Re: "Air in line" when hot water heater is on.
Posted by Sylvan Tieger on April 07, 2004 at 15:03:29:
In response to Re: "Air in line" when hot water heater is on.
: Ever since I had the hot water heater replaced about a year ago, I seem to have air in the line when I turn on the hot water (does not happen with cold water or with the "hot" water when water heater is off and has been off for a few days.)The water sputters for the first 5 minutes or so then is ok. This is a vacant rental property and there have been times when the water heater has been off for a couple of weeks at a time.

All fresh water contains oxygen and it can and does bubble off in a hot water tank/boiler etc.

Because this tank is seldom used the water giving up these bubbles (Oxygen)
Creates a dangerous condition.

You may want to consider having a Hoffman 78 or 79 installed to remove this air from the system

Here is the reasoning behind removing air from the system if your interested in the "technical" aspects.

Water does compress (ever so slightly) BUT air does this is the reasoning for the duel ratings of a T&P valve.

As air is compressed it can create dangerous pressures.

Ever pop a water balloon NOTHING happens it plops open that is why we hydrostatic test pressure vessels and boilers (ASME section IV and NBBI)

Ever pop a balloon with air, vast difference huh?

This is the National Board of Boiler inspectors check for proper air removal of closed systems.

If you want even more details feel free to contact me

Under normal conditions the hot water is used daily but when allowed to stand an explosive condition can develop that is why you either shut off the h/w heater when not in use Or run a little water every few days Or install the Hoffman to protect the system.

Replies to this post