pipes are made of plastic ?

[pawntan]

I notice all RV internal pipes are always made of plastic including the heads/screws.
Is there a reason why they are all plastic , not brass/ stainless steel screws ?

My winterizer kit has stainless steel head screw.
If I install that metal head screw against a plastic pump thread, would that be OK ?
I wonder if there is a concern that different material expand/contract at different rate at heat/cold, and thus the plastic will break ?
Is that a reason why all RV pipes are made of plastic ?

[motorbreath]

I think there are two reasons:

1) Plastic is cheaper.
2) The PEX (plastic) piping is more tolerant to freezing.

I have done some work on my piping and used brass fittings with PEX, but I think the plastic fittings are fine. One thing I am concerned with are the plastic shutoff valves, I will replace those with brass ball valves eventually.

Originally Posted by pawntan

I notice all RV internal pipes are always made of plastic including the heads/screws.
Is there a reason why they are all plastic , not brass/ stainless steel screws ?

My winterizer kit has stainless steel head screw.
If I install that metal head screw against a plastic pump thread, would that be OK ?
I wonder if there is a concern that different material expand/contract at different rate at heat/cold, and thus the plastic will break ?
Is that a reason why all RV pipes are made of plastic ?

[jenoble99]

The reason boils down to ease of installation and more than anything cost of materials and labor to install.

[RVhiker]

I like copper pipes in my house and PEX in my trailer. Pex is easy to install, lightweight and somewhat flexible. If you've ever looked at how piping is installed in trailers, being flexible is important as you go bouncing down the road.

[BigJohnD]

I always have shared my harsh thoughts with manf. about using junk plastic fittings (90's, T's etc) with pex tubing. What good is having pex tubing if your fittings are junk. The pex won't break / crack easy with a freeze, but you can guarantee the small plastic fittings will. Any time I redo something with the pex in any RV, it doesn't go back together with a plastic fitting.

[Grumpy]

Originally Posted by BigJohnD

I always have shared my harsh thoughts with manf. about using junk plastic fittings (90's, T's etc) with pex tubing.

Those plastic fittings are also made by Nibco who make the PEX system

http://www.nibco.com/PEX/PEX-Fittings

[Brownie]

[QUOTE=motorbreath;376275]I think there are two reasons:

1) Plastic is cheaper.
2) The PEX (plastic) piping is more tolerant to freezing.
QUOTE]

Two more reasons PEX is used:

3) PEX is a lot lighter in weight;
4) PEX is a lot more flexible. Copper works great in your home, but you don't pull your house down the road at 65 (+) m.p.h.! Soldered joints would surely crack & break from all the vibrations, etc.

The crimped-on fittings (connections) certainly are the weak points of the system. But band-crimping is fast and (once you pay $60+ for the crimping tool) inexpensive. That's why they're used in the assembly line manufacturing process. I use to do quite a bit of plumbing work in mobile homes, which also use PEX tubing. Whenever I have to replace a valve or fitting, I always use a "Shark-bite" fitting. They have brass bodies, are even faster to install than PEX fittings, are considerably ore reliable, and you can remove & reinstall them easily if needed. They are a bit more expensive, but worth the $ IMHO.

[Tunce the traveler]

[QUOTE=Brownie;376365]

Originally Posted by motorbreath

I think there are two reasons:

Whenever I have to replace a valve or fitting, I always use a "Shark-bite" fitting. They have brass bodies, are even faster to install than PEX fittings, are considerably ore reliable, and you can remove & reinstall them easily if needed. They are a bit more expensive, but worth the $ IMHO.

X2

[Hohenwald48]

I love PEX tubing but always use metal fittings and crimp rings (no clamps). I've had and heard of folks having a lot of trouble with the plastic fittings. Why take the chance? Metal fittings are cheap. I can't do anything about what the manufacturer did but any mods or repairs are done with metal fittings.

[dalebra]

PEX is the 21st Century normal. All new homes in my area are all plumbed with PEX.

[Camping Couple]

If you want brass fittings without the metal clamps, Home Depot carries "shark bite" fittings that work with PEX tubing. Push the tubing into the fitting and it locks in place. I had to replace a bypass valve in the fall for the water heater. Worked great!

Shark bite fitting $2.29
Plastic replacement valve $.89

I'll stick to the shark bite valve for piece of mind.

[BigJohnD]

I realize the plastic fittings are made by Nibco, but that is still the weak point regardless. The 90's will crack or break long before the tubing. The tubing I know will expand quite a bit.

[pawntan]

When installing the winterizing kit, due to tight corner I have to connect using hose that has metal screw head (from home depot) into the black plastic intake of the pump.
See the picture attached.
Would it be a problem to thread in a metal screw head to a pump thread that is made of plastic.
Would it cause problem during freezing temperature since metal and plastic expand and contract at different rate ?

[pawntan]

more picture zoomed in

[Grumpy]

Won't be any issues. Many of the kitchen faucets are metalic connected to the plastic pipe.

[Hohenwald48]

Originally Posted by Camping Couple

If you want brass fittings without the metal clamps, Home Depot carries "shark bite" fittings that work with PEX tubing. Push the tubing into the fitting and it locks in place. I had to replace a bypass valve in the fall for the water heater. Worked great!

Shark bite fitting $2.29
Plastic replacement valve $.89

I'll stick to the shark bite valve for piece of mind.

Sharkbites work well provided you are careful to get the tubing fully seated in the fitting. A lot of folks stop at the first "click" and end up blowing the tubing out of the fitting. Additionally, some Sharkbites can get pretty costly. Sharkbite is a brand name and there are many others that work on the same principle. They do have a neoprene "O" ring seal on the inside that can be damaged during installation. I don't know if the "O" rings can deteriorate over time.

I don't think anything beats a good crimp ring on a metal fitting if you have the proper tools.