I recently had a direct vent furnace installed. It replaced an old one that went into my chimney which is brick with a clay liner. My hot water heater is currently the only appliance going into the chimney. It enters the chimney above where the furnace used to enter. The installer patched the chimney by stuffing newspaper into the hole and then putting a coat of mortar over it. Is this right? It doesn't seem to me like it is a good idea to put newspaper at the bottom of a chimney. Is there a better way to make the modification?