How Spa Jets Work

Consider a simple spa jet. Spa Jets have 3 main connections – water in, air in, and a water and air mixture outlet. The water is pushed into the jet by pressure from the pump and flows through and comes out the front. This is how the air gets mixed into the pressurized water stream that we will be discussing.

The air gets mixed into the pressurized water by use of a venturi inside the jet. The venturi effect happens at the tip of the orifice which is a small hole inside the jet that all the incoming water gets pushed through.

To understand the venturi effect you have to first understand the way fluid acts inside a pipe. If we reduce the size of a pipe with fluid moving through it, the velocity (speed) of the water increases, but the pressure in the pipe decreases. So if we have spa water flowing through a 2” pipe and we reduce the size to 1.5” for part of the run, the water in the 1.5” section moves faster but at a lower pressure.

If you look inside a spa jet they all have a reduction in the internal plumbing size, we call this reduced size section the “orifice”. The most common size of the hole in the orifice is 5/16” of an inch. This means that we reduce the incoming water feed that was lets say 1” pipe, and we force all this water through a hole just over a 1/4” wide.

This causes a section of the water to travel at a higher velocity and at a much lower pressure. This low pressure at the tip of the jet orifice is lower than the pressure of the air in the atmosphere outside. Since the outside air is a higher pressure than the water at the tip of the orifice, air gets pushed into the water stream at the tip of the orifice and mixed into the water. This water and air mixture then flows out of the front giving us the jet action we are all familiar with.

What goes wrong with Spa jets?

Most complaints about spa jets have to do with them no longer mixing air properly. Customers will report that the jets are “broken” or not working, they will also sometimes refer to the pump “not being as strong as it used to be”, or even talk about the air controls or the air blower being broken. Jet malfunctions usually lead to weak jets or jets with no air in them at all, but they can also lead to water shooting out of the air controls or a the jet sucking water in instead of blowing water out. Almost all jet problems are centered around the orifice. occasionally spa Venturi fitting will crack as a result of either deck or ground shifting or movement. It is often times necessary to saw cut and remove a small section of pool decking in order to access the pipe rupture work area. Once the plumbing is complete the work area can be backfilled and cemented. Ace Leak detection does not provide the pool deck topping such as acrylic, knock-down texture, cool-deck, Chattahoochee stone , stamped concrete or flagstone decks , etc. If you have a paver deck we will make an attempt to replace your pavers but will not guarantee paver work. Its best to call a paver company if this scenario presents itself. Sometimes it is nessecary to remove the entire spa jet from the wall which may compromise a small area of the pool finish. Usually a ring no larger 1” around the outside diameter of the fitting.

Ace Leak Detection charges $1,150.00 to replace a single spa venture fitting. process usually takes no longer then one day to complete depending on parts and availability.
After the repair is complete Ace Leak detection will pressure test the remaining spa therapy jets to make sure that there are no other leaking pipe fittings.