Replacing my grey PB tube water supply with 1/2" PEX

[TripleJ]

Im going to try to lay out what I did to replace all the grey polybutylene (or whatever its called, 'PB' from here on out...) plumbing with 1/2" PEX pipe.

My '85 was plumbed with the typical 3/8' OD grey semi-flexible tubing with the aluminum crimp rings securing the joints.  Last weekend filled the fresh water tank and turned on the pump for the first time.  I was met with at least one broken T fitting under the kitchen sink and several weeping fittings thruout the rv.  Not to mention the fact that most of the valves and drains were seized and I really couldnt even have drained the system if I wanted to.

I didnt take any before pics, but I can tell you that when you rip all the old stuff out it looks like this:


I will say that the reason I decided on 1/2" PEX rather than 3/8" was partly because the store that I was going to had very little in the way of 3/8" PEX fittings to choose from, and partly because the tool to crimp the fittings was $40.  Since I already own the tool to crimp the 1/2" fittings I figured I would come out AT LEAST the cost of the tool ahead... Not to mention the greater selection of fittings...

The routing and access to the lines is going to be fully individual, but Im willing to bet the fixtures are almost universal, so Ill just go through what fittings I used where.

The one I dont have a photo of (because Im too lazy to go out and lift the queen bed right now) is the connection at the pressure side of the water pump.  I wasnt certain what fittings I would be needing, so I left the PB fitting and line attached to the pump, and just used a push-lock shark bite typefitting to join the 3/8" PB line to the 1/2" PEX.  Simple and its not leaking

parts:
WATTS Quick-connect P-602 1/2" CTS x 3/8" CTS

From there the PEX line is routed toward the shower fixture. A 1/2" poly-T routs the line up to where it attaches to the back side of the fixture with a NIBCO PEX faucet fitting.

parts:
NIBCO PEX PX02248CR2 poly swivel elbow adapter



From there the water line goes to the toilet.  Here I installed a shutoff valve, then adapted it to a flare fitting which connected to the existing brass elbow that is threaded into the back of the toilet.  I dont have pics of this area.  When I try to pressurize the toilet it is leaking badly, and I cant tell if it WAS broken or if I broke it.  Im planning on pulling the toilet out to see if there is an obvious problem or what the deal is...

parts to connect the toilet:
NIBCO N50 1/2" PEX to 1/2" MIP (the shut off valve)
WATTS LFA-177 3/8" FL to 1/2" FIP (coupling)
WATTS A-164 3/8" FL (swivel coupling)

From the toilet to the bathroom sink.  The fixture again uses standard faucet fittings.  A T from the main line to the fixture, then a faucet fitting at the fixture.

The PB pipe in the wall at the top pic is the 'city water' supply, pressurized source.  I dont plan on using this right now so I left it out, to be maybe looked into at a later date.

parts:
Sioux Chief 637X20PK2 copper/poly PEX faucet connector 1/2" PEX to 1/2" FIP swivel




From the bathroom sink the line goes to a T where it branches to the water heater and the kitchen sink.



There were already some adapters on the kitchen sink lines, so I just got the one that would connect the PEX to the existing adapters. No leaks so far.

parts:
NIBCO PEX PX81270XR1 female thread adapter 1/2" x 1/2"





Now the water heater.  The factory piping was a mess of valves and elbows that were probably there to allow a certain isolation or bleed or drain procedure for the water heater.  For the time being Im simplifying it to an in-out setup.  I cant think of anything that would be mandatory about all those valves other than isolating the heater for service, so Ill deal with that later. I had to adapt the PEX to a flare in order to connect to the water heater tank, as you can see.

parts:
NIBCO PEX PX81190XR1 male thread adapter 1/2" PEX to 1/2" pipe
WATTS LFA-172 3/8 FL to 1/2" FIP elbow adapter
WATTS A-164 3/8" x 3/8" swivel flare adapter





The cold water supply goes into the water heater, the hot water side comes out.  From here you can just read this post in reverse to follow the hot water supply back through the system until it ends at the shower fixture.

During this process I purchased three 25 foot rolls of 1/2" PEX, and probably used about 60 feet of it.  Total cost so far WITHOUT any drain valves and with a toilet thats still not functioning is about $120.  Those brass fittings are probably $4-$6 each and they add up fast.  The pipe, T's, elbows, and rings are cheap.

Things I still need to address are:

the toilet
low point drains
fresh tank drain is still PB and is seized up tight
isolation valves where I deem them necessary
upgrade the faucets

[TripleJ]

Yes you may notice that I dont really have any isolating valves or low point drains.  Im usually pretty good at installing things like this but for such a huge store, the menards near me has a surprisingly lousy selection of PEX inline shut off valves, and an even LOUSIER selection of employees.  No one in the plumbing section had any clue what I was doing or what types of fittings were in the store, and the fittings aisle was a disaster. That must be why everything is so cheap. minimum wage...

There was quite a bit of water splashed around in the process so Im running a dehumidifier on 'Atacama Desert' setting to pull some moisture out of the woodwork. (google it, I did. hah!)  I also found a broken drain trap under the kitchen sink, no doubt from having frozen.  I did get some remnants of RV antifreeze while first running the water so hopefully Im good when it comes to freeze damage



A few of the tools required



That crimp ring tool takes a whole lot of @$$ to use, especially in tight areas.  Bring your A-game or a pro arm wrestler if youre planning on using one.  They make another style, a cinch-crimp that looks much easier and is suppose to be reliable, tho the cinch bands dont look quite as pretty as the copper crimp rings in my opinion...  Like i said, I already own this one so I worked around it.  If I was starting from scratch I think Id go for the cinch tool.  I would STILL choose 1/2" PEX rather than 3/8" tho. That wouldnt change.

[sasktrini]

great post! 

[circleD]

I've thought about doing this same project. I replaced the kitchen sink and the gray fittings were leaking and dried out. I spent $30 for adaptor to a cut off valve to other lines. I have cut off valves now but one heck of a rigged plumbing job. You did it right and upgraded the whole thing. What about a master shut off valve inside so you don't have to turn it off outside?

[TripleJ]

Well I think I've got the torlet taken care of. I removed it from its base enough to see that I had it cross threaded into the threaded plastic inlet. I pulled the fitting, cleaned it and put some liquid teflon on the threads. All back together and seems the leak is gone

CircleD when I hook the city water inlet back up I'll probably add a shut off valve.

What I want the most is the low point drains. Now anytime I cut into the lines I'll have to deal with all the water in the system dumping out.

I really should have replaced the faucets before doing this, now I'll likely have to re-do the adapters for new fixtures when I get them... O well

[circleD]

I've used compressed air to push the water to the kitchen faucet. I use an air nozzle with electric tape wrapped around it to make a seal. I push 30-40 psi through the city inlet and have the kitchen fauct or any way for water to escape the lines open. It gets the bulk of it out and doesn't hurt anything.