Please help with adapting PEX tubing to Hunter polybutylene plumbing for under sink water filter

Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Trying to install an under-sink Pentek slimline filter canister to the cold water tubing that exists as installed by the factory. Obtained 1/2" pex tubing and push on fittings, but the factory installed grey tubing looks very slightly smaller than the 1/2" pex tubing, and when I disconnected it at one T-junction it has a molded bulbous end like the flared end of a brake line - see pics. Is there a way, (what kind of fittings) to adapt the two types to each other before I go and cut the tubing that was factory installed?
In another forum someone alerted me to Sharkbite fittings which are supposed to adapt PEX to poybutylene grey tubing, but another poster seemed to indicate that the polybutylene Hunter used was Quest tubing that may be different in diameter to other polybutylene tubing now available, and that company is out of business and Hunter switched to other suppliers.
Thanks. Ilan
 

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Levin

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Apr 7, 2007
163
Hunter 340 San Diego
My bet is that like my Hunter it is 3/8 tubing with 1/2 fittings. Consider using a Sharkbite 3/8 T with the 1/2 connector on the one side of the T. Might be easier.

Take care,
-Levin
 
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Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Thanks; checked it out and these couplings are not approved for polybutylene connections; the only ones that are are their couplings designed to connect polybutylene with PEX and they only come same size to same size. don't know why their other fittings such as the one you mentioned can't accept ploybutylene. Starting to think I may have to use a simple barbed stepdown connector and crimp it, but don't know if polybutylene will take a crimping ring and not eventually fail. I can't be the only guy who has installed a filter!
 
Mar 29, 2017
576
Hunter 30t 9805 littlecreek
Sharkbites work and hold just fine. But there so expensive at big box hardware stores. I bought 7 of them because not sure on size but they took 6 back even gave me $ bac on one I opened
 
Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Will the 1/2 work on the polybutylene on this boat? Can't tell its size till I cut it. The OD seems to be around 1/2 " but don't have a caliper to measure it on the boat.
 
Dec 25, 2000
5,703
Hunter Passage 42 Shelter Bay, WA
The OD seems to be around 1/2 " but don't have a caliper to measure it on the boat.
The Zurn PEX Qest on our boat is 1/2" OD. Unable to help with any kind of adapter for your situation. As an alternative, I use a PUR brand faucet filter for our cooking and drinking. No need here to filter water for washing and cleaning. Unable to detect any difference in look, taste or odor between filtered and water directly from the tank.
 
May 23, 2013
54
Hunter H42 Passage East Chicago and Hammond
Yes as stated above, unless you want to change over all the tubing to pex. Use shark-bite 3/8" Polybutyl fittings. Order from either amazon or big box store. I just had to fix my shower line.
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
I bought a PEX crimp tool to use the crimp rings and reduce the need for SharkBite fittings. The tool has more than paid for itself in dollars per connection. It would be hard to use in some areas. Still...
 
Jul 17, 2012
44
Hunter 36 AuGres MI
Hardware store has Shark fittings. One end is blue the other is amber. That’s all you need. Along with my sail boat I own a 87 Carver. I’ve had gray water lines break. Replace with blue pew. “Shark, one end blue, one end amber. Their made as replacement
 
Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Thanks for everyone's help. Now I'm going to cut things and do some damage with all the tools and couplings money can buy.
 
Dec 25, 2000
5,703
Hunter Passage 42 Shelter Bay, WA
I just had to fix my shower line.
Hmm. That's where we had our water leak when we took possession in 2002. Hot side fitting beneath the sit tub pan failed because it was improperly installed, originally, I think. Missing the SS lock washer and the tube blew out of the fitting. Lovely place to do the repair. One hand show after removing the lower 8D.:banghead:
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Pentek slimline filter canister
May I ask, what kind of connection does the filter have? Is they simple female pipe thread ports?

My boat has polybutylene plumbing, and uses Parker O Ring/Grab Ring Tube Fittings. I have had great success with these. I replaced some tubing using 1/2" O.D. LLDPE tubing. The fittings will work with any tubing as long as the O.D is standard. You can get a variety of fittings including connections to standard pipe threads.

If the tubing on your boat is 1/2" O.D. you can cut off those bulb ends and use the Parker fittings.

(I don't understand the reference to PEX here.)
 
Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Canister has 1/2" NPT female inlet and outlet holes.
Interesting; I've already purchased the Sharkbite fittings at Home Depot, but by your account these would fit the bill. If my plan fails, will try this out. Thanks for the info. Ilan
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Ilan, I strongly encourage you to forego the Sharkbite fittings (they are returnable) and look into the Parker fittings. They are great: inexpensive, easy, and reversible. I got mine through U.S. Plastics, and the price and service was excellent.

https://www.usplastic.com/search/de...ttings/Parker® O Ring_Grab Ring Tube Fittings

They have almost any fitting you can use. Here's the fitting for 1/2" NPTF to 1/2" tube:



https://www.usplastic.com/catalog/item.aspx?itemid=28168

$2.74 each.

I purchased a small inventory of these kind of fittings, including T's, unions, etc., along with 100' of LLDPE tubing, as I was "straightening out" a bit of plumbing mess. It's all good now.

I highly recommend buying a tool to cut the tubing. It's an inexpensive, razor-blade-plier affair, very effective.

I can't remember where I got mine, but it looks like this:

 
Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Is LLDPE same as LDPE? Found Grainger carries these fitting but not the tubing.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
I don't know. Are you shopping Grainger because you can visit in person? I have experienced great, fast service from U.S. Plastics; I bought the tubing and fittings there.

This thread has made me think about adding a water filter. :) I have just a strainer now.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Manufactured from 100% non-toxic ingredients, Tamco® RT-55D LLDPE is an excellent choice for drinking water, beverage and food applications.

  • Chemically inert
  • Chemical resistant
  • Lightweight & flexible
  • Impermeable to gases
  • Maximum Working Pressure @ 70°F: 125psi
  • Durometer hardness (shore D): 55 (98 shore A)
  • Vacuum rating: to 28" Hg
  • Temperature range: -50°F to 140°F
  • NSF 61 certified
  • Sold in full rolls only
100' roll is $20. Maximum temperature is marginal in my application, but I haven't had a problem yet, in almost 2 years of use.

It's quite liberating to have conquered the plumbing tubing issue on the boat. My previous boat had the reinforced nylon hose and barbed fittings, which I hated. The tubing gets hard, and it becomes tough to remove, and tough to re-seal. This LLDPE and Parker fittings will allow you to comfortably straighten out a lot of iffy plumbing issues, and easily enhance the system. It's also liberating to learn and understand how all of the fittings work, and how all of the components work. I have more to do: a tempering valve for the water heater output; an air vent on the pump output line; a drain for the over-pressure and temperature relief valve on the heater; re-commission the fresh water wash down tap in the anchor locker. Now I know how to do it.
 
Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Thanks; have an order in and see what fits. If does I thing is an excellent idea to stock up on fittings just in case. Ilan
 
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