Ever since plumbing was invented, air-locks have always been a
problem. It's the reason why vents exist in the drain plumbing in your home, and why small
vent valves are sometimes provided in strategic locations in your spa plumbing, and your
In this first section, we'll take a look at one of the most common spa
air lock problems, it's one that plagues about 40% of all spas in use today.
Why does it exist? Because the pump wet end is rotated so that
the discharge goes out sideways, instead of straight up. If it went up, in virtually all
cases, the air lock would never exist because the air, will go up and out of the pump on its
own. Also, even if it still existed downline, the pump would be able to develop enough
pressure to force all of the air out.
What I do in this case is to run the pump on LOW speed, and slightly
open one or more of the small air vents until a small amount of water flow is noticed, and is
constant. What will also help this, is to close the heater discharge valve, on the other side
of the heater, forcing ALL of the air out. I don't do this for very long, because leaks can
develop under this kind of pressure.