Hot Tub Plumbing Tutorial

Commercial Hot Tub Plumbing

These are before and after pictures for the plumbing of a commercial hot tub. This job, typical of commercial and high rise construction, is being built inside of a recessed and waterproofed shell. The wood forms have been built to exact specifications according to the finished engineer drawings and health/safety code requirements. The insulation found on the floor (and later to be on the walls as well) serves the purpose of insulating the hot tub which will minimize heating costs.

This is a seven jet system with each jet being fed a high pressure water supply originating in 3" Diameter suction and return as well as a open air supply line. The air supply is not forced (under pressure) but instead allows air to freely occupy the space at the jet nozzle. The negative pressure introduced by the "hydro-air" jets creates a vacuum that inundates the air in with the high pressure water. The presence of this air is what creates the white and frothy jet blast and can generally be controlled via a regulator on the adjacent wall that allows or blocks the air from reaching the jet.



This system consists of the following:

-Circulation suction from main drains (2")
-Circulation suction from skimmer (2")
-Circulation return (1.5")

-Jet pump suction (3")
-Jet return (2.5")


The skimmer has an equalizer line that runs from the main drain to the rear port on the bottom of the skimmer. This is a MUST have feature on a commercial tub. Without this equalizing line the water level could easily drop below the mouth of the skimmer if excess water is splashed out or displaced. If this happens and there is no equalizer line the skimmer will gulp air and be noisy. If the pumps are located above the waterline grade this could also cause the pumps to lose their prime as the system is designed to be closed. This can have all sorts of negative consequences from burnt out pump motors to loss of function of the tub.

The equalizer line allows the suction of the system to access water so long as the water level stays higher than the bottom of the skimmer (which is about 2 feet below the standard water line)

For those with a good eye for detail there are a few pipes that do not terminate correctly yet. This is because the circulation return lines run the risk of being broken during the next stage of construction - steel grid application. The return lines are finished after the steel goes in. Generally the same day that you install the remainder of the return lines you will perform a pressure test to ensure that the system is 100% leak free before the concrete is applied.