No way to do PEX to tub spout?

[ShadowAviator]

I understand that PEX is not recommended due to the smaller ID when going to the tub spout.

Depending on the pressure this can push water up to shower head, plus just a lower flow rate to the tub in general.

I have seen where some people have suggested using 3/4 PEX to the tub spout. I believe this requires adapting to 3/4 PEX then back to 1/2 pipe for the spout itself.

However, these suggestions were also not recommended by the more experienced plumbers. They said really the only way was with copper or brass pipe.

I would think the ID of a 3/4 PEX fitting would be roughly 1/2".

My question is why would 3/4 PEX NOT work? I mean it may be simpler and even cheaper to use copper, but if someone really just wanted to use 3/4" PEX to a drop ear elbow then 1/2" brass nipple off that, would that work?

What am I not thinking of?

P.S. My bathroom is shower only ( with simple shower head), so I can do PEX there. I am just curious about if I ever had to go to a tub spout.

 

[Terry]

Any restriction to the tub spout is going to push water up to the shower head. I have some video I shot of that on a repair I went out to in Seattle. I had to remove the wall behind the tub for the repair. I removed the PEX fittings and the problem was solved.

It's in all of the instructions if people are willing to pull them out and read them. It's really simple too. If you have a valve that solders to copper, you pull the cartridge and solder in the pipe. You have to solder those valves anyway.

If you have a threaded valve, then a brass nipple and 90 works fine. Even easier.

PEX fittings reduce down in size to fit inside the pipe. It's a pretty tight squeeze. Even if you eventually put a piece of 3/4" there, you start with 1/2" and end with 1/2".

Are you just trolling people to see if you can trick them into making a mistake on their bath remodels?

Here it's copper to the drop ear and then a brass nipple for the Delta tub spout.

 

[Sponsor]

 

[Reach4]

Apollo APXDET12 or EPXDET12 (F1960) looks interesting, and would seem to overcome the concerns, while using only 1/2 inch pex plus a 1/2 inch brass nipple to the spout. Use two elbows or a long (180 degree) sweep to direct the water up to the showerhead. Alternatively, use one elbow from the valve and another up to the shower.

A pex twin el with the drop ears would be the ultimate, but no such thing yet.

 

[ShadowAviator]

Oh come on Terry, you know me better than that. I don't want to trick anyone. I think copper or brass is the way I would do it.

My question was not to convince people to use pex; it was to help me understand. (I am no plumber so I am assuming my thinking is not correct)

My thought was that you wouldn't need to start and end with 1/2" pex fittings.

If you have a 1/2" threaded port on the valve, couldn't you put a 1/2"MIP x 3/4" pex fitting in there? I think the ID would stay very similar throughout the fitting. I believe you can even get drop ear elbows that way as well.

I am not suggesting this as the right way to do it, I am just curious if it would work.

To clarify, I guess the question I should have asked is "Does the pex pipe itself cause any problems, or is it just the fact the fittings ID are usually too small for a tub spout?"

My main reason for asking is that I had someone ask me this, and I didn't really have a good answer other than "the pros recommend copper"

 

[Jadnashua]

What is important is the through hole through the fittings. The ID of a fitting will depend on whether you're using an expansion fitting, or a crimp one. The crimp one will be smaller than the ID of the tubing. So, if the ID of a 3/4" to 1/2" fitting is at least as large as the ID of a 1/2" copper or brass pipe/fitting, it will probably work...if it isn't, it won't!

Note though, that pex will offer little to no support for the tub spout, and that by itself, should be a reason to not use it. You want something rigid to hold the spout and pex, regardless of the size and fittings used, is not that.

 

[ShadowAviator]

I wondered about the sturdiness, too.

If you used those elbows that you screw to some sort of blocking, would that hold the spout rigid enough?

I would want to use something like that even with copper or brass. I could see people using the spout as a foot rest or something. Anything children height is subject to damage as well.

 

[Terry]

I just got back from a customer and her story was this.

Her daughter has been to this plumbing forum, and when she installed a new tub she noticed that the plumber had run PEX to the tub spout. Based on her reading of this plumbing forum, she asked him to change it to copper. He refused and told here it wasn't a problem.

The tile guy comes, so nice new tile everywhere, and then the plumber comes out to set the trim. When the faucet is running it's pushing water up to the shower head, just like she thought it would. But the plumber didn't believe that a woman could know those things. She did.

His fix was to come back another day and put a valve on the shower arm to prevent the dripping. So now every time she wants to just fill the tub, the valve at the shower head needs to be closed off.

Delta, Kohler, Moen and others all say in their instructions that you can't run PEX to the tub spout. However if you throw instructions away, and don't ever read them, then everything you touch is done wrong. There are some installers out there that swear that it's just bad luck when they screw up.

Wow! I didn't see that one coming.
Huh! Who wudda thought?
Really, but I like running PEX to everything.
Yeah, the fitting and the pipe is smaller but...................
What do engineers know?

PEX is really nice, but it's not for everything. And reading instructions can be fun too. I wish they made them easier to read for me though. Sometimes I have to take my phone out, take a picture and then read them off my phone.

Which way flows more water here? I'm going with the manufactures instructions and running copper to the tub spout.

 

[Jeff H Young]

for most of us sweating a 90 is easy enough but if you want to try a 3/4 inch PEX go for it but I still wouldn't try it just to much trouble if it doesn't work proper . waste of time.
But ill be honest I wondered as well . just not too interested in doing PEX 3/4 or even 1 inch . its not the pros that recommend copper its the manufacture requirement

 

[ShadowAviator]

I had a longer reply typed out, but maybe its best to just end the discussion here.

Again, I am not recommending anyone should use pex to go to the tub spout.

If I needed to do it myself, I also would not use pex, but rather probably brass.

The point I just wanted to discuss is that as long as the fittings you used did not reduce the inside diameter more than it would be on copper or brass pipe, then in THEORY, pex could be used as long as the final brass/copper stubout for the the spout was well secured.

The fittings I was thinking of were these:

https://www.homedepot.com/p/SharkBi...s-Reducing-Adapter-Fitting-UC138LFA/202270593

https://www.homedepot.com/p/SharkBi...ree-Drop-Ear-Elbow-Fitting-UC342LFA/204492219

I would want to measure these for myself to make sure but I would guess the ID of both fittings is similar to a 1/2" brass nipple.

Anyway, it seems the answer is: Pex MIGHT be made to work, but is the poorest solution and should not be used.

Terry, I apologize if it sounded like I was challenging the wisdom of professional plumbers or the manufacturers recommendation. I guess I was just curious if pex could be made to work. It was more of a thought challenge than something I would actually do. I appreciate your input on the matter, though.

 

[Jeff H Young]

Hey its a legit question . Since I never inspected the fittings and dont run PEX I dont know. But I wondered the samething about going bigger with PEX if it would work. I just wondered about it to myself though. But i think up all kinds of experaments that I don't take time to try. no reason why if all the passages are as big with smooth transitions or bigger than copper tube it should work. or if your going Tub only no shower no prob!

 

[Gsmith22]

given a fork in the road, water will travel in the direction that is least restrictive. And it won't all just flow down one fork, you will get flow on both sides of the fork but more will go to the side that is least restrictive. In terms of what is least restrictive, its not necessarily the pipe diameter, the fitting diameter, the elevation of the shower head, elevation of the tub spout, water pressure, or flow rate - it is all of those things to varying degrees. This is basically a study in the balance of the Bernoulli Equation. Without a dissertation on the Bernoulli equation, there probably isn't a succinct answer that can be given. That being said, I'm sure there is a situation somewhere where pex to the tub spout could work but it probably requires a unique set of circumstances that 99.9% of plumbers won't, can't, or aren't being paid to recognize. But copper to the tub spout always works so that is the defacto recommendation.

 

[Ron Oh!]

Hey there Shadow Aviator. Thank you! I’m so glad you thought of possibly using the 3/4” pex from the valve to the spout. I’m surprised that some other home repairs using 1/2” pex worked fine for me but the current one spewed water from the shower head anytime water was full force. I would have had to tear out a lot of tile and cement board to sweat copper inside the wall. Yes! The 3/4” pex has a huge inside diameter and so did the 3/4” drop ear and 3/4” barb to 1/2 FIP. I will use copper from now on, but this saved the day very well!

 

[Jeff H Young]

Hey there Shadow Aviator. Thank you! I’m so glad you thought of possibly using the 3/4” pex from the valve to the spout. I’m surprised that some other home repairs using 1/2” pex worked fine for me but the current one spewed water from the shower head anytime water was full force. I would have had to tear out a lot of tile and cement board to sweat copper inside the wall. Yes! The 3/4” pex has a huge inside diameter and so did the 3/4” drop ear and 3/4” barb to 1/2 FIP. I will use copper from now on, but this saved the day very well!

So the manufactures were correct dont use pex ? kinda figured but didnt want to proove them right and I really dont run pex unless Im working for someone that has a n expander

 

[Ron Oh!]

So the manufactures were correct dont use pex ? kinda figured but didnt want to proove them right and I really dont run pex unless Im working for someone that has a n expander

Yes, manufacturer is right, use copper. The 3/4” pex will work but it took 8 days to get the fittings from two different sellers and they were more expensive than readily available copper fittings. Sorry to have done the experiment! Lol.

 

[Reach4]

Yes, manufacturer is right, use copper. The 3/4” pex will work but it took 8 days to get the fittings from two different sellers and they were more expensive than readily available copper fittings. Sorry to have done the experiment! Lol.

If you feel like experimenting again, I am confident that my proposal in #3 would work without showerhead dribble. Not that it would not take a week to get the Apollo part, and it brings up the chore of getting the right-length brass nipple or equivalent. However that method needs some wood for that to screw into, and copper is self-supporting. The copper can be conveniently cut to length after the finished wall is up if the appropriate spout is used.

 

[Curiousv]

I just got back from a customer and her story was this.

Her daughter has been to this plumbing forum, and when she installed a new tub she noticed that the plumber had run PEX to the tub spout. Based on her reading of this plumbing forum, she asked him to change it to copper. He refused and told here it wasn't a problem.

The tile guy comes, so nice new tile everywhere, and then the plumber comes out to set the trim. When the faucet is running it's pushing water up to the shower head, just like she thought it would. But the plumber didn't believe that a woman could know those things. She did.

His fix was to come back another day and put a valve on the shower arm to prevent the dripping. So now every time she wants to just fill the tub, the valve at the shower head needs to be closed off.

Delta, Kohler, Moen and others all say in their instructions that you can't run PEX to the tub spout. However if you throw instructions away, and don't ever read them, then everything you touch is done wrong. There are some installers out there that swear that it's just bad luck when they screw up.

Wow! I didn't see that one coming.
Huh! Who wudda thought?
Really, but I like running PEX to everything.
Yeah, the fitting and the pipe is smaller but...................
What do engineers know?

PEX is really nice, but it's not for everything. And reading instructions can be fun too. I wish they made them easier to read for me though. Sometimes I have to take my phone out, take a picture and then read them off my phone.

Which way flows more water here? I'm going with the manufactures instructions and running copper to the tub spout.

So @Terry just confirming is it ok to use 1/2 PEX between valve and shower head ?

 

[Terry]

So @Terry just confirming is it ok to use 1/2 PEX between valve and shower head ?

Yes, the shower head has water being diverted up there anyway, and PEX gives you plenty of volume for that.

 

[Curiousv]

Yes, the shower head has water being diverted up there anyway, and PEX gives you plenty of volume for that.

I know you must have answered this before - but can you connect brass female threaded PEX fitting/adapter on galvanized pipe also how about bronze fitting on galvanized pipe? @Terry

 

[Tuttles Revenge]

So @Terry just confirming is it ok to use 1/2 PEX between valve and shower head ?

You've asked this same question on this forum in at least 3 different threads. Repeatedly asking won't yeild a different answer.

 

[Tuttles Revenge]

I know you must have answered this before - but can you connect brass female threaded PEX fitting/adapter on galvanized pipe also how about bronze fitting on galvanized pipe? @Terry

Yes, you can thread brass or bronze fittings onto steel pipe or into steel fittings. The two different metals are similar enough to not cause corrosion. In my experience its better to thread into the fittings than to try and use old pipe threads as pipe threads tend to be thinner and wear out faster.