How to Install a Shower Valve Cartridge

The leaky Delta Monitor Series 1300/1400 shower valve cartridge has been removed. Next I’ll clean the shower valve threads and install a new shower cartridge, bonnet nut and sleeve O-ring.

This project is continued from How to Remove a Leaky Shower Valve Cartridge.

Clean the Shower Valve Bonnet Nut

The bonnet nut holds the cartridge in the shower valve body so the water pressure doesn’t pop out the cartridge. This bonnet nut is 12 years old with mineral deposits and copper oxidation (greenish/blue color).  The threads must be cleaned if the nut is to be reused so it doesn’t get frozen to the shower valve body making it difficult to remove for future maintenance.

Old Delta Shower Valve Bonnet Nut RP22734

Old Delta Shower Valve Bonnet Nut RP22734

I ordered a new Delta bonnet nut model # RP22734 along with the new Delta cartridge model # RP19804 because the bonnet nut is inexpensive and I’ve occasionally had to saw off a stuck plumbing nut.

The corrosion on the old bonnet was easy to clean and polish with a wire brush and steel wool with 10 minutes of effort. Here’s the rehabilitated old nut with the new bonnet nut:

Old and New Delta Shower Valve Bonnet Nuts RP22734

Old and New Delta Shower Valve Bonnet Nuts RP22734

Clean the Shower Valve Body Threads

The gunk on the shower valve body threads cleaned up well with a wire brush. Also clean inside the end of the shower valve body and wipe off any residue:

Clean the Shower Valve Body Threads with Wire Brush

Clean the Shower Valve Body Threads with Wire Brush

I used a 4-in-1 Plumber’s Copper Pipe Brush but any soft wire brush will do the job.

How to Install a Shower Valve Cartridge

It’s important to install the new shower cartridge in the correct orientation. The Delta P19804 cartridge has “Hot Side” embossed on the side where the hot water pipe enters the shower valve body inside the wall. By convention the hot water pipe is on the left as you face the shower:

DELTA Shower Valve Cartridge RP19804 - Hot Side

DELTA Shower Valve Cartridge RP19804 – Hot Side

Install the new shower valve cartridge by orienting the Hot Side on the left and insert the cartridge straight into the brass shower valve body. Do not twist or turn the cartridge because you could inadvertently separate the blue lower housing from the white cartridge cap when the two legs begin to slide into the water inlet pockets in the shower valve body. If this should happen remove the cartridge and snap it back together with a 1/4 twist.

Install DELTA Shower Valve Cartridge RP19804

Install DELTA Shower Valve Cartridge RP19804

Notice the two V-shaped alignment notches on both sides of the white cartridge cap match that in shower valve body (see the following photo).

I ran into a minor problem here; the cartridge would not fully seat into the shower valve body because the O-ring at the base of the white cap (the O-ring is just above my thumb in the previous photo) has to be compressed for a water tight seal. It was impossible to push the cartridge in all the way in by hand against the O-ring. The small gap between the cartridge and valve body is noted by finger in this photo:

Shower Valve Cartridge Install - Alignment Notch

Shower Valve Cartridge Install – Alignment Notch

The bonnet nut has two purposes:

  1. To compress the shower cartridge cap O-ring.
    The bonnet nut compresses the O-ring as it’s tightened and will fully seat the cartridge in the shower valve body.
    It’s the O-ring that makes a water tight seal.
  2. To hold the cartridge in the brass shower valve body so the water pressure doesn’t blow out the cartridge.

With the V-notches in the cartridge aligned with the brass valve body, I threaded the replacement bonnet nut on by hand…

Install the Shower Valve Bonnet Nut

Install the Shower Valve Bonnet Nut

… and tightened the bonnet nut with the channel locks. This part was very easy and I could feel the shower cartridge O-ring compress. The nut “bottomed out” quickly when the cartridge was fully seated in the shower valve body. Do not over tighten the bonnet nut because it will crush the plastic flange of the cartridge cap:

Tighten the Shower Valve Bonnet Nut with Channel Locks

Tighten the Shower Valve Bonnet Nut with Channel Locks

Turn On the House Water Supply

Point the shower head in a direction where it won’t spray on the shower valve and check that the shower valve is shutoff. You can turn the valve using the the gray disc or temporarily set the shower handle over the brass cartridge stem. If using the shower handle, remove it so it doesn’t fall off.

Turn On the house main water supply and shutoff the faucets after the air in the pipes is flushed.

Feel around the shower valve and cartridge checking for water leaks. A flashlight helps to look inside the shower wall at the shower valve body and pipe connections.

Replace the Shower Valve Sleeve O-Ring

I ordered a replacement Delta shower sleeve O-ring Model # RP23336 as an optional repair item thinking I might as well replace any rubber parts that might degrade with age:

DELTA Shower Valve O-Ring RP23336

DELTA Shower Valve O-Ring RP23336

The sleeve O-ring just rolls on and off the brass shower valve body. The O-ring serves as a spacer for the trim sleeve and prevents water from wicking behind the wall:

Replace a Delta Shower Valve O-Ring Part # RP23336

Replace a Delta Shower Valve O-Ring Part # RP23336

Reinstall the Shower Valve Trim Sleeve and Escutcheon

Slip the trim sleeve over the shower valve and O-ring, then reattach the escutcheon with the two long screws:

Reinstall the Shower Valve Trim Sleeve and Escutcheon

Reinstall the Shower Valve Trim Sleeve and Escutcheon

The shower valve cartridge water temperature is adjusted in How to Adjust a Shower Valve Water Temperature.

I also take apart the old shower cartridge to see why it leaked.

Thanks,

Bob Jackson

 

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29 Responses to How to Install a Shower Valve Cartridge

  1. Jodi Wilkie May 24, 2015 at 4:17 pm #

    Thank you for the easy to follow instructions. For every issue I had you had as well and told what to do!!
    The hardest part was getting the plate open to turn off the water.
    Thank you again and again!!,

  2. Wally June 15, 2015 at 8:52 pm #

    Your step-by-step instructions are the clearest I’ve ever seen. Thank you for your thorough documenting of this task.

  3. Van Carpenter September 2, 2015 at 10:05 am #

    You made the job quite easy and I saved a lot of money. Became disgusted that the residue left INSIDE my pipes bringing water from our city supply is so ugly!!

  4. Joe Baca December 5, 2015 at 10:48 pm #

    I did this and had what seems like an unusual problem. It leaks around the stem area(makes it look like the handle is leaking). I took back the first one that did it and now the second does the same. Am I just getting defective cartridges or am I doing something wrong?

    I’m at a loss………..

    • Bob Jackson December 6, 2015 at 9:24 pm #

      It’s leaking around the main o-ring which is just above my thumb in this photo.

      The o-ring can leak if:
      * The new cartridge is longer than your original which will prevent it from fully seating in the shower valve body. Compare the new cartridge to your old one. Note the model RP19804 is shorter than the very similar looking RP46074.

      * The shower valve body interior is rough with mineral buildup. Clean the area where the o-ring seats inside the shower valve body and also the hot and cold water inlets where the small o-rings on the legs fit into.

      * The cartridge is not correctly oriented with the alignment notch.

      * The bonnet nut needs to be tightened a bit more, but check the issues above first.

      The cartridge should go in most of the way with maybe a 1/8 inch gap before screwing on the bonnet nut, which will fully seat the cartridge when tightened.

      Thanks,
      Bob

  5. Sissy December 13, 2015 at 9:03 pm #

    Replaced the cartridge to my shower. Now the shower doesn’t have hot water. It does get warm but not hot. The hot water to the rest of the bathroom is working.

  6. Shaun December 23, 2015 at 11:19 pm #

    Thank you so much for the instructions. I’m pretty sure I’ve done all the steps – or shower doesn’t leak anymore. However, when I turn the shower off it sounds like the pipes are making a couple of loud “thuds”. At first it was just the shower, but now the toilet and bathroom faucet do it as well.

    I tried flushing all the air out of pipes, but still hear that ” thud-thud”

    Any thoughts? Thanks!

    • Bob Jackson December 24, 2015 at 9:55 am #

      It’s caused by water hammer. It’s more noticeable if the pipes aren’t strapped down to the house framing giving the pipes more room to wiggle.

      A water hammer arrestor will fix the problem. The arrestor contains an air piston to absorb the water hammer shock (air is compressible where water is not).

      The SharkBite Water Hammer Arrestor is easy to install. It’s a push-to-connect fitting that requires no soldering. The arrestor can be installed in an accessible location, say in the basement where the pipes are exposed near the bathroom or under a bathroom sink. Install an arrestor on both the hot and cold water supply pipes.

      The SharkBite arrestor is available at home improvement stores and Amazon.com.

      There are less expensive solder-joint water hammer arrestors but you’ll need a torch and soldering skills to install those. Given the often cramped spaces next to wood framing using a torch can be hazardous.

  7. Nate December 27, 2015 at 1:25 pm #

    I can’t get the new cartridge to sit in fully (where the alignment notches are) to screw the cap back on. What can I do to fix this? Thanks so much for your instructions! Very helpful.

    • Bob Jackson December 27, 2015 at 6:52 pm #

      If the cartridge is sticking out only 1/8 inch like mine the bonnet nut will seat it.

      However, if the cartridge has 1/4 inch or more to go then lubricate the O-rings with Danco 80360 Waterproof Grease. It’s safe for potable (drinking) water systems such as faucets and according to Danco Mfg won’t harm the O-rings.

      If grease alone still doesn’t work try polishing the shower valve body interior and inlets with a round brass wire brush to remove mineral scale that may be causing the O-rings to catch, then grease the o-rings and try again. Use only a brass wire brush because steel will scratch the shower valve body.

  8. Phil January 18, 2016 at 8:25 pm #

    Hi,

    I installed a new Moen shower valve in a new bathroom. Because of my marginal competence and a tricky retrofit location (at the same height as the original house’s rim joist etc), I had to redo the brazes at the valve a handful of times. I seem to have cooked the cartridge–on at least one occasion I forgot to remove it until after the valve was hot. The cartridge looks perfect, but the tub faucet leaks, and (weirdly) the other bathroom’s water doesn’t get hot–the cooked valve seems to allow mixing of H & C, and (I assume) the pressure differential caused by the water heater or the extra distance traveled or whatever results in the cold polluting the hot instead of vice versa.

    Anyhow, I bought a new cartridge, a cartridge repair kit, and the appropriate grease. I’m guessing the new cartridge would solve the problem, but I’m wondering if the original cartridge just needs to be regreased. I imagine the grease might be the first thing to fail when subjected to the heat of brazing.

    Do you have any experience with this failure mode? I’m not sure where the grease might need to go. The cartridge is pretty different from your Delta, but of course the concept is the same. Thanks for any input!

    • Bob Jackson January 19, 2016 at 8:13 pm #

      Fortunately I’ve not the had the occasion to cook a shower valve cartridge. :-) When I installed a shower in my basement bathroom I used SharkBite push-connect fittings and soldered the other pipe joints together before installing. (Note: Only use SharkBite fittings in exposed locations, they’re great and highly reliable but who knows if the fittings will leak after 20 years? Best not to conceal the fittings behind drywall in case it ever needs to be replaced.)

      > the [cooked] cartridge looks perfect, but the tub faucet leaks, and
      > (weirdly) the other bathroom’s water doesn’t get hot–the cooked valve
      > seems to allow mixing of H & C [water]
      I’d throw away the cooked cartridge and install the new one because the o-rings and plastic components are likely heat damaged. See if that fixes the water temperature in the other bathroom, too.

  9. Tricia Wattenburger February 20, 2016 at 3:53 pm #

    We appreciate your article – my husband and I are trying to DIY a shower cartridge replacement. It seems we’ve properly replaced the cartridge – no leaks there- but now when we turn on the water supply we have a pretty good sized leak from the pipe behind the cartridge- where the casing attaches to the 4 pipes in the wall. Do you have a recommendation? Is there a sealer or something we can use?

    • Bob Jackson February 20, 2016 at 7:16 pm #

      If a shower valve pipe joint is leaking you should call a plumber. It may be possible to resolder the pipe joint but it’s probably going to cost not much more to replace the entire shower valve and receive a better guarantee. That way you’ll have piece of mind all joints are water tight. Hopefully an access panel can be cut in the drywall behind the shower to access the valve and pipes.

      > Is there a sealer or something we can use?
      JB Weld WaterWeld epoxy putty might be a temporary fix, the pipe joint should be dry and dirt free for best results. If you use WaterWeld and the leak continues you’ll have no choice but to replace the shower valve because it won’t be possible to resolder the pipe joint.


      Let me know what happens.

  10. Chloe February 23, 2016 at 12:21 pm #

    Thank you so much for great instructions. I swapped out my cartridge no problem. I decided to change out my brass trim for chrome. Delta ARA series. Still 1400 so everything marries up but the actual trim plate, which is supposed to twist on. It doesn’t catch the dog ears all the way and ultimately moves the backer plate out of position. I have a fiberglass shower so it appears the wall is not completely flat so the plate has too much of a gap, which would allow,water in.
    Any tricks to get this plate on?

    • Bob Jackson February 23, 2016 at 8:53 pm #

      You’re changing the shower trim to a Delta ARA Monitor 17 Series shower trim, correct? The Delta ARA 17 installation instructions states on Section 3 Trim Installation on page 6 to install the bracket (part #5, aka “backer plate”) over the cartridge body using two screws. Then twist the square escutcheon to engage the locking tabs (dog ears) and secure it with the set screw.

      > I have a fiberglass shower so it appears the wall is not completely flat
      > so the plate has too much of a gap, which would allow,water in.
      > Any tricks to get this plate on?
      The square escutcheon should have a foam gasket on back to seal it against the shower wall, similar to the white foam gasket on my round escutcheon. It’s hard to image the fiberglass shower wall would be terribly warped, so I think all that’s needed is to:
      * lay the palms of both hands flat on the square escutcheon
      * press firmly to compress the foam gasket while twisting it to engage the locking tabs (dog ears)
      * install the set screw

      You might want to lubricate the foam gasket with a drop of liquid dish soap so it slides on the shower wall without binding.

      If you’re still having problems try backing out the two bracket screws (part #5, aka “backer plate”) 1/16 inch because it might be recessed too far in. Twist on the escutcheon which should engage the locking tabs and compress the foam gasket against the shower wall so everything is wiggle free.

      Let me know which method works for you.

      Thanks,
      Bob

  11. Jesse W May 15, 2016 at 7:51 pm #

    Hello!

    First, thank you for your time and replying to all of the comments.
    I have read each one to make sure I would not comment or bother you with a repeat question.

    Unfortunately, I did not see my problem listed.

    I completely understand if you no longer answer these but thought I would give it a shot, anyways.

    I replaced a Delta Monitor 1400 series cartridge. The first one I bought would not fit all the way into the sleeve. When I tightened down the cuppler, the pressure would build up and leak.

    I took that one back. I got 2 – a 46074 (gray and white) and a 19804 (blue and white)

    After reading this, I am using 19804. (Still have the 46074).

    I installed that and tightened it. All steps were completed … When I turned the water supply on, from the main, I could not control it at the shower. The water would not turn off. The whole cartridge would just spin and not “catch”… The temperature would not even change.

    I have been at this going on 8 hours (AHH! haha) now and I am just STUCK.
    If all else fails, I know I will have to call someone in but I would really like to do this myself because I like to make it a learning opportunity.

    Ps. THANK YOU! Not only for this site, but for your time!

    • Bob Jackson May 17, 2016 at 11:22 am #

      Hi Jesse,
      Are you sure you have the correct replacement cartridge? The new cartridge must be identical.

      > The water would not turn off. The whole cartridge would just spin and not “catch”.
      It’s likely the new cartridge is not the correct fit. Take your old cartridge to the plumbing supply store to find the correct replacement unit.

  12. Gretchen Erie June 14, 2016 at 10:57 am #

    How do get lower valve—blue part out?

    • Bob Jackson June 15, 2016 at 11:23 am #

      The lower cartridge body (blue part) is often stuck due to years of mineral build-up around the o-rings. Put the cartridge cap back on try wiggling & pulling the cartridge out. Also see my advice dated April 12, 2015 to another homeowner with a stuck cartridge.

  13. David Wright August 28, 2016 at 12:30 pm #

    My problem is the set screw that holds the handle on is frozen in place. No amount of force budges it. Had a plumber in and they couldn’t get it off, suggested they would need to saw the handle off. Any tricks to remove the screw? I spent a week squirting WD-40 in to no effect. My other thought was trying to drill the screw out, but I’m not sure if I have the tools for that.

    Any help is greatly appreciated.

    Thanks!

    • Bob Jackson August 28, 2016 at 1:10 pm #

      My first thought is to use a damaged screw extractor (available at hardware stores) but I doubt the bits will fit deep enough in handle. You’d need a cordless drill/driver, too. So yeah, drilling out the screw is the best option. You’ll most likely need to replace the handle because the threads will probably be damaged in the process.

  14. Scott October 3, 2016 at 7:41 pm #

    Replaced the old cartridge, was definitely a bad cartridge, but I still have a drip from the shower head. Even with the main water turned on or off to the house, I have a drip coming out. Suggestions? If the shower is turned off I have a drip, if the main supply is off I still have a drip. Im thinking the pressure is to high. I can put my thumb over the shower head connection for a few seconds and when I remove it I can feel it shooting air and water out.

    • Bob Jackson October 4, 2016 at 6:25 pm #

      What make/model shower cartridge do you have? Is the new cartridge an exact replacement?

      The seat springs might be a little weak which would cause a incomplete seal against the inlet plate. Try another new cartridge. If the new cartridge doesn’t leak then the 1st replacement was bad. If you’re still having problems try stretching the seat springs a bit so they’re longer and press harder against the seats.

  15. Wayne Hicks October 23, 2016 at 2:29 pm #

    I have a 1300 series Delta tub valve leaking. I rebuilt the cartridge with new seats and springs. It still leaked so I put in a new RP19804 cartridge( the valve is original to the house- 20 to 25 years old) It is still leaking bout the same as when I started.

    Any ideas?

    Thanks

    • Bob Jackson October 23, 2016 at 5:32 pm #

      I think what’s happening is an O-ring on the cartridge leg isn’t sealing properly. Remove the cartridge and polish the cartridge interior with a brass wire brush to remove any rust and mineral scale inside the 20+ year shower valve body. Especially the hot and cold water inlets the cartridge legs fit into. Lubricate the cartridge O-rings with waterproof plumbers grease before re-installing. See my comment dated December 27, 2015 for a similar problem.

  16. Tim November 20, 2016 at 12:24 pm #

    My problem with the RP 19804 is: After replacing the springs, seals, etc. and greasing as per your posts, the faucet doesn’t leak….until….after a half hour, or more, a gush (small cupful) of water comes out of spout…then follows a single drip every 30 seconds…..then a steady drip every 30 seconds….seems to be a buildup of water resulting is sudden gush ?

    • Bob Jackson November 20, 2016 at 4:08 pm #

      Did you replace the entire cartridge and clean/polish the shower valve housing to remove all traces of rust and scale? My guess is an o-ring on the cartridge leg is leaking. A small bit of debris can cause a bad seal. It leaks internally, the pressure builds and overflows to the shower head.

      A lesser possibility is unusually high water pressure. The pressure gauge on my expansion tank reads 57 psi which is controlled via the pressure regulator on the main water line. I’d focus on polishing the shower valve housing before bothering the pressure regulator.

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