1/2" or 3/4" PEX?

[guyrj33]

there are support brackets for 90 degree bends.

[phorvati]

3/4" is an overkill. I just did my suction lines(from tanks to manifold and then to Pressure pump) with 3/8" pex. I was worried that I might not have enough volume. But i have plenty. All three faucets are running petty good. I have not used the deck washdown yet to see if I regret the size.


I started the project thinking i'll use 1/2" pex. But cost for fittings was too high in my opinion. for 3/8" pex, its not as bad. You can get lucky on ebay and get packs of elbows and NPT to push-to-connect and pex much cheaper.

Careful that you really only get food grade or potable water grade fittings....

[Bigjim]

Originally Posted by P3sailor

1/2" would be much easier to work with, I would think that with the small number of "taps", 1/2" would more than suffice. Keep it simple.

I am a strong advocate of keeping things simple. The old system had multiple Ts and junctions and even splices. PLUS, the pickup hoses from the water tanks had no Y valve. It was designed to allow air into the system when one of the tanks went dry.

I'd like to minimize the length of the runs and the number of junctions and other fixtures and eliminate 90 degree fittings whenever possible.

[SkipperJer]

I did our boat in 1/2". I did it in the expansion system, ProPEX is one name for it. I do believe the other systems have metal in the rings (crimp) , shark bite has metal teeth. I was concerned that the metal would corrode in the salt water environment. The downside of the expansion system is the costly tool, about $400. Maybe that can be rented from the supplier. I found mine on Ebay.

[wrwakefield]

If you don't want to waste water getting hot to the shower and taps, run 3/8" ID PEX to your fixtures from either a manifold or 1/2" main line from pump.

Unless the vessel has long plumbing runs, 3/8" will deliver plenty of flow for your needs. [This is what we did on our 43' boat that has 2 heads w/ showers, galley, clothes washing machine, 2 deck washdowns with 3 way valves selecting from raw or fresh water. All have plenty of pressure and flow because they are all home runs from a common manifold. [Not Teed off of a long 3/8" run...]

Also, you might want to consider insulating the hot water lines. It will pay off...

Best wishes with your project.

Cheers! Bill

[Mikado]

Before I rebuilt my fresh water system with a Manabloc Manifold and Pex I experimented with sizes and the shortest and longest runs and found that 3/8” provided the best combination of pressure and flow.

[wsmurdoch]

Smaller means less wait for the hot water to get to the fixture and less wasted water while you wait.

Bill

[bcboomer]

I used 1/2" PEX but, if I did it again, I'd use 3/8". Easier to run, less heat loss etc.
I used the Watts packaged fittings but they are all marked "SeaTech".
Simple to use, even in hard to reach spots, and no expensive tool required.

[jen1722terry]

Question: do they make clear of translucent PEX? I have to replace a lot of old hose in our fresh water system for our 31 Cape Dory. I assumed I'd use the clearish plastic with the reinforcing fibers in it. Hadn't thought about PEX. I presume I would have to replace a lot of fittings for the PEX.

I just like seeing the antifreeze in all the hoses when I winterize. Probably not necessary but I like it.

Cheers!

Terry

[bcboomer]

I've only seen red, white and blue. The red and blue are translucent enough to see a water level when backlit.

[Cadence]

I'd use 1/2". JMHO

[Hunky Dory]

Do not worry about 1/2" being large enough for you boat. A lot of homes have 1/2" water piping and 3/8" flex going to the toilets and taps. If you look inside a tap you will find a small hole in the seat probably no more than 3/8" With a boat, you normally would not use more than two faucet outlets at a time X 1.3 gal per minute each, your pump will be the governing factor. As someone already said 3/8" would work just fine. As for fittings the pressure drop per fitting is minimal and with PEX you can eliminate some of them just by warming up and bending the pipe. A suggestion is to use Shark Bite or GatorBite push on fittings, great if you want to take your system apart for any reason, I have never had any of these fittings leak, you do not have to crimp so they work great in confined spaces .Dont worry be Happy

[Bigjim]

Here is a diagram of my plan


(Click to enlarge thumbnail)

Does anyone see any issues or problems?

[Bigjim]

Originally Posted by jen1722terry

Question: do they make clear of translucent PEX? I have to replace a lot of old hose in our fresh water system for our 31 Cape Dory. I assumed I'd use the clearish plastic with the reinforcing fibers in it. Hadn't thought about PEX. I presume I would have to replace a lot of fittings for the PEX.

I just like seeing the antifreeze in all the hoses when I winterize. Probably not necessary but I like it.

Cheers!

Terry

From everything I've read, you would drain hot water lines (and heater) and winterize cold water.

[Mikado]

Originally Posted by Bigjim

Here is a diagram of my plan


(Click to enlarge thumbnail)

Does anyone see any issues or problems?

As long as you plan on investing in a manifold and running home runs instead of daisy chaining the cold, I would do the same for the hot.