Hot Tub Plumbing

Hot Tub Plumbing Methods

RATING: ADVANCED

The concept of joining PVC pipe involves welding the material together by using glue that actually melts the plastic parts to each other. In truth, each joint will have an area that is slightly tighter than the rest. In the tightest parts, this welding actually occurs. In the remainder, the glue bonds to each surface and itself becomes the bonding agent. Obviously the strongest part of each joint is the welded portion; but in either case, the key is to use enough glue to ensure total coverage of the surfaces to be joined.

Following is the correct procedure for plumbing with PVC:

1. Cut and Fit Cut and dry-fit all joints and plumbing planned. It is easy to make mistakes in measuring or cutting, and sometimes fittings are not uniform, so they don't fit well. Dry fitting ensures the job is right before gluing. If you need the fitting and pipe to line up exactly for alignment with other parts, make a line on the fitting and pipe with a marker when dry fitting so you have a reference when you glue them together.

2. Sand Lightly sand the pipe and inside the fittings so they are free of burrs. The slightly rough surface will also help the glue adhere better.

3. Prime You might need to apply a preparation material, called primer, to the areas to be joined before gluing. Some PVC glues are solvent/glue combinations, and no primer is required. In some states, however, use of primer might be required by the building code, so check that before selecting an all-in-one product. If you are using primer, apply it, with the swab provided, to both the pipe and the inside of the fitting. Read and follow the directions on the can.

4. Glue Before gluing, be ready to fit the components together quickly because PVC glue sets up in 5 to 10 seconds. Apply glue to the pipe and to the inside of the fitting.

5. Join Fit the pipe and fitting together, duplicating your dry fit, and twist about a half turn to help distribute the glue evenly, realigning the lines drawn on the pipe and on the fitting. If you are using flexible PVC, because it is made by coiling a thin piece of material and bonding it together, do not twist it clockwise. This can make the material swell and push the pipe out of the fitting. Get in the habit of twisting all pipe counterclockwise (even though it makes no difference with rigid PVC), and you will never make that mistake.

6. Seal With rigid PVC, hold the joint together about 1 minute to ensure a tight fit; about 2 minutes with flex PVC. Although the joint will hold the required working pressure in a few minutes (and long before the glue is totally dry), allow overnight drying before running water through the pipe to be sure. I have seen demonstrations with some products (notably Pool-Tite solvent/glue) where the gluing was done underwater, put immediately under pressure, and held just fine. I don't, however, recommend this procedure as I have gone back on too many plumbing jobs to fix leaks a few weeks later because I hastily fired up the system after allowing only a few minutes of drying time.

TRICKS OF THE TRADE: PVC PLUMBING

1. Make all threaded connections first, so if you crack one while tightening, it can be easily removed. Then glue the remaining joints to the threaded work.

2. When cutting PVC pipe, hacksaw blades of 12 teeth per inch (per 2.5 centimeters) are best, particularly if the pipe is wet (as when making an on-site repair). Finer blades will clog with soggy, plastic particles and stop cutting. Use blades of 10 inches (25 centimeters) in length. They wobble less than 12- or 18-inch blades during cutting. In all cases, the key is a fresh, sharp blade. For the few pennies involved, change blades in your saw frequently rather than hacking away with dull blades—you'll notice the difference immediately.

3. No matter how careful you are, you will drip some glue on the area or on yourself. That's why I always carry a supply of dry, clean rags to keep myself, the work area, and the customer's equipment clean of glue.

4. Try to make as many free joints as possible first. By that I mean the joints that do not require an exact angle or that are not attached to equipment or existing plumbing. The free joints are those that you can easily redo if you make a mistake. Do the hard ones Last—those that commit your work to the equipment or existing plumbing and cannot be undone without cutting out the entire thing and starting over.

5. Use as much glue as you need to be sure there is enough in the joint. It's easier to wipe off excess glue than to discover that a small portion of the joint has no glue and leaks.

6. Practice. PVC pipe and fittings are relatively cheap, so make several practice joints and test them for leaks in the shop before working on someone's equipment in tight quarters in the field.

7. Flexible PVC is the same as rigid, but when you insert the pipe into a fitting, hold it in place for a minute or longer because flex PVC has a habit of backing out somewhat, causing leaks.

8. In cold weather, more time is required to obtain a pressure-tight joint, so be patient and hold each joint together longer before going on to the next.

9. Bring extra fittings and pipe to each job site. Bring extras of the types you expect to use, as well as types you don't expect to use, because you just might need them. Nothing is worse than completing a difficult plumbing job and being short just one fitting, or needing to cut out some of your work and not having the fittings or a few feet of pipe to replace them. It is often several miles back to the office or the nearest hardware store to grab that extra fitting that should have been in your truck in the first place. Bring extra glue, sandpaper, and rags, too.

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