I had a Heil furnace installed in my basement with a direct vent outside the basement wall. Without using the chimney connection, now my hot water heater is constantly going out when the furnace blower comes on. Any suggestions?

The vent for the new furnace must exit the house separately, so they did that right. Can't use the chimney as a vent for a 90+ furnace. Other than that, I would suggest having the installer back to see what is causing the problem. Could be not enough combustion air(or is combustion air piped outside too?), or the return ductwork is pulling too much air from the utility room.