Making PEX and PB play well together

[perryg114]

I have PEX in my trailer and the parts that have not been rigged I plan to leave for the time being. However, the bathroom water heater area has a combination of Reinforced Tygon (Clear with Nylon Braiding), PEX, and PB(polybutylene). These are all connected together with hose barbs and hose clamps. I believe that PEX and PB are pretty similar as far as OD and ID, which means I should be able to use the PEX pinch clamps for the PB side. I just repaired a leak to the shower valve by blocking the T's off with 1/2" NPT femal caps. As luck would have it, the PB compression T uses 1/2" NPT threads on it for the B-nut threads. The T is for 3/8" ID PB tubing that has an OD of 1/2". Which according to the specs of PEX the OD and ID are the same as PB. The PB fitting failed because it had tension on the tubing for a long period of time eventually causing it the crack. The other end of the fitting had an NPT thread. The PB to NPT fittings made of PB seem to be the weakest. The PB-PB connections all look sound. I did not see any breakdown of the PB tubing.

So what I plan to do is run PEX out of the water heater using brass PEX-NPT adapters and then a PEX coupler between the PB and PEX tubing. I will probably replace the PB T's that are now plugged off with PEX brass T's and then run PEX to the shower valve again with brass PEX-NPT fittings. Ok how many folks have I lost here.

I know I should bite the bullet and replace everything with PEX. I might have to rip the whole trailer apart to do that and it is not worth it at this time. If I remodel the bathroom I will address it again. It seems like all the plumbing from the pump comes in under the shower (center bath) and there are T's up under there.

Perry

[danlehosky]

Perry, PEX is cross braided polyethelene which has a memory. This is why it will work so well with the barb fittings. I'm not sure about the other stuff.

Have you thought about replacing ALL of the piping in the WH area with PEX while you have the tools out. It's cheap and a very, very good product.

Adios,
Dan

[perryg114]

Yes when I get back from camping this weekend I am going to seriously think about replacing the water heater stuff with PEX but I will have to interface with the PB at some point. PB uses a very similar type barb fitting with pinch clamps similar to PEX.

Perry

[Thalweg]

I've used these PB to PEX fittings several times. I've bought them at Home Depot and Ace Hardware. They make pretty simple work of the project. You do need a PEX crimper though.

[Steve Bryant]

Perry,
I feel your pain! When I re-plumb my trailer later this fall, it will likely have to be a hybrid system like you describe. I know that I will re-do the complete bathroom and as much of the kitchen and fresh water tank as possible. I don't know sometimes where to start and where to stop and I can't do everything that I think needs to be done to the nth degree. I think that's what your wrestling with.

[perryg114]

Thanks for that info. The problem is finding these things once you are in the store. You ask someone at the store and you get the deer in headlights look. There must be some differences in the ID/OD of the two pipe systems.

Perry

Originally Posted by Thalweg

I've used these PB to PEX fittings several times. I've bought them at Home Depot and Ace Hardware. They make pretty simple work of the project. You do need a PEX crimper though.

[perryg114]

I would replace anything that is PB to NPT like the shower valve. My kitchen sink looks ok but the bathroom is a mess. Yes Steve you hit the nail on the head. You can't replace everything and make it better than it was from the factory and still work two jobs and get it done in less than a year's time. She is better than she was a year ago. Most of the structural stuff is done, now it is time to work the details.

Perry

Originally Posted by Steve Bryant

Perry,
I feel your pain! When I re-plumb my trailer later this fall, it will likely have to be a hybrid system like you describe. I know that I will re-do the complete bathroom and as much of the kitchen and fresh water tank as possible. I don't know sometimes where to start and where to stop and I can't do everything that I think needs to be done to the nth degree. I think that's what your wrestling with.

[Kevin245]

Originally Posted by perryg114

There must be some differences in the ID/OD of the two pipe systems.

Perry

We're currently installing pex in our rig as copper was just too costly. I inherited a box of pex/pex, and pb/pex crimp fittings and they are very close to the same diameter. The difference is in the number of the raised annular rings that serve as barbs on the fitting. The pb side has more rings than the pex side, and IIRC the pb side of the fitting is a slightly greater OD.

I will post some photographs this evening.

[Bill M.]

I use the PEX and the brass PEX fittings and the stainless steel crimp rings. Works fine to connect PB to PEX. At least I think so. I have several PEX to PB connections and they have been fine for a couple of years.

[Crusty]

I used brass fittings to interface between PB and PEX and it's all leak free a couple of years afterwards.

FWIW, at Lowes you can find a different sort of crimp clamp for PEX and the associated crimper is much cheaper than the copper ring crimper. The ring crimper can be rented at Home Depot but still the size of it makes it very difficult to get into some locations and your crimp will always be suspect (in your mind at least) because everything wasn't perfectly aligned when you squeezed. The Lowes crimper is much smaller and easier to fit in tight locations.

[Melody Ranch]

I USE SHARK BITE FITTINGS TO SWITCH FROM PEX TO POLY TUBING AND BARBED FITTINGS. I ONLY DO THIS WHEN I CAN'T USE SHARK BITE ON THE WHOLE JOB. I USE SHARK BITE INSTEAD OF PEX CRIMPS DUE TO TIGHT WORKING AREAS. (sorry for the caps....I'm trying to learn to use this new (to Me) MAC wireless keyboard.)

[Frank's Trailer Works]

I strongly suggest you use just one system. Mixing a bunch of different types of plumbing is just asking for troubles. Pick a system and go with that. I know many have spoken of what they use, so I will state mine.
I use blue PEX for cold and red for hot. I use the pro grade copper rings as opposed to the pinch style stainless ones. I have used hundreds and hundreds of these type connections and have NEVER had a single one leak(GODS TRUTH!). Because the fittings twist after crimped, I can make a very long run on the shop floor and easily snake it under and around. I have literally gone all the way around a 30 footer by snaking it under and around. I find this system to virtually idiot proof. I fancy the saying, make it idiot proof and they will make a bigger idiot...
I have used the SeaTech plastic quick connects in the past and they are NEVER allowed in my shop as a result of numerous failures. I have also used the brass version made by SharkBite. They are extremely convenient, but I have had issues with them also.

on a side note;
Many of the older Airstreams used refrigerant copper instead of the normal plumbing type. This changes the inside diameter over to outside diameter and makes finding fittings very difficult unless you go to a refrigerant supply house.

[Melody Ranch]

Do what Frank said. One kind.

[BAB]

I got chills when I saw the initials "PB". My VERY EXPENSIVE home in Del Mar, CA was plumbed with PB....and of course, later there was a class action lawsuit over PB. Turned out that after some indeterminate time, the crimpings had some kind of chemical reaction and the PB would weaken until water emerged. All of the piping was in the ceiling with runs going through the walls to all the fixtures. Once you had an "incident" you were eligible for TOTAL replacement of all the PB with copper. You can imagine the cost, and mess of drywall repair, etc., etc. I would NEVER EVER have anything to do with PB. Since the issue had to do with the crimping process (the crimp process is nothing like PEX...I have done a lot of work with PEX and have never had a single issue with it). Tough part with PEX is the space it takes to close that enormous tool you use to tighten the crimp ring. I don't know about PB/PEX relationships. I just would have nothing to do with it. Ever!

[overlander63]

Sea Tech makes push-together fittings for PEX. You can use that in areas you can't get the big honkin' tool in to use.
And I'm with Frank. Pick a type of plumbing material, and stick with it.

[M2HB]

PB is one of the worst plumbing systems ever invented. I would change out all PB t PEX. I need to do my entire Avion 34' trailer.

[perryg114]

There is very little difference in PB and PEX. The tubing is similar and the fittings are similar as well. PEX built on the PB technology. I am going to start fixing stuff with PEX with the end goal of it all being PEX at some point. I am not going to gut my trailer just to put PEX in. My trailer will not be hooked to city water 100% of the time or even a fraction of that. It is not going to be exposed to pressure and fresh Chlorine for extended periods. Folks that use Sharkbite or similar fittings are going to get bit by the shark sooner or later as well as anyone who used plastic PEX connectors.

Perry

[Frank's Trailer Works]

I deleted my post three times now. I will leave it at just the one sentence.

Why did you ask for advice if you already had your mind made up?

[perryg114]

Frank I never said you were wrong in what you said. I don't like the PB being in there but it is not cost or time effective to replace all of it right now. My goal is to actually camp in my trailer as opposed to worship it like it is a silver twinky god. I believe you do good work and I think you know what you are doing. Just because I don't agree with you does not mean that what you are saying is not valid. My post was about how do I make reliable connections to PEX to fix the worst of my plumbing nightmares. I agree that PB is a problem. The concept was a good one but the material was not good. PEX is the next evolution of what was started with PB. My goals are different than yours. There was nothing wrong with your original post and there was some good info in there. You having a different opinion does not bother me why does mine bother you?

Perry

[M2HB]

The reason I suggest that all PB be changed out is that PB and PEX are not the same. PB was involved on one of the most expensive litigations over product failure, ever. It cost people billions of dollars in damage. In homes, where the water purveyor clorinates their water, PB will last about 7 years and then it will start breaking. If you can't replace all your PB, just understand that you will eventually have to.
My 1988 Avion 34' trailer has PB and when I get around to it, I will replace all of it. I won't have a choice if I want to use it.