There is air coming from the shower head because the water system isnt pressurized and the air is coming in there right when you turn off the shower. You need to pressurize your system. Hope this helps. Thank you
YOU MUST HAVE A PRESSURE REDUCING VALVE ON MAIN WATER LIE COMING IN TO YOUR HOUSE WRITE… IT MUST BE GETTING WHORE OUT… IT’S CAUSING AN AIR SWIRLE, INSIDE WATER PIPE AND TRAVELING TO WATER HEATER; CAUSING AIR IN THE TANK’’’ PIEPER PLUMBING 303-585-0877
I would assume that you have a tub/shower combo unit. If so, everytime you finish using the shower head option the water will drain back out of the tub spout. This is a normal design of most fixtures. So now the pipe leading up to your shower head is empty. When you turn your faucet on, the water will have to travel back up the pipe leading to your shower head. Doing so, it is pushing air ahead of it as it is coming up the pipe to your shower head. This typically only last for about 1 second or less. It is totally normal for this to happen with this type of shower/tub application.
If you have a shower only unit (no tub), the pipe behind the wall may have a small hole in it causing the water to drain out after every use. This would then allow air to fill the pipe. So when you turn the faucet on, it’s pushing air ahead of the water. At this point you would need a licensed plumber to come in and fix this problem. If the problem goes unresolved, you may have extensive damage done to your structural integrity of your house.
I hope this information has helped you.
Sincerely
David Deaton
Deaton’s Construction