How Long Does It Take For An Electric Hot Water Heater To Heat 40 Gallons?

It takes on average an hour for an electric water heater to heat 40 gallons of water. I guess there is still problem with the heater even after the replacement of heating element. Get it checked from the services company.

I replaced a hot water heater and still no hot water its been 4 hours

When you say completely drained, do you mean out of water? After changing elements in a hot water heater, you must fill the water heater back up, open the faucets to purge the water heater and pipes of all air before you apply power. I did not do this the first time I replaced a lower element and I turned the water back on, the water filled the tank( so I thought) but when the water stopped filling, it only filled to just bellow the top element because of all the air in the system. I was only getting lukewarm at best. Found out later that the top element had burnt out because it was not submerged in water while I waited for the water to heat up.

If I replaced my bottom element and filled the tank letting out all the air, one should I replace to the top element?? Second how long does it take to warm the water?  Should my water heater make any sound??