Replumbing the house, just ordered a MANABLOC manifold

[Rectifier]

I think these are really cool if you have never seen them.

http://www.amazon.ca/gp/product/B008J33N5E/

I've seen these a couple times while on the job and am always impressed for a couple reasons:
- built-in shutoffs for all fixture lines in one location
- 100% HDPE, practically inert and immune to any attack by bad water
- looks really nice and clean
- zero fittings in the walls
- independent lines to each fixture means no pressure drop, at least until the well pump's capacity is reached
- shorter runs of smaller pipe get the hot water there faster

So since I really don't like the plumbing of my house as it includes such things as hose clamps holding together copper lines,and completely baffling routing of pipe up and over the living room for no reason. Since the appropriate drywall is off anyways, I decided to bite the bullet and redo the whole house in PEX and do the job right.

A manifold system is perfect for me since my mechanical room is right in the center of the house, with the kitchen above it, one bathroom above that, and the other bathroom 20' away on the main floor. So everything will be centralized short pipes. And I can get the shower working for the wife while still running other pipe, thanks to the shutoffs!

Pretty excited about this thing. I feel it would have cost me as much just to buy all the tees and shutoff valves, plus hours of crimping it together and trying to mount it on a piece of plywood.

In classic Canadian pricing, they are $500 at the supplier and $120+shipping in the USA. And that would be with my "privileged" tradesman's pricing even, plus a several week wait to order it in.
Surprisingly Amazon was the best deal in Canada, $200 well spent with free 2-day shipping. I'm hoping to bring the whole plumbing rework in for ~$500 including buying my own pex tools. Spend more on the manifold, save on fittings, pipe is cheap.

[NorthwoodsMike]

I think you will be happy with pex. Be sure to insulate your pipes/hot AND cold before closing up the walls. Hot for obvious reasons. Cold because they can sweat should humidity rise.

I opted for these-as they have a crimp connection, which I prefer over compression fittings. They mount easily to plywood as well. The drawback is corrosion resistance, as you stated.
http://www.menards.com/main/heating-...724-c-8520.htm

If you can, try to get plastic crimp fittings. I used both in my project, and plastic was so much cheaper. One drawback is they are a one time use. With metal, the ring can be cut off, and the fitting re-used, but that is a rare occurrence.

Another piece of advise, try to get pex water heater connections, along with pex hose bibs-it's much better than using threaded adapters.

[Rectifier]

I am going all plastic fittings too, nothing to corrode. If kept out of the sun HDPE will last a century (or more, not enough data yet)
The manabloc is available in crimp in the USA. That's what I wanted but compression is all that I could get here... Have to be very careful with pipe strain.

In our climate humidity is not an issue - you could dump a gallon of water on the floor and it would be gone by the end of the day

[wharton]

Originally Posted by NorthwoodsMike

I think you will be happy with pex. Be sure to insulate your pipes/hot AND cold before closing up the walls. Hot for obvious reasons. Cold because they can sweat should humidity rise.

.

Pipes sweating in the walls is a common misconception. Sweating occurs when the pipe is exposed to moist air. All penetrations into the wall cavity, drilled holes in plates, places where pipe exits drywall etc... should be caulked and/or fire sealed. If done correctly, there is no moist air in the cavity, and no sweating.

As for manifolds and all the massive amount of redundant piping, and cost they create, I'll pass. As a small custom home builder, I spent years doing all my own plumbing. I use a trunk line set up with PEX. 3/4" main lines to 1/2" lines to individual fixtures. Several things made it quite clear that there is little, to no, benefit with the whole manifold system.

First, the big selling point is "you never have a drop in pressure because each fixture is fed individually" Well, in a rural situation involving well water, it really doesn't matter, since there is only so much pressure and volume available anyway. A lot of folks who have issue with pressure are located on municipal systems and using older, very high flow fixtures. In that case, when you are taking an 8 GPM shower at 100PSI, you WILL be quite aware when somebody cranks a 5 GPM kitchen faucet wide open. In modern rural plumbing, when you are dealing with low flow fixtures, low pressures and limited GPM this problem doesn't exist. Bottom line, is I have NEVER has a customer even mention water pressure, or flow issues, in any of my new homes.

The next big selling point is that you can "turn each fixture off as if it was an electrical circuit, just flip the switch at the panel. This makes it easy to do repairs" If you spend a few bucks to install 1/4 turn ball valves at each fixture, they can be shut off quickly, easily, and with no drama. Bottom line is that this "selling point" addresses another non-issue.

Finally, the process of running needless, individual supply lines for each fixture wastes hundreds, to thousands, of feet of PEX and often wastes valuable space in joist bays and wall cavities, making duct work and drain line installations more difficult.

Nothing personal, but IMHE, Manblocs and similar products address a problem that does not exist, and in doing so creates a lot of complication and needless expense.

[Rectifier]

All valid points especially in new construction, but to address a few reasons why I chose the system:
- I can pull all the pipes in with just one opened wall, already removed due to a burst pipe. To run a trunk line between fixtures/bathrooms I would have to open more walls to drill studs and I hate drywall more than plumbing.
- in our climate the greatest risk of failure is burst pipe due to freezing. As such having the shutoff before the pipe is valuable, as is having only a single pipe to replace in the event of failure. I lost a toilet shutoff this winter and had to shut off all water until I went to town for a new valve.
- all my pipe runs are ~20' or less from the manifold due to design of the house. With long runs I would not have considered it.
- as an electrician not a plumber I don't have to worry about pipe sizing or appropriate routing. 1/2" to everything

[wharton]

couple of point to address here.

First, on a remodel, I would never reinstall supply lines in an outside wall, period. There is some way to avoid this in most cases, and you will benefit greatly from doing so. Second, there are no burst pipes or failures in PEX piping due to freezing, fitting and clamps? It can happen, but it usually doesn't. It will expand when frozen, but the pipe itself is pretty much indestructible. As for shutoffs, IMHO at the source is about the least logical place to put them. As you discovered with your toilet situation, a quick effective disconnecting means at the fixture is what's needed when the toilet is overflowing, or a faucet is shooting water in an entertaining manner. Running down several flights of stairs to get to and finding the proper valve is a lot harder, and more time consuming that using a shutoff located where it belongs. In many cases if there is an issue when a wife or kids are home alone, there is little chance that they can, or will, go down and successfully disconnect the water at the manifold. If you tell a child, over the phone, to turn the little chrome thing under the toilet, until the water stops, you are much more likely to succeed. If you use stainless steel 1/4 turn ball valves they will be fully functional decades from now.

One of my competitors was head over heals in love with the whole Manabloc deal until ended up doing continual service calls for leaking manifolds, which involves shutting off the entire system, disassembling the stack and rebuilding the valve. Now he is back to the old school way, and glad that the whole mess is behind him. Faced with what you describe, I would run the individual lines to all the fixtures, avoiding any concealed fittings. I would use SS 1/4 turns at every fixture, and I would use inexpensive, non-valved distribution manifolds at the closest accessible point that I could gather all the hot and cold 1/2" supplies together, then run 3/4 to the water heater and incoming cold supply. I don't know if you ordered any of the 1/2" 90 degree pipe forming clamps, if not take a look at them. It is a plastic curve that hooks over the exterior of the pipe and permanently holds it in a nice, sweeping 90* bend. They can be really handy for remodeling. Good luck.

[Rectifier]

What I discovered at the toilet in fact was that the local shutoff valve had broken in two where it comes out of the exterior wall!
Probably expansion in the pipe from ice broke the weakest point, a corroded old valve. That experience set me on the whole "valved manifold" track.
I plan to have local shutoffs too as they are not too expensive. Hopefully i can find them in synthetic or SS. The only manifolds available locally are copper, so the manabloc was actually cheaper in the end and should last

I am relocating pipe from the exterior wall to the crawlspace, hopefully this will protect it? The crawlspace is heated with waste heat from furnace and domestic hot tank.

Thanks for all the advice I will look into the 90 clamps as I never heard of them. Sound like a good idea. I have seen what water can do to a house so I want to make sure there are too many valves rather than not enough.

By the way what was the cause of leakage in the manablocs, dried up O rings or something similar?

[NorthwoodsMike]

Originally Posted by wharton

Pipes sweating in the walls is a common misconception. Sweating occurs when the pipe is exposed to moist air. All penetrations into the wall cavity, drilled holes in plates, places where pipe exits drywall etc... should be caulked and/or fire sealed. If done correctly, there is no moist air in the cavity, and no sweating.

It really depends on how the pipe is run. In an exterior wall situation, humidity SHOULD stay out, but doesn't always. Electrical outlet boxes don't always have a tight seal. Bugs can create holes. While the infiltration may be minimal, it's safer to insulate. Also, many times cold water pipe runs next to warm. When insulated, you are more likely to get the water you want, vs lukewarm.

Originally Posted by wharton

(snip) Nothing personal, but IMHE, Manblocs and similar products address a problem that does not exist, and in doing so creates a lot of complication and needless expense.

I prefer a shutoff at both ends of the line. If something happens in the wall, it's nice to have.

Home runs typically also result in warmer water faster. Let's look at some math:

1 ft of 1/2in pex holds 2.355 cubic inches of water. With a 30' run, there is 70.65 cubic inches of water in the pipe.

1 ft of 3/4in pex holds 5.299 cubic inches of water. With a 25' trunk, plus a 5' branch, there is 144.24 cubic inches of water in the pipe.

In other words, you need to run your hot water twice as long to get full temperature, assuming no other fixtures are being actively used in the trunk situation.

Just something to think about.