1/2" or 3/4" PEX?

[BigBeakie]

I'm a bit confused on this discussion of 3/8th & 1/2 inch PEX. I just went and bought some Sharkbite Pex tubing and fittings. Also got some SmartX fittings from Bunnings to compare.

They only have 16mm ( which they call 1/2 inch) tube & 20mm ( called 3/4) tube O.D. The I.D. of these is 12mm for the 16mm OD so that is effectively half inch. But the fittings for the 16mm tube only have an ID of 9.5mm, which is 3/8 inch.

So which measurement is everyone referring to? The internal diameter of the tubing, or the internal diameter of the 16mm tubing?


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[kmacdonald]

Tube is measured by outside diameter and pipe is measured by inside diameter.
PEX tubing sizes are denoted by CTS (copper tubing size), not OD (Outside Diameter) or ID (Inside Diameter)

[KP44]

Depends upon your fresh water supply. Even in my land dwellings I use 1/2' for hot water lines to cut down substantially on the time and water wasted waiting for hot water. On the boat I would never go above 1/2" for hot. Pex is great stuff.

[Bigjim]

Originally Posted by Hoodsail

Just installed 1/2 inch red and blue pex into my boat with two sinks, 10 gal hot water heater and two fresh water tanks. Would recommend you chose your water filter first as that will drive your pump pressure. If you use the push to fit pex, these require leverage to securely seal so beware of using in hard to reach areas. They are expensive but can be taken apart and reused. Worst part is getting to difficult to reach areas. Good luck.

What type of water heater did you choose?

Water filter?

[Bigjim]

Originally Posted by BigBeakie

I'm a bit confused on this discussion of 3/8th & 1/2 inch PEX. I just went and bought some Sharkbite Pex tubing and fittings. Also got some SmartX fittings from Bunnings to compare.

They only have 16mm ( which they call 1/2 inch) tube & 20mm ( called 3/4) tube O.D. The I.D. of these is 12mm for the 16mm OD so that is effectively half inch. But the fittings for the 16mm tube only have an ID of 9.5mm, which is 3/8 inch.

So which measurement is everyone referring to? The internal diameter of the tubing, or the internal diameter of the 16mm tubing?


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Those are good questions. I was putting new water hoses in at the beginning of the season and was totally confused. The 1/2" hose could not use 1/2" fittings. You had to use 3/8" fitting to connect everything. Plus, different companies used slightly different sizes and called them 1/2"

I was just at the store buying some PEX tubing and fittings and was happy to see that the 1/2" fittings all fit the 1/2" tubing.

I just noticed that there are both copper crimp and stainless steel cinch rings available. I bought a clamping tool that works with the copper crimp rings but I don't think it works with the cinch ones.

Once assembled, I doubt if I'll want to disassemble it. I've never taken apart water systems in my house once installed. So, I think using these crimp rings would be fine. I tried a Sharkbite fitting in the store and noted they you can disassemble them relatively easily.

Other than ease of assembly, does anyone have a reason to use Sharkbite fittings?

[kmacdonald]

Originally Posted by Bigjim

Those are good questions. I was putting new water hoses in at the beginning of the season and was totally confused. The 1/2" hose could not use 1/2" fittings. You had to use 3/8" fitting to connect everything. Plus, different companies used slightly different sizes and called them 1/2"

I was just at the store buying some PEX tubing and fittings and was happy to see that the 1/2" fittings all fit the 1/2" tubing.

I just noticed that there are both copper crimp and stainless steel cinch rings available. I bought a clamping tool that works with the copper crimp rings but I don't think it works with the cinch ones.

Once assembled, I doubt if I'll want to disassemble it. I've never taken apart water systems in my house once installed. So, I think using these crimp rings would be fine. I tried a Sharkbite fitting in the store and noted they you can disassemble them relatively easily.

Other than ease of assembly, does anyone have a reason to use Sharkbite fittings?

The Sharkbite fittings are expensive. I like the copper crimp method the best and the tool is different for the SS cinch rings. The advantage of the cinch rings is that one tool works for all sizes but we don't have to worry about that because we only use 1/2" or 3/8". (some might use 3/4") Crimp tools are available to do both. There is a tool to cut the crimps off but you can just cut the hose. Use a PEX cutting tool to cut the hose for nice square cuts.

[pcmm]

Originally Posted by kmacdonald

The Sharkbite fittings are expensive. I like the copper crimp method the best and the tool is different for the SS cinch rings. The advantage of the cinch rings is that one tool works for all sizes but we don't have to worry about that because we only use 1/2" or 3/8". (some might use 3/4") Crimp tools are available to do both. There is a tool to cut the crimps off but you can just cut the hose. Use a PEX cutting tool to cut the hose for nice square cuts.

You don't even need "the correct tool" to work the SS rings. Just $10 pair of large "end nippers" from HF will work just fine for the pressures onboard!

[Cadence]

Originally Posted by BigBeakie

I'm a bit confused on this discussion of 3/8th & 1/2 inch PEX. I just went and bought some Sharkbite Pex tubing and fittings. Also got some SmartX fittings from Bunnings to compare.

They only have 16mm ( which they call 1/2 inch) tube & 20mm ( called 3/4) tube O.D. The I.D. of these is 12mm for the 16mm OD so that is effectively half inch. But the fittings for the 16mm tube only have an ID of 9.5mm, which is 3/8 inch.

So which measurement is everyone referring to? The internal diameter of the tubing, or the internal diameter of the 16mm tubing?


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Tubing is expressed in OD. pipe in ID. The OD/ID is ? depending on the type of tubing thus wall thickness. That's probably no help. I'd just go by what is conventionally used.

[P3sailor]

The only thing I would do is add some shut-off/isolation valves at a few key locations so the whole system wouldn't be disrupted in the event of a leak or faucet change. Best of luck on your project. Didn't realize PEX came in 3/8"!!

[kmacdonald]

Originally Posted by P3sailor

The only thing I would do is add some shut-off/isolation valves at a few key locations so the whole system wouldn't be disrupted in the event of a leak or faucet change. Best of luck on your project. Didn't realize PEX came in 3/8"!!

It isn't very common except in marine and RV applications.

[BigBeakie]

Originally Posted by kmacdonald

It isn't very common except in marine and RV applications.

Are you saying PEX tubing comes in 3/8" OD, i.e. 9.5mm? I don't think there is any of that in Oz.

[BigBeakie]

Originally Posted by Bigjim

Those are good questions. I was putting new water hoses in at the beginning of the season and was totally confused. The 1/2" hose could not use 1/2" fittings. You had to use 3/8" fitting to connect everything. Plus, different companies used slightly different sizes and called them 1/2"

I was just at the store buying some PEX tubing and fittings and was happy to see that the 1/2" fittings all fit the 1/2" tubing.

I just noticed that there are both copper crimp and stainless steel cinch rings available. I bought a clamping tool that works with the copper crimp rings but I don't think it works with the cinch ones.

Once assembled, I doubt if I'll want to disassemble it. I've never taken apart water systems in my house once installed. So, I think using these crimp rings would be fine. I tried a Sharkbite fitting in the store and noted they you can disassemble them relatively easily.

Other than ease of assembly, does anyone have a reason to use Sharkbite fittings?

Why Sharkbite? Well I bought a cheaper knock off SmartX from Bunnings to comparenand some of the quality differences are obvious, some are not, but they're there.

1. Sharkbite make the tubing and fittings. All of it in Australia. They have ISO QA standards. So what? The knockoff connector had a very loose interior lining that holds the steel grip clip. The retaining support for the lining tube was missing, so the grip on the PEX tubing was not nearly as strong, and it showed by how easily the ring can be depressed and the tube pulled out. The Sharkbite is harder to depress and the tube comes out but you need to apply force.
The shiny brass of the Chinese knockoff I would suspect has high lead content as opposed to the very low lead content of the Sharkbite.
2. The range of fittings available from the knockoff is much more limited. Sharkbite has manifolds, valves, shower bars fittings, etc etc.
3. The Sharkbite half inch/16mm connector at Reece Plumbing was $5.05 inc GST, while the knockoff in Bunnings was $4.50. A 50 cent saving for me was not enough inducement to buy lower quality.

I hate plumbing leaks that cause the demand pump to cycle endlessly, so anything I can do to prevent it, within reason, is good enough for me. And saving 50 cents per fitting is not worth the hassle down the road, IMO.

[kmacdonald]

Originally Posted by BigBeakie

Are you saying PEX tubing comes in 3/8" OD, i.e. 9.5mm? I don't think there is any of that in Oz.

It comes in 3/8" CTS.
Sharkbite makes it as do others.

[Biffer]

Originally Posted by Bigjim

I patched my water tanks and replaced a bunch of supply hoses last spring on the Columbia 10.7 I bought last December. I chose to base my system on 1/2" hoses.

I have a sink in the galley, a sink and a shower in the head. The boat originally had a hot water heater but it was removed.

My plan is to eventually replace the hot water heater, but for the moment I will live with cold water only.

The current hoses are Ok but air is getting into the system somewhere and I'm thinking I'd like to switch to PEX.

So, the question is: What is the preferred size for the system I'm envisioning, with hot and cold water, and three outlets?

1/2" or 3/4" tubing?

And, what size pump?

You will NEVER need more than 1/2”

[Biffer]

You will never need more than 1/2”