How to Replace a Dishwasher – install a new PVC P-trap for the dishwasher drain hose for easy clean-out and turn on the new dishwasher. This project is continued from How to Replace a Dishwasher – Part 6.

The dishwasher drain line is connected to the garbage disposal fitting or PVC drain pipe, according to which method matches your situation. The dishwasher drain line enters from behind the cabinet at the top left of this photo and is fastened to a 3/4″ PVC pipe with the metal band clamp:

Dishwasher Drain Line Connection to House Plumbing

The dishwasher installation is completed by:

  1. Turn on the water supply valve under the sink.
  2. Check all water connections for leaks. Tighten the connections as needed.
  3. Turn on the dishwasher circuit breaker.
  4. Run the dishwasher.
  5. Check the drain line connection for leaks.
  6. Reinstall the dishwasher toekick access panel.

Am I done? But nooo! I’m a perfectionist and it irritated me when troubleshooting the drainage problem on my old dishwasher that I couldn’t easily check the PVC P-trap for clogs.

Dishwasher Drain Pipe P-Trap Replacement

These steps are completely optional and won’t apply to most installations, especially so if your dishwasher drain line connects to the garbage disposal.

The new P-trap with Union by Charlotte Pipe has a threaded nut to disassemble and clean the trap. The parts list is:

  1. P-trap with Union, cost is about $8 at Home Depot
  2. 1-1/2″ to 3/4″ bushing
  3. 1-1/2″ repair coupling
  4. 1-1/2″ by 3 foot length of PVC Schedule 40 pipe (not shown)
  5. 3/4″ by 3 foot length of PVC Schedule 40 pipe (not shown)
Dishwasher Plumbing: PVC P-Trap with Union - Charlotte Pipe Part #708P

Dishwasher Plumbing: PVC P-Trap with Union – Charlotte Pipe Part #708P

Replace the Dishwasher Drain P-Trap

PVC pipe is wonderfully easy to cut and glue. I began the P-trap replacement by sawing off the 1-1/2″ PVC drain pipe at a convenient place about 6″ from the wye. This isn’t something you see everyday.

Dishwasher Drain Plumbing: Saw Off the PVC Drain Pipe

Dishwasher Drain Plumbing: Saw Off the PVC Drain Pipe

Sawn off section of PVC drain pipe plumbing – this will be thrown in the trash:

P-Trap and Plumbing Pipe Section Sawn Off

I purchased a 3 foot section of 1-1/2″ PVC pipe at Home Depot. The replacement section is marked with a blue line near the middle for cutting. I just eyeballed where to make the cut because precision isn’t necessary here.

1-1/2″ by 3′ Schedule 40 PVC Pipe

The shortened section of pipe and the repair coupling are ready to be primed and glued. Remember to deburr the ends after all saw cuts. The PVC Purple Primer stains badly and the newspapers are needed to catch any drips.

Replacement Section of 1-1/2″ Drain Pipe

The replacement section of 1-1/2″ pipe is glued to the house plumbing as seen in the background of this next photo. Now I’m ready to assemble the new P-trap, bushing and 3/4″ PVC pipe.

Do not prime or glue the threads of the union and nut.

Dishwasher Drain Plumbing: PVC P-Trap with Union, Bushing and 3/4" Pipe

Dishwasher Drain Plumbing: PVC P-Trap with Union, Bushing and 3/4″ Pipe

The various joints are primed. The 3/4″ pipe, bushing and P-trap are glued together.

Dishwasher Drain Plumbing: New P-Trap Assembly

Dishwasher Drain Plumbing: New P-Trap Assembly

The P-trap elbow is glued to the end of the PVC drain pipe (center back of photo).

P-Trap Ready for Final Assembly with the Dishwasher Drain Hose

I fastened the dishwasher drain hose to the 3/4″ PVC pipe nipple first because it was easy to reach. The exterior diameter of 3/4″ PVC pipe is about 1″ and fits the 1″ molded end of the dishwasher drain hose snugly.

Dishwasher Drain Hose Clamped to the P-Trap Assembly

The P-trap is screwed to the union using the captive nut by hand – no tools necessary. If I ever suspect a clogged P-trap it will be easy to remove and clean.

Dishwasher Drain Line Connection to House Plumbing

Dishwasher Installation – Final Steps

Repeating the final steps that were presented in the “short story” version above:

  1. Turn on the water supply valve under the sink.
  2. Check all water connections for leaks – no leaks found.
  3. Turn on the dishwasher circuit breaker.
  4. Ran the dishwasher.
  5. Check the drain line connection for leaks – no leaks found.
  6. Reinstall the dishwasher toekick access panel.

Dishwasher Installation Complete!

We’ve had the new Frigidaire Gallery dishwasher for a month and it’s working great! My wife is very pleased. My opinions about the dishwasher are:

  • It’s runs whisper quiet.
  • The dishes are very clean and dry.
  • The dry cycle runs hot – almost too hot to touch the plates and glasses immediately after. This is noted in the “Use and Care” manual. Once I noticed a faint smoke and acrid odor coming from the top of the dishwasher during the dry cycle. I opened door and found the plastic top to a sports bottle had fallen onto the heating element in the bottom of the tub, melting it.

Frigidaire Gallery Dishwasher Model FGHD2433KF1

Update: Do not Buy!

The dishwasher worked fine for 18 months until the circulation pump failed just 6 months after the 1 year manufacturer warranty expired.

Thanks for reading,

Bob Jackson

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