PEX replumbing diagram sanity check

[Al-lacrimae]

I'd appreciate any advice the friendly folks here can give about PEX system design and installation. I've done some skimming through the forums on it and learned a lot, so here's my initial design.


I'm already considering adding an accumulator after the pump and a basic sediment filter before it, and I have read to be very careful with the freshwater tank connection. I'm also planning on rubber mounting the pump and using hose before and after to cut down on the noise.


Fittings will be Flair-It PEXLOCKs for all the PEX-to-PEX, sharkbites for the PEX-to-copper (old shower & bathroom sink are staying until the remodel), and the freshwater, kitchen sink, and city water connections are TBD.



What else am I missing?

[Bubba L]

We used ProPEX in both our trailers. I added inline valves to every fixture in the event something froze or leaked. Good luck

[57Vintage]

If you have a tankless water heater you might want to consider a return line to reroute water from the farthest hot water lead back and allow it to return to the heater or even to a FW tank. I control this with a shut off valve in the kitchen.

Return line

to shutoff valve

(valve has long shaft to allow handle to be above counter

to diverter valve

TO H2O heater or FW Tank

Because my layout forced me to place the water heater just forward of the kitchen, my rear bath can use a lot of water to get hot water. (Need to watch usage if no city water plus the additional water in GW/BW tank.) I put a diverter valve on this return line to route to the water heater or to my forward fresh water tank. Trying to get the most out of the extra effort so I can also fill my FW tanks while being hooked up to city water.

Probably not of benefit with a tank heater.

[GCinSC2]

Al

I’d be curious to hear your hands on feedback on using the PEXLOCK clamps. I bought a supply for PEX plumbing on the AS. Just haven’t used any yet.

Gary

[A W Warn]

Originally Posted by Al-lacrimae

I'd appreciate any advice the friendly folks here can give about PEX system design and installation. I've done some skimming through the forums on it and learned a lot, so here's my initial design.


I'm already considering adding an accumulator after the pump and a basic sediment filter before it, and I have read to be very careful with the freshwater tank connection. I'm also planning on rubber mounting the pump and using hose before and after to cut down on the noise.


Fittings will be Flair-It PEXLOCKs for all the PEX-to-PEX, sharkbites for the PEX-to-copper (old shower & bathroom sink are staying until the remodel), and the freshwater, kitchen sink, and city water connections are TBD.



What else am I missing?

You might consider:
-pressure reducing valve (regulator) if the shore water inlet does not include one
-depending on the type of shore water inlet, you might need a check valve to stop flow outward at the shore water inlet while using the pump.
-on your diagram there are 6 pipes going to the 4 port manifold
-if a manifold malfunctions while camping you can't repair it on the spot unless you carry a spare manifold. Would it be better to use a series of tees, since carrying a few spare plumbing fittings is easier and a lot less expensive?
- if you use antifreeze for winterizing, add a valve behind the sediment filter into pump suction pipe so that you can use the pump to install the antifreeze.

[bibbs]

I think 1” feed pipe is overkill, 1/2” should be plenty for a trailer.

[gr.austin]

Pex is great if installed properly. The major benefit is that you can run it with only 2 fittings. One at the source and one at the end. No hidden fittings to break or leak. By hiding fittings defeats PEX. !/2" will supply up to 10gpm 5x what you would normally use. As for the pressure regulator that is up to you. With PEX and no fittings the Pipe can stand up to 150 PSI 3x what would normally be available. Even under the worse of conditions your new piping would handle the pressure with no problem. Good luck remember no buried fittings.

[mshumer995]

One question about the hot water return line. Do you have a pump to move the water? Otherwise, how are you going to get the water to move through the return line?


I've considered a similar setup on my house but it requires a pump in the bypass line to get water moving.



Cheers

[strangepod]

+1 for the pressure reducing valve, either internal or external. Yes pex can withstand higher pressures but lets not forget about your fixtures and water heater. Given enough pressure(incoming) your pressure / temperature valve on your water heater can 'blow off' (leak water to prevent the water heater from going BOOM!)


Also I would put shut-off's at each faucet so if you need to service them etc.(and use ball valves, sooo much nicer).


My 3 cents...


John

[jayness2020]

Speaking of pressure regulators -- what would be the ideal pressure in the system? I'm redoing all the plumbing in our 1972 Overlander, using PEX.


Also, can you use a "portable" regulator at the water source, between the spigot and the hose going to the trailer?

[BigTexRex]

If you use PEXPro fittings, make sure you use PEX A tubing and not PEX B. https://youtu.be/XRNKDrGlOls

[Wazbro]

Originally Posted by jayness2020

Speaking of pressure regulators -- what would be the ideal pressure in the system? I'm redoing all the plumbing in our 1972 Overlander, using PEX.


Also, can you use a "portable" regulator at the water source, between the spigot and the hose going to the trailer?

I believe the standard for RV city water inlet pressure regulators is 45 PSI. You should definitely keep it under 60 PSI. (Some campgrounds have over 100 PSI in their system to supply enough volume.)
Yes, absolutely you can use a regulator at the source. When the campground has excessive pressure it will also protect your hose. (You should always use a water filter before regulator to keep dirt out it.)

[Trons4u]

We're restoring our trailer, I just finished putting in all new 1/2" and pressure tested up to limited to 55psi with an external pressure regulator. We also just last week had a Truma water heat put in. With either the city water connection or the pump there was plenty of pressure at all outlets. I wouldn't use a manifold either, all of my connections are either tee's, elbow's or ball valves. I would recommend isolating places where you can. I put a valve on the outlet side of the pump so I can close it when on city, I also put a valve on the city water inlet so I can close when using the pump. I also added isolation valves after the water heater going to the head. All outlets (sinks, tub) have their own individual shutoffs also.

Tony

[Al-lacrimae]

@57Vintage Unfortunately I'm not at the stage where I'm getting a tankless, though that's definitely one the someday wishlist for the full monty remodel. Shutoff valves, specifically ball types, at the outlet ends for the sink sound like a great idea as that's my long run.


@GCinSC2 I'll try to post some updates when as I do it/when I finish. I've got the rest of my work at https://www.airforums.com/forums/f44...in-208432.html I should really update my signature now that I'm doing some work on the computer, everything else has been from my phone.


@A W Warn Thank you for the list of suggestions!
-pressure reducing valve (regulator) if the shore water inlet does not include one
I have one on the city water in line downstream of my filter.

-depending on the type of shore water inlet, you might need a check valve to stop flow outward at the shore water inlet while using the pump.
That's on the diagram just prior to the T

-on your diagram there are 6 pipes going to the 4 port manifold
The inlet and outlet are not considered ports for this miniblock https://www.pexuniverse.com/49043-vi...alloy-manifold

-if a manifold malfunctions while camping you can't repair it on the spot unless you carry a spare manifold. Would it be better to use a series of tees, since carrying a few spare plumbing fittings is easier and a lot less expensive?
I was trying to save a bit of space and reduce the number of connections, but you are right, it is a single point of failure for the freshwater system. Something I'll have to think about some more.

- if you use antifreeze for winterizing, add a valve behind the sediment filter into pump suction pipe so that you can use the pump to install the antifreeze.

THAT'S the kind of specific thing I'm looking for and hadn't even thought of. Not much experience with winterizing here is S GA, but future moves could take me darn near anywhere, so I'll need the ability.


@bibbs Any technical reason its a bad idea? The manifold inlet is geared for 1" so I'll have to use a reducing fitting, so I figured I'd differentiate the supply with white 1" and be able to take it straight into the manifold.


@gr.austin Exactly! No buried fittings! Everything labeled and color coded so its easier to fix when something breaks... even though hopefully it won't.


@strangepod The runs from the manifold to the bathroom are very short, so I'm planning to reduce the number of fitting by not including cut offs at those ends, but the kitchen sink long run will have them.


@Wazbro Thank you, the filter prior to the pressure regulator totally makes sense now.


@Trons4u The intent of the manifold is to isolate each section at the source and cut down on the total number of fittings, reducing the footprint while doing so. I have a check valve prior to and a ball valve off the hot water heater, so I think I meet the intent of what you were saying?


Folks, thank you SO MUCH for your helpful comments. I'll try to remember to post result here in addition to my main thread https://www.airforums.com/forums/f44...in-208432.html, but still open for advice as I'm not starting the install until this weekend 6 June. Version 2 of the diagram with advice and an accumulator upgrade included. If nothing else, wish me luck and the fewest number of busted knuckles as I can manage!

[A W Warn]

If you use a winterizing/antifreeze valve it needs to be the first item in the pipe coming from the water tank. If it's installed in this position it will put antifreeze into everything that needs protecting, especially the strainer and pump head. A few drops of liquid are left in them after draining.

Also, if you use the winterizing valve you will need valves on both sides of the water heater, so that antifreeze does not fill the HW tank. Therefore, you also need a bypass pipe between the hot and cold, with a valve that is normally closed but open during winterizing, so that the hot water pipes will be filled with antifreeze when the two valves at the water heater are closed during winterization.

If you are going to use air, blowing through the pipes for winterizing, you can do that through the shore water inlet, using a screwed on fitting. But that does not take care of the strainer and pump head, which has to be taken loose in this case. The pump instructions say to disconnect the pipes and run the pump to winterize. This step can be skipped if antifreeze goes through.

[bibbs]

The 1” pipe and manifold will work just fine, I just think the larger pipe is less flexible and fittings more expensive, and harder to work with. On the trailers I have done I just ran the cold water line, to the kitchen, with T's going in or out as needed, for everything else.

[SailorSam205]

Originally Posted by A W Warn

If you use a winterizing/antifreeze valve it needs to be the first item in the pipe coming from the water tank. If it's installed in this position it will put antifreeze into everything that needs protecting, especially the strainer and pump head. A few drops of liquid are left in them after draining.

Also, if you use the winterizing valve you will need valves on both sides of the water heater, so that antifreeze does not fill the HW tank. Therefore, you also need a bypass pipe between the hot and cold, with a valve that is normally closed but open during winterizing, so that the hot water pipes will be filled with antifreeze when the two valves at the water heater are closed during winterization.


Also, before putting in the accumulator, check the specs for the pump you are using. I've read that some pumps recommend against using an accumulator.


If you are going to use air, blowing through the pipes for winterizing, you can do that through the shore water inlet, using a screwed on fitting. But that does not take care of the strainer and pump head, which has to be taken loose in this case. The pump instructions say to disconnect the pipes and run the pump to winterize. This step can be skipped if antifreeze goes through.

X2 on both the location of the winterizing port and water heater plumbing. There are several ways to do the WH with varying numbers of valves. If using on/off valves, you need 3 and 2 tees. There are valves that can reduce the number (they redirect the flow between multiple outlets).

[Al-lacrimae]

Ah, the familiar “what we’re they thinking?” directed at a PO. Obviously a lot of work has gone into this trailer over its 41 years of life... but there’s always room for improvement. Who puts a freshwater inlet directly next to the black water dump outlet... seriously, 3” away!

So I’ve dismantled the previous plumbing setup all the way back to the freshwater city inlet line from the reel (not the additional one next to the poop tube). I’m not touching the fresh tank yet as we’re not ready for boondocking and this is a staged remodel as we use this Cozy Can regularly.

There’s a nice picture of all the different sorts of plumbing found. Copper of multiple sizes, various reducers and couplers for a myriad of tubing types and sizes, and a few items I think were original equipment like the pressure relief valve.

Big positive found, the hot water has a nicely done bypass setup with valves and threads in good shape that I’m keeping. Yay!

I’m got v3 of the diagram done in the computer that I’ll post later, but based on the tear down and running the new PEX lines to the kitchen sink I’m altering one big thing. My mini-manifold will be accessible from the back bumper hatch. I was originally going to cram it into the same under-cabinet area as the hot water heater and decided that’s just too uncomfortable to work in! So the hot water area will be the hot water area, with a T off the bypass to go forward and aft, and 2x T’s in back for the drain, bathroom sink, and shower. The freshwater manifold will have the line in per the diagram... but I have decided to use the existing braided hose for input as it’s in good shape and already all connected to the reel. When I go back to hook up the freshwater tank I’ll likely replace it with 1/2” white PEX, I looked up the flow rate of 1/2” and as has been pointed out here’s nothing gained by a larger size then the extra cost for fittings. So, all 1/2” fittings means it’s also easier to fix anything by keeping one size of fitting on hand. KISS principle!

[Al-lacrimae]

Here's V3, installation work starts today! Also added a hose connection at the bottom of the mini-manifold as the drain, it's located in the back bumper area and can also thus be used as a rinse hose for the stinky slinky, outdoor cold shower at the beach, etc...


Any recommendations for the type of pipe support/clamp I should use for the 1/2" PEX?


I was thinking of these, they look like they'd provide both support and allow some road wiggle. The current bands have just one screw into the inner wall and are looking worn, especially at the edge that would cut into the PEX.


@Bibbs - Thank you for sanity checking me on the 1" pipe, hopefully you caught that I switched to using 1/2" for everything and can thus keep one type of "spare" for fittings.

[Al-lacrimae]

So after a couple mid-steps I got the city water side of the diagram installed.

Things I’ve learned:
-PEX Press is a proprietary Viega connection that no one else uses, takes a special tool that no one rents, and is NOT the same as a push to connect fitting. I bought the manabloc with these type of fittings based on an assumption and incomplete research... and I paid for it by getting a nice jet of water in the face and the time and couple $ it took to replace them with a crimp type fitting.
-I should have purchased much less PEX tubing, and just bought it locally. 50’ of blue, and probably 30’ of red would have covered it with slop.
-Never assume the hose size matches, measure. My project got somewhat delayed by a 5/8” female to hose barb fitting that could not be purchased locally. The POs has used 1/2” hose everywhere else so based on appearance I thought it was the same... I learned.

So my main thread has the details on finding a section of bad floor mid-replumb and getting totally derailed by that... but I finally got everything put back together. All the correct size fittings, all the working connectors, and just need to go through another round of pressure/leak tests before I’m satisfied it’s “done” for this phase. I’ll be putting in white 1/2” PEX for the input line when I go back for round 2, but the city water side is functional!

I’m planning on some foam covers for all the lines to prevent UV exposure once I finish the leak check but pictures are going to be less intuitive/interesting once everything is covered.
Pictures below are:
-Hot water heater before I finished re-assembling the cabinet (which got taken apart for the floor issue, not re-plumbing) and missing input line.

-Shark bite connection to existing shower and bathroom sink lines based on accessibility and phased remodel plans. The “sub-out” for an outdoor shower connection is also visible.

-The mini-manabloc setup, one line right for bathroom fixtures, three left for toilet, kitchen and hot water input. Hot water output to bathroom tucked in there.