System was off on low water cut off, which means that there was air in the system. Possibly a leak under the slab, which would have drained it. We realize this because the water was shut off, which means that the automatic fill pressure reducing valve couldn’t fill. Quite a bit of water was missing out of the boiler. If there’s no leak, the boiler should’ve held the water it had. You may have to find someone that can find leaks in a slab. And it seems like the two different zones that the pumps are on both had water missing. So it may be more Went ahead and turned the water on bled the air out tested everything to make sure that the piping was getting hot and the return water was getting hot for both zones