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Old 05-23-2020, 01:21 PM   #1
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1988 32' Excella
Vestal , New York
Join Date: Nov 2014
Posts: 12
polybutylene and pex piping

I'm installing a new hot water heater in my 1988 32' Excella and wondered if one could use pex interchangeably with polybutylene piping. It would be handy if it were so.

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Old 05-23-2020, 02:04 PM   #2
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2018 25' International
Slidell , Louisiana
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You can intermix the two, however polybutylene has a fairly short useful life. It begins deteriorating sometimes after just 15 years but generally more like 20-25. It has a nasty habit of deteriorating from the inside so you can't see that it is weakening without dismantling. Any that you can easily replace, you might consider it. PEX is superior, but I suspect you know this already....

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Old 05-23-2020, 02:05 PM   #3
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1994 34' Excella
Warren , Manitoba
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The ID is different between the Pex and the Poly. I have used a sharkbite connector to connect the two together. Pex connectors will NOT work!! If you check Home Depot, they have the special Sharkbite connetor. I re plumbed my H/W tank bypass and plumbing using pex and hooked to the poly. Easy to do!!
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Old 05-23-2020, 02:50 PM   #4
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1966 22' Safari
1955 22' Flying Cloud
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Dan, we just ordered connectors for Propex PEX tubing to PB (polybutylene) tubing. has the Sharkbites that allow connecting PEX to PB. We are switching out the hot water heater in a 1990 Excella to a Girard for a friend of ours. We will use the Whirsbo Uponor tool with the Propex tubing. The Sharkbite fittings from Supply House will also connect PB with your conventional PEX tubing. Weíre going this route because those are the tools we have and installed that system in both our trailers with no issues. Brian is right on with the PB deteriorating from the inside out. I have read it was the chlorine in the water that had adverse affects on the PB. Our friendís theory is to change out damaged areas to PEX as failed sections of the PB occurs. Hope this isnít too confusing. Good luck
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Old 05-23-2020, 02:58 PM   #5
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1988 25' Excella
1987 32' Excella
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I use the brass PEX fittings and the stainless steel clamp rings and have joined PB with PEX on many occasions with no leaks. Our PB fails in the fittings. The right angles just snap off where there is leverage on them. My advise is to put in as much PEX as you can get to when you do the job. And check that you have not inadvertently broken a PB fitting down the line. The only tricky thing I ran into on the WH was getting the gas line pulled out of the way to slide the heater in and out.
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Old 05-24-2020, 11:32 AM   #6
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1985 31' Excella
st. Paul , mn
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I've worked on a bunch of this , and if you can eliminate any / all of the polybutylene .
If you can not , next is avoid sharbite - it can easily "bite" you in the ass .
There are , and hard to find crimp adaptors for POY to PEX , I have found them at Home Depot's that were near mobile home parks .
And lastly , the best [ by far ] the crimps to use are the , dang can not recall - it was brand specific , crimps that used short pieces of PEX and the tools would stretch the PEX collar over the main PEX tubing & fitting , and now there is a couple of companies doing this .
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Old 05-24-2020, 06:09 PM   #7
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1989 25' Excella
Hershey , Pennsylvania
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I ran into problems with the Shark bite pex to polybutylene fittings. These fittings are designed to seal on the outside surface of the tubing. If there are any scratches on the surface of the tubing they can leak, maybe not at first but later on. I had two of these fittings that I used to splice new PEX plumbing into the existing PB lines. Both of these fittings started leaking the following camping season. I tried tightening them while on the trip but couldn't get them to stop leaking. After we got home I took them apart and found that the surface of the polybutylene had slight scratches that were the source of the leaks. I replaced them with the pex to PB crimp fittings referenced by Bill M and John TF. Have had no problems with the connections since making this change. Good luck with your project.
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Old 05-24-2020, 07:40 PM   #8
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1984 34.5' Airstream 345
Franklin Park , Illinois
Join Date: Jan 2015
Posts: 175
I just got done using shark bite and pex
I had two leaking original drain valves and so far NO leaks.. But I havenít gone camping with it yet Iíve been (for the lack of a better word) feverishly working on my 345 motorhome for the last two months fixing everything I can
This was a WAY more expensive fix then I originally anticipated but so far no leaks but again Iíve only had it under pressure for 48 hours and the RV has NOT gone over 10 miles since my plumbing repairs
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Old 05-26-2020, 09:09 PM   #9
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1966 24' Tradewind
1995 34' Excella
Lynchburg , Virginia
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polybutylene and pex piping

I installed a lot of polybutylene back in the 90ís when I renovated some old homes. I preferred it over copper and cpvc. I always used copper fittings instead of plastic. Most of the problems with polybutylene piping leaking was when plastic fittings were used.

I have a 66 Tradewind that had copper originally. I replaced it all with Pex about 8 years ago.

I have a 95 34í with polybutylene and copper fittings. I wonít replace any of this piping unless I have a problem. If I have a problem, I will transition to Pex and use Pex for the repair. The photo below shows the plumbing under the kitchen sink.

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Old 05-26-2020, 09:34 PM   #10
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1972 31' Sovereign
cotati , California
Join Date: Apr 2020
Posts: 13
Just a couple of helpful hints for people deciding on pex. If you use the umpinor propex style pex with the expandable pipe and sleeve you get better water volume and pressure. (maybe people don't care so much in a trailer) If you go with the crimp style pex you will lose a lot of volume due to the orifice of the fittings being much smaller. The propex fittings I.D. is the same as the tubing. Also the propex plastic fittings are pretty good for 90s, tees, and couplings. Go brass when you are adapting to copper or threads.

If you're using the shark bite fittings, you will be able to push them together until both ends stop in the fitting. Generally, if you relax the pressure for a second and then try and push them together again, the pipe drives in a little further.

Good Luck,

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