I’d appreciate some geometry help

[bluedog225]

This is a fine mess I’ve gotten myself into. I’ve got 2” schedule 40 pvc running into the bottom of a concrete beam and into the garage with a tight 90 degree bend. It should have been a long bend. My fault for not double checking it years ago when this was poured.

The plan was to insert a three-quarter inch PEX line with a 90° Sharkbite fitting on it from the outside and then push a piece of pex down from the top. Tricky but doable.

Much to my surprise even as I type this, a 90° three-quarter inch Sharkbite will not fit inside a 2 inch PVC pipe. It’s just a bit too tall.

Interestingly, the 90° elbow outside diameter is large enough for this 90° Sharkbite fitting. One option is to smash all this PVC out of the concrete beam and leave a bare concrete hole which will work fine. Smashing out the PVC is going to be messy and take time. I’m tempted to take a roofing torch to it but I’ll save that idea for later.

And there are some other options for getting this done. But pushing the PEX through the bend may be easiest/best.

My question this morning is can I gently heat and bend the PEX to make this turn without kinking it. I have reached the limit of my ancient geometry memory. I wonder if you have any idea how to calculate this. The PEX bending radius is 10 times the pipe diameter. 10 times 0.75 is 7.5 inches.

The specific question is, what is the bend radius described with a 0.75” pipe running on the outside walls of a 2” pvc pipe with a sharp 90 degree coupling?

Many thanks.

 

[PugetDude]

I don't have a 2" PVC fitting to measure the height (figure it is roughly 1/4 of a diameter, work backwards to get an inside radius,) or to skip the math altogether just slice a fitting in half longitudinally and measure the radius... and see if your PEX is going to bend to fit...
You are going to have to figure the PEX bend through the neutral axis ( centerline, not inside or outside diameter).

I'd also see if a 90° 3/4 conduit El would slip through the 2" fitting, easy to adapt to whatever you need from there.

 

[mike93lx]

I'd just grab a stick of pex and try to shove it through. If it won't work, maybe step down to 1/2" for that part of the run?

 

[dave*99]

Would this work?

https://www.lowes.com/pd/SharkBite-3-4-in-Push-to-Connect-x-Push-to-Connect-dia-Repair-Hose-Push-Fitting/1000182603

There are similar options....for connecting water heaters.

 

[Innovate1]

I did a quick sketch for 7.5" radius. If you assume a short dwv bend the inside corner will be cut about the diameter of the PEX (maybe a bit less but just getting a rough idea if we are close to limits). It looks like you are right on the edge or likely just under 10x radius. If it is truely a sharp bend with no relief on the inside corner of the fitting its way under 10x.

That's a really tight turn either way. I did 2" 24" conduit sweeps for a 1" water line when doing my shop feed. Maybe you could get 2 45s to fit? If you remove the PVC I would be concerned with the concrete eating into the PEX with little movements of the PEX over time. Maybe slip a sleeve of Poly pipe over it for that.

 

[bluedog225]

Something like that might work. I’ll need to find what will fit to a pex/sharkbite fitting.

I will heat up a stick and shove it through and see what happens. Though I would like to know if I’m in the neighborhood of the appropriate bending radius.

I can switch to 1/2 and the sharkbite fitting will fit the existing 2” pipe.

 

[bluedog225]

Thanks Innovate! Looks like I’m (maybe) in the neighborhood.

I had not thought of joining two 45 degree fittings. I bet that will work.

Also, I might be able to ease the sharp corner of the fitting if I run something through there.

 

[Jim greengo]

I'd blow some jet line through there,then use it to pull the pex through without fittings.

 

[dave*99]

You could splice in a piece of 3/4 soft copper refrigeration line. Sweat PEX barbs onto it and crimp on the PEX. You would have to check diameters to be sure the copper tube mates to fittings.

 

[sizem]

Quick cad look shows max of slightly less than 4 inch radius. Only 1/2 inch pex would meet min radius bend.
Perhaps addt'l details would allow other insights/options.
Any chance to use the sch 40 pvc directly (i.e. transition pex to pvc and back to pex.
Good luck!

 

[bluedog225]

Interesting the different results.

Yes, I could use the pvc directly. Or maybe run a 3/4 pvc inside the 2” pvc.

The double 45 degree sharkbite may be a winner.

 

[TRWham]

Interesting the different results.

Yes, I could use the pvc directly. Or maybe run a 3/4 pvc inside the 2” pvc.

The double 45 degree sharkbite may be a winner.

Except I doubt you will be able to seat the Sharkbites fully if you are planning to push the PEX from any distance. It takes a bit of force so the pipe is liable to flex and misalign, and you will not be able to observe if it is fully inserted.

 

[TRWham]

You could splice in a piece of 3/4 soft copper refrigeration line. Sweat PEX barbs onto it and crimp on the PEX. You would have to check diameters to be sure the copper tube mates to fittings.

That would be called 7/8" in refrigeration.

 

[CraigStu]

I don't like the idea of bending the pex heat or not. Afraid long term abbrasion where it is in contact w/ the inside corner of the 2" pvc could leak eventually. Since you were thinking you could push pex down from above and into a sharkbite fitting I think I'd just skip the pex. Would a 90deg pvc fitting in maybe 1" fit inside the 2" pvc. If so, it would be super easy to just do a normal pvc cement joint like you were planning to do w/ the pex.

 

[housewolf]

I'd blow some jet line through there,then use it to pull the pex through without fittings.

That’s what I’d do, one person pulling, the other pushing

 

[bluedog225]

What is jet line? Like pull strap?

 

[rayra]

just as information and a lesson for others, why on earth are you shoving pex thru a 90deg PVC pipe joint embedded in concrete, in the first place? I ask with honest curiosity because it seems like an utterly asinine idea to me.

And how do you expect to feed said PEX past the pipe lip inside the coupling on the outbound part of the turn, presuming you can even initiate the turn while trying to shove a pex line into the turn in the first place.

Maybe I'm misinterpreting your drawings. Are those top-down drawings AND a conduit embedded inside of a cast concrete wall? Again I ask why would you do it that way.
Why isn't the pex just penetrating the wall instead of being embedded within it?

Again I'm asking the questions for edification, because of what I am taking to be your description and intent - to try and shove PEX WITH FITTINGS INSTALLED, around and thru a PVC conduit 90 DEGREE corner seems utterly impossible to me. As in a completely ridiculous plan. Fails in several 'best practice' with these materials. 90 degree turns in flow is suboptimal. As is treating PEX like it is copper pipe and adding a bunch of joint fittings mid-run. The entire point of the stuff - besides freeze resistance - is that it gets installed with continuous runs, the fewer fittings the better. Less fittings = less places for things to leak.
Yet here your plan is to abrade it, bend it, heat it, put multiple fittings on it, all in service of shoving it thru a 90deg conduit turn. Wrong thing on top of wrong thing on top of wrong thing. My brain is stuttering on the multiple Why?Why?Why? produced by your plans.

/maybe I'M wrong. Maybe I misunderstand your questions and intended course of action.

eta

presuming I've understood your layout and intentions correctly, what are you trying to accomplish? Hiding the pipe? 'armoring' it against abuse, while planning to abuse the hell out of it during the install?

If it is just a case of armoring or simply embedding - and it isn't already built yet - you ought to be using either electrical or sewage plastic conduit as your shrouding. With their large radius 'sweep' turns - which are meant for easier passages or pulling barely-flexible things thru turns.

There's just no way in hell you are going to pull a PEX water line thru a 90deg 2" PVC corner. Even the imagined 'bending' utilizing two 45deg pex connectors doesn't account for the fact that a long run of PEX has to enter and make that turn. Or that you can't assemble that PEX coupling mess INSIDE the pipe.

If it isn't yet built, you could conceivably piece the entire monstrosity together, building it by starting at that corner, but even if you could, to what end? You'd never be able to pull it thru or replace the pipe later. And isn't that the foundational purpose of the entire idea of sleeving a passage thru concrete with larger diameter conduit, so PEX can move freely thru it? So it CAN be pulled and replaced?

I think I'm belaboring my points at this point, but I will say it again - if this isn't already built, I strongly advise you to step back and reconsider the entire idea, right from the base premise of what you are trying to accomplish. And I say that having many years experience in building things, home remodeling and construction and working with PEX and all manner of conduits. Rethink what you are trying to do. Step back and look at the forest again.

 

[andyvh1959]

Can also heat the section of PEX in hot (not boiling) water and "pre-bend" it to the aprroximate radius. Let it cool, it'll flex enough to make the bend and retain the pre-bend shape once its in place. PEX tubing (blue or red) can withstand momentary hot water exposure at temps higher than we can sustain in the shower, as long as its not boiling. I did this to install PEX in some tight routing when I changed some plumbing for my main bath remod. That was back in 2018.

 

[rharman]

My vote would be to use the PVC directly with reducers/adapters as needed at each end.

Of course, we're assuming the PVC is water tight.

 

[PoorUB]

I would forget trying to run PEX in the 2"PVC, I don't see it happening. If you cut out the PVC somehow, then you will have a rough concrete finish, and a relatively sharp concrete 90 degree corner harder yet to pull and forever chaffing away on the PEX.

Run the line some other way, some other place. The 90 should have been an electrical sweep.

 

[Jim greengo]

That would be called 7/8" in refrigeration.

They make 3/4" o.d refrigeration line,as well as 7/8".

 

[TRWham]

They make 3/4" o.d refrigeration line,as well as 7/8".

Yes, but it is not the same size as 3/4" copper for plumbing, so it could not be used as described. The equivalent ACR tube size to 3/4 Type L or M plumbing pipe is 7/8.

 

[Youngandfree]

I'd cut the slab and replace the 90.

 

[Jim greengo]

Yes, but it is not the same size as 3/4" copper for plumbing, so it could not be used as described. The equivalent ACR tube size to 3/4 Type L or M plumbing pipe is 7/8.

Whatever gets it through there,you could always sweat a 7/8-3/4 reducer on the other end.
But I'd probably just stick with a bare piece of pex without an end on it with jet line tied to it,because copper doesn't bend around corners like pex will.

 

[PugetDude]

Here's another thought...
Bend a piece of 3/8 round bar into a 90°, if it will make the corner, slip a piece of PEX over it and push it through. Remove the bar and terminate the PEX.

 

[bluedog225]

It’s been fun looking for a solution. But I’ve spent about enough time on this.

I’m going to try to find a photo of the rebar layout and drill out a 1” hole through the concrete wall and run 3/4” copper up and through.

Thanks for helping problem solve.

 

[haveissues]

just as information and a lesson for others, why on earth are you shoving pex thru a 90deg PVC pipe joint embedded in concrete, in the first place? I ask with honest curiosity because it seems like an utterly asinine idea to me.

And how do you expect to feed said PEX past the pipe lip inside the coupling on the outbound part of the turn, presuming you can even initiate the turn while trying to shove a pex line into the turn in the first place.

Maybe I'm misinterpreting your drawings. Are those top-down drawings AND a conduit embedded inside of a cast concrete wall? Again I ask why would you do it that way.
Why isn't the pex just penetrating the wall instead of being embedded within it?

Again I'm asking the questions for edification, because of what I am taking to be your description and intent - to try and shove PEX WITH FITTINGS INSTALLED, around and thru a PVC conduit 90 DEGREE corner seems utterly impossible to me. As in a completely ridiculous plan. Fails in several 'best practice' with these materials. 90 degree turns in flow is suboptimal. As is treating PEX like it is copper pipe and adding a bunch of joint fittings mid-run. The entire point of the stuff - besides freeze resistance - is that it gets installed with continuous runs, the fewer fittings the better. Less fittings = less places for things to leak.
Yet here your plan is to abrade it, bend it, heat it, put multiple fittings on it, all in service of shoving it thru a 90deg conduit turn. Wrong thing on top of wrong thing on top of wrong thing. My brain is stuttering on the multiple Why?Why?Why? produced by your plans.

/maybe I'M wrong. Maybe I misunderstand your questions and intended course of action.

eta

presuming I've understood your layout and intentions correctly, what are you trying to accomplish? Hiding the pipe? 'armoring' it against abuse, while planning to abuse the hell out of it during the install?

If it is just a case of armoring or simply embedding - and it isn't already built yet - you ought to be using either electrical or sewage plastic conduit as your shrouding. With their large radius 'sweep' turns - which are meant for easier passages or pulling barely-flexible things thru turns.

There's just no way in hell you are going to pull a PEX water line thru a 90deg 2" PVC corner. Even the imagined 'bending' utilizing two 45deg pex connectors doesn't account for the fact that a long run of PEX has to enter and make that turn. Or that you can't assemble that PEX coupling mess INSIDE the pipe.

If it isn't yet built, you could conceivably piece the entire monstrosity together, building it by starting at that corner, but even if you could, to what end? You'd never be able to pull it thru or replace the pipe later. And isn't that the foundational purpose of the entire idea of sleeving a passage thru concrete with larger diameter conduit, so PEX can move freely thru it? So it CAN be pulled and replaced?

I think I'm belaboring my points at this point, but I will say it again - if this isn't already built, I strongly advise you to step back and reconsider the entire idea, right from the base premise of what you are trying to accomplish. And I say that having many years experience in building things, home remodeling and construction and working with PEX and all manner of conduits. Rethink what you are trying to do. Step back and look at the forest again.

The first sentence in his original post addresses 90% of your rant.

 

[bluedog225]

To wrap this up. I found that sharkbite make a 24” heater hose in 3/4”. It has a 5” bending radius and took the corner gracefully.

I can drain the entire plumbing system from the waste drain in this valve.

Thanks all.

edit-weird. The attachment isn’t attaching.

 

[bluedog225]

Trying again

 

[nadogail]

There are large radius 90 degree Sweeps that can accommodate the insertion of flexible pipes and hoses.

 

[PugetDude]

His 90° bend is already in concrete...

 

[rayra]

The first sentence in his original post addresses 90% of your rant.

It didn't do any such thing. All it did was state the reason for his dilemma. And mine wasn't a rant. It was an appropriate level of scorn for a bunch of unworkable ideas for trying to force anything thru that 90deg corner. A shame you don't understand the difference.

 

[bluedog225]

[deleted]

 

[Ryan]

just as information and a lesson for others, why on earth are you shoving pex thru a 90deg PVC pipe joint embedded in concrete, in the first place? I ask with honest curiosity because it seems like an utterly asinine idea to me.

And how do you expect to feed said PEX past the pipe lip inside the coupling on the outbound part of the turn, presuming you can even initiate the turn while trying to shove a pex line into the turn in the first place.

Maybe I'm misinterpreting your drawings. Are those top-down drawings AND a conduit embedded inside of a cast concrete wall? Again I ask why would you do it that way.
Why isn't the pex just penetrating the wall instead of being embedded within it?

Again I'm asking the questions for edification, because of what I am taking to be your description and intent - to try and shove PEX WITH FITTINGS INSTALLED, around and thru a PVC conduit 90 DEGREE corner seems utterly impossible to me. As in a completely ridiculous plan. Fails in several 'best practice' with these materials. 90 degree turns in flow is suboptimal. As is treating PEX like it is copper pipe and adding a bunch of joint fittings mid-run. The entire point of the stuff - besides freeze resistance - is that it gets installed with continuous runs, the fewer fittings the better. Less fittings = less places for things to leak.
Yet here your plan is to abrade it, bend it, heat it, put multiple fittings on it, all in service of shoving it thru a 90deg conduit turn. Wrong thing on top of wrong thing on top of wrong thing. My brain is stuttering on the multiple Why?Why?Why? produced by your plans.

/maybe I'M wrong. Maybe I misunderstand your questions and intended course of action.

eta

presuming I've understood your layout and intentions correctly, what are you trying to accomplish? Hiding the pipe? 'armoring' it against abuse, while planning to abuse the hell out of it during the install?

If it is just a case of armoring or simply embedding - and it isn't already built yet - you ought to be using either electrical or sewage plastic conduit as your shrouding. With their large radius 'sweep' turns - which are meant for easier passages or pulling barely-flexible things thru turns.

There's just no way in hell you are going to pull a PEX water line thru a 90deg 2" PVC corner. Even the imagined 'bending' utilizing two 45deg pex connectors doesn't account for the fact that a long run of PEX has to enter and make that turn. Or that you can't assemble that PEX coupling mess INSIDE the pipe.

If it isn't yet built, you could conceivably piece the entire monstrosity together, building it by starting at that corner, but even if you could, to what end? You'd never be able to pull it thru or replace the pipe later. And isn't that the foundational purpose of the entire idea of sleeving a passage thru concrete with larger diameter conduit, so PEX can move freely thru it? So it CAN be pulled and replaced?

I think I'm belaboring my points at this point, but I will say it again - if this isn't already built, I strongly advise you to step back and reconsider the entire idea, right from the base premise of what you are trying to accomplish. And I say that having many years experience in building things, home remodeling and construction and working with PEX and all manner of conduits. Rethink what you are trying to do. Step back and look at the forest again.

It didn't do any such thing. All it did was state the reason for his dilemma. And mine wasn't a rant. It was an appropriate level of scorn for a bunch of unworkable ideas for trying to force anything thru that 90deg corner. A shame you don't understand the difference.

Hey man... The Garage Journal is working hard to be a more friendly community - open to learning and teaching. I don't think this tone and way of communicating fits within that. If you can help someone - great!!! But please don't do it at the expense of degrading someone worse than they already have themselves.

In other words, be cool man. ****. We are all just getting along the best we can with what we got. And once everyone starts recognizing this, maybe then gratitude will come.