[lesp]

I am tearing out the corroded galvanized pipe in my house bit by bit. Here is my plan for redoing the kitchen and laundry area. Have I sized the PEX correctly? (FYI: the kitchen/laundry is 10'x14' and it is 7' from where the water supply enters the house.) Also, do I have all the right fittings for transitioning to the fixtures? I'll be using Uponor/Wirsbo -- any tips to ensure I get it right the first time?

Thanks in advance!

 

[VIPlumber]

Looks good to me.

 

[lesp]

Thanks VIPlumber! I have never done this work before -- just read a lot of installation guides. Any tips for making the install go smoothly?

 

[ScottR]

Remember that PEX can expand and contract a LOT, especially as compared to copper or steel.

http://www.engineeringtoolbox.com/thermal-expansion-pipes-d_283.html

You can use the formula on that page to figure out roughly how much your runs will expand/contract -- remember on a hot day the cold side may contract quite a bit, and the hot side will expand a lot on a cold day so you have to leave "wiggle room" for both. Most installation instructions recommend making an "S" shape at either end of the run.

The linear expansion coefficient can be found in the mfr. datasheets. E.g. Wirsbro AQUAPEX has a linear expansion coefficient of 9.2*10^-5 in/in-degF, and so a 10 ft. length of AQUAPEX will expand by ~1.38in. when heated from 55F to 180F. Doesn't sound like a lot, and your installation isn't very large, but it could put stress on your fittings if you don't account for it.

(Incidentally, steel pipe would expand ~0.1in. under the same conditions).

The first time I did a PEX install I didn't take the expansion into account and that caused me some headaches, especially since it was all on the HW supply side.. hope to save you the same.

EDIT: I'm no professional, but your layout looks right-on to me too. (And if you wanted to go nuts, you could home-run each appliance/sink group back to a single point so you can shut off one without shutting off all. I did that with my PEX refit, but it was more just for fun than any compelling reason :laughing: ).

 

[Homerepairguy]

Lesp,

My philosophy of a trunk & branch PEX system is:

1. Never have connections in the attic. (Like the T connection on your blue cold water line.) A leak can cause catastrophic damage.
2. Never have intermediate connections in double walls where I can't get to them. (Like the T connection on your blue cold water line.)
3. The source manifold has all 3/4" outputs and has an access panel at a comfortable working height while standing on the floor.
4. Remote manifolds at the fixture ends convert the 3/4" trunk lines to smaller lines to feed fixtures "in the immediate vicinity". These manifolds can be in double walls but with access panels if at all possible. If an access panel is not feasible, then an easy way to open the wall later without too much damage.

For example: (One trunk line for hot and one trunk line for cold.)
- One 3/4" trunk line to the dishwasher and double sink area with a remote manifold right there to feed each fixture there.
- A different 3/4" trunk line to the laundry room with a remote manifold right there to feed the washing machine and laundry tray.
- A different 3/4" trunk line to the bathroom with a remote manifold to feed the vanity and bathtub/shower.

The biggest rule I have is to have connections ONLY at the source manifold and remote manifolds. NEVER any connections in between. Just my own philosophy and not saying your diagram is not doable.

EDIT: PEX tubing length expansion and contraction is rated at: 1 inch per 100 feet per 10 degrees Fahrenheit change. Large effect on hot water lines. Not so much on cold water lines.

HRG

PS: I remember reading that some city codes require that connections at both ends be accessible. Maybe verify the codes in your area.

 

[VIPlumber]

ScottR,


Ain't no way they're going to run 180F water, more likely 120-130F.

PS - Hicksville is a nice little place. I was in a soccer tourney there back in the early '80's.

lesp,

I don't have a lot of experience with the Wirsbo system, but I'd strongly suggest you make a few practice fittings first. It's a pain if you don't get the ring & tube properly expanded to go over the fitting, or if you don't get it on in time.

HRG is bang on with his observations, esp the part about the less fittings (if possible) the better. Less fittings = less flow restrictions. Takes a little planning, but I'm sure you're up to the task.

 

[TheEplumber]

Looks good but for one thing. You show a straight stop behind the dishwasher. I'd put it under the sink and run a 3/8 flex line to the DW. This way you have access to the valve without having to pull the appliance

 

[lesp]

Thanks for all the input -- it's all very helpful. Here's the newest plan with the dishwasher teeing off the sink line.

I did think about using the remote manifolds, but because I have so few fixtures, it didn't seem to make sense. I would have to run a lot more pipe and I'm not looking forward to making more holes in the joists. Also, the connections will be in the joist bays over the basement, so I will be able to keep an eye on them.

I will definitely practice making the connections. I understand you have to be fast getting the fitting on the pipe. Any other tips for actually managing the giant coil and getting it in place?

Thanks again -- this place is awesome! :thumbsup:

 

[ScottR]

Ain't no way they're going to run 180F water, more likely 120-130F.

PS - Hicksville is a nice little place. I was in a soccer tourney there back in the early '80's.

OK, maybe I was a little overboard with the 180F figure. :laughing: I guess 140 would have been more reasonable as a worst-case (I crank my HWH up all the way an hour before using our soaking tub). And I might have been a little high on the 55F if any of the PEX is going into unconditioned space. My point still stands; if you're used to running copper and switch to PEX, the expansion can catch you by surprise.

Finally, someone who's heard of Hicksville! Usually people have to ask if it's a real place, or if I just live in the sticks. :thumbup:

 

[Homerepairguy]

I did think about using the remote manifolds, but because I have so few fixtures, it didn't seem to make sense. I would have to run a lot more pipe and I'm not looking forward to making more holes in the joists. Also, the connections will be in the joist bays over the basement, so I will be able to keep an eye on them.

Running 3/4" trunk lines to each location, like kitchen, bathroom, and laundry also reduces drop in water pressure like if you're running the dishwasher and washing clothes at the same time. The dishwasher may not get the volume of water it needs to do a good cleaning job. But if your other half and you are willing to regulate usage, then no problem.

Since your bathrooms are not on the trunk lines you showed, then at least you won't experience the too hot or too cold showers when the dishwasher or washing machines use water.

It's not necessary to use remote manifolds at the fixture ends when running individual 3/4" trunk lines to each location. Just connect the fixtures like you plan to do now.

But I know what you mean by using less PEX tubing and having less work though. I ran one hot and one cold trunk lines to our back to back bathrooms and my wife doesn't fill the bathtub in the master bathroom while I'm taking a shower in the second bathroom.

All the best with your plumbing project,
HRG