Tricks of the trade: spa / hot tub Installations

6. Plumbing the Jets: A typical 11/2-inch (40-millimeter) plumbed jet fitting requires a hole in the shell of 2IA inches (57 millimeters) to accommodate the throat of the jet. Using your electric drill and a 21A-inch hole saw, cut holes for the jets in the locations marked. The jet body slides through the hole, and a nut on the back secures it in place. Be sure to use the gasket provided on the inside (the water side) of the fitting to prevent leaks. Tighten the nut with channel-lock pliers, applying enough force to tighten but not crack the plastic nut.

The other type of jet uses a jet body that is held against the exterior (back side) of the hot tub, while a threaded throat passes through the hole in the hot tub wall and screws into the body. Jet wrenches are provided by the makers of these jets for tightening. On the face of the throat you will find two holes. The wrench fits into these holes to grip the throat fitting. While holding the jet body (usually requiring a helper), tighten the throat fitting into the body. Use enough force to tighten the throat against the gasket for a watertight seal, but not so much that you crack the fitting. Make sure to install all jet fittings with the water plumbing below and the air plumbing on top.

Some manufacturers make micro jets, smaller versions of the 1%-inch (40-millimeter) standard jet, built to accept 1-inch (25-millimeter) PVC plumbing. These are most often used in jetted bathtubs, but some people prefer the microjet in combination with the standard jet because you can use more of the microjets with the same equipment than the standard units.

Whichever design of jet you use, be sure to buy the ones designed for thin-wall spas. Jets are also made with identical components for hot tubs, except that the threaded throat is several inches longer to accommodate the greater thickness of the wood as opposed to the thinner fiberglass or acrylic walls.

Using flex PVC and the plumbing techniques described previously, connect the jets. If you are using one pump, the return line that sends water through the jets should be diverted with a T fitting, sending one-half of the flow to one-half of the jets and the other half to the remaining jets. If instead the flow runs the length of the jets, the pressure will be extremely high for the first few and extremely low on the last one or two. By equally dividing the flow you avoid that problem. You might also use a threeport valve instead of a T fitting, so that you can equally divide the flow or divert all of it to one side or the other.

If the hot tub is large and more than one pump is being used, divide the number of jets into two groups and plumb the flow from each pump accordingly. Since one pump will circulate water through the filter and heater, plumb it with fewer jets. For example, if the hot tub has 10 jets, plumb the filter and heater pump with four jets and the unrestricted second pump with six jets.

In each case, cap the dead (terminal) ends of each jet line with 1.5 - inch (40-millimeter) PVC caps attached to a short length of flex PVC I as pipe. I prefer this method to inserting a 13/4-inch PVC plug into the jet, because if the plumbing needs to be changed for any reason, the pluging makes that side of the jet permanently inaccessible. If you do need to be use the other end of the jet that is capped, you can cut off the cap and calf glue on a slip coupling, plumbing anything on from there.

Connect the air side of the jets together. If the jets are to be turboigh charged from a blower, plumb them as the water side is, with a Tilly fitting or three-port valve between equal numbers of jets. Cap the dead ends as described previously.

If the jets will be aerated instead from the atmosphere, there are two choices. First, on the top of each jet is a 3/4-inch (19-millimeter) opening to accommodate a length of pipe that extends up to the lip ich f the hot tub, aerating each jet individually. The other choice is to glue these openings shut with the plugs provided and stub one or two common air lines to the lip of the hot tub. With this method, an air control fitting can be mounted in the lip of the hot tub to which the common air pipe is glued. This air control fitting allows the hot tub user to close off all air supply, resulting in a jet that moves only water, or the air supply can be opened for the desired amount of added aeration. If the hot tub has been constructed with one or more air blower rings, they will be provided with a 2- inch (50-millimeter) stub in which to glue the PVC pipe.

7. Testing: Before installing the hot tub, perform a leak test on the plumbing. If the hot tub is preplumbed, it is important to perform this test to be sure the factory did a good job and that nothing was damaged in transit. It is much easier to repair or replace the plumbing above ground than to wait until the unit is installed. Glue flex PVC into the T fittings or three-port valves, and run enough length to bend the pipe over the top of the hot tub. You will have one line for the main drain, one for the skimmer, one for the air ring, and one for the return water to the jets (or two if you have installed a two-pump system). Cut the PVC and tie the lengths above the top of the hot tub, then fill the hot tub with water. There should be no leaks before you set the hot tub in the ground. Let the water sit for an hour or more to be sure there are no slow leaks. Take care when filling not to wet the outside of the hot tub or the ground, making it difficult to observe any leaks. If you have the equipment, pressure-testing the hot tub is a good idea (and might be required by building codes in your area), although I have found that if the plumbing is done with care and the hot tub passes this simple fill-up test, it will not leak under pressure. When you are sure there are no leaks, drain the hot tub .

8. Setting Up: Set the hot tub in the ground, onto the deck and any other supports. Carefully lower the plumbed hot tub into the ground, using enough helpers to avoid dropping the unit or resting it on the fragile plumbing. If the hot tub is to be backfilled with sand, once the unit has been stabilized and secured, perform another leak test. This might seem redundant, but believe me it is easier to spend an extra hour at this point than to make repairs later that require excavating the sand to find the leaks. If you took my earlier advice and used supports, you won't need to leak-test at this point, because without the sand, you will be able to see if leaks are present once the job is complete.

9. Setting the Equipment: The equipment should be located as close to the the hot tub as possible to avoid pressure loss in the system and to avoid heat loss by running water through long pipe runs. The level of the equipment should be as near the water level of the hot tub as possible to avoid priming problems. Working with your sub-contractors, prepare the site with a concrete pad of adequate size to accommodate the equipment, leaving enough room between components to allow access for repairs or maintenance. If you need to provide your own equipment pad, follow the instructions in the section on foundations for hot tub installations. Complete the gas and electrical supply connections to the equipment, and plumb the components using the methods described in previous chapters.

10. Plumbing: Trench as needed to run plumbing and electrical lines between the equipment area and the hot tub. Plumb the equipment and hot tub stub-outs together. If there are long runs of above-ground pipe under a deck or in other exposed areas, wrap them with insulation to prevent heat loss. Special attention should be given to the blower lines to ensure that water doesn't travel back up the line into the electric motor. See the section concerning blowers for details. Before closing the trenches, connect any control devices or switches planned for the installation, such as air switch buttons with air hoses running to the equipment area through a pipe in the trench.

11. Electrical Requirements: Hot Tub / Spa Electrical Supply Guide (bottom of the page) describes requirements for portable spas, but they are good general rules of thumb for inground installations also (except that the equipment for inground units will probably always be hard-wired instead of relying on a plug-in equipment package and electrical receptacle)

Page 1  |  Page 2  |  Page 3  |  Page 4