Two years ago I replaced my submersible deep well pump with a Gould 1 1/2hp. and everything worked fine. The pump is at 120 feet and the water level is at 80 feet. Beginning a couple of weeks ago we started getting a lot of blasts of air for a few seconds when we turn on the hot water faucet. This doesn't happen with the cold water only the hot. What's going on? Is it possibly my water heater?