrate. Recommended that they try to move some boxes and furniture away from the baseboards to allow more heat to transfer to the space. The boiler is also from 1987 and mentioned that they should be thinking about replacement soon.