Air in Water Line

[Stuart]

I have a new construction condo with a gas water heater. I have owned this for about 4 months and have been having air in the water lines. The air is most evident in the hot water side. When the hot water reaches the faucet the air is expelled. This is a recurring problem.

I would like to have an idea what would cause this.

Stuart Adams

[LazyPup]

The Standard Atmospheric Pressure is 14.69psi while the code minimum for residential water pressure is 35psi, or nearly twice the atmospheric pressure. This means that it is a technical impossibility for air to get sucked into the water lines as long as the supply pressure is present.

If you have a shallow well with an above ground pump the intake side of the pump is operating at a negative pressure (Below Standard Atmospheric Pressure) therefore if you have a crack in a line or a loose fitting air could be getting sucked into the intake then being pushed through the pump and pressure tank into the distribution system.

If you are on a municipal supply you should contact your service provider and have them check for the presence of air in the mains.

[Stuart]

Thanks Lazypup,

But is it possible that the hot water heater could be malfunctioning?

Stuart Adams

[LazyPup]

It is definitely not coming from the water heater. Here again, the internal pressure of a water heater is equal to the applied pressure from the water source. Given that the internal pressure is 2 to 3 times greater than the air pressure surrounding the tank any opening would result in water leaking out, not air going in.

Theoretically if a water heater were heated too hot it could produce steam which could leave the illusion of air in a line, but even if there was steam in a water heater that steam would immediate condense back to water when it goes through the water lines and begins cooling. In addition, the boiling temperature of a liquid is proportional to the pressure. While water boils at 212degF at standard atmospheric pressure at 35psi the boiling point of water is approximately 240degF and at the code maximum of 85psi the boiling temp of water is over 300degF

For that reason all water heaters are required to have a TPRV (Temperature/pressure relief valve) which is preset to disharge at 210degF or 150psi.