PEX Plumbing Question

[a]

I am planning to re-do the 'cobbled together' plumbing in our home and am considering PEX. I hear that PEX is easy to install (which would help us when we have to run pipes up existing walls).

The existing system used 1/2" copper (and 70 year old galvanized iron pipe) & was run in a 'straight line' fashion. e.g for the 'cold' line from the kitchen sink, to rear outside tap, to bathroom sink, to toilet, to cold water inlet, to bathroom tub, to hot water inlet, to the front outside tap.

I see one way to install PEX is with a manifold system - where 1/2" PEX pipes run off of a manifold to each appliance. Apparently that method allows for less 'shower shock' - and, if you use individual appliance shut-off's - allows for servicing individual appliances.

The only troulble with it is that we see is the cost of the manifolds and the individual shutoff valves. We very seldom have to turn the home water off for repairs so we think the individual shutoffs is kind of overkill.

Instead of the manifold system - could we do it in the 'straight line' fashion - using 3/4" PEX? Or is there something we are missing?

[BobK207]

I'm no PEX expert but I've got al the tools & have read a great deal about the stuff.

I'm real old school, always have used copper tube for new & repair work. I'm just about to take on a re-pipe (80 year old galv) & PEX will be my choice.

I've been thinking about the two methods & I think I've settled on the manifold / home run system. At first I thought it was rather wasteful but I think it's the correct way to go.

yeah the manifolds are a little pricey but all your starting connections are made in the same place & you just run tube to fixture. All your runs will have no hidden / unservicable joints. You'll save money on fixture located shutoffs.

If your're handy with a torch you could build your own manifolds with shutoffs.

here is a source for manifolds with built-in valves

no you're not missing something, you CAN do it with 3/4" straight line but I think you'll be gving up some of the advantages of PEX.

system performance will depend on usage & home layout. I have a mdeium sized ranch house that I almost re-piped w/ PEX. I was going with two sets of manifolds

near the laundry & kitchen near the remote bath cluster

I was even thinking about a hot water loop to the remote manifold; water temp & timer controlled. I was tired of waitng 135 secs for hot water!

btw I already re-piped the street to house main (1" copper two years ago) & all yard water in 1"PVC. I've got awesome flow anywhere in the yard. No more house mounted hose bibs.

The house flow is a joke, takes about 15 minutes to fill the washer and forget about running two fixtures.

I've yet to take the plunge and actually do a PEX re-pipe, so everything I've mentioned has only be my thoughts on the subject.

cheers Bob

[Tony Hwang]

Hi, Manifold all the way. That's all they use in our area on new houses. I used it when I built my cabin. Neat and easy to work with. IMO, PEX is good stuff in cold or hot. Tony

[Rudy]

Thats how our current house is done but the manifolds (one for HOT, one for COLD) have no shut off valves on them. Inline shut off valves in each cabinet

Yes, that works too. Thats how our last (1998) house was done..1" to3/4" Pex, dropping down to half inch for each final line. Angle stop shut off valves-No manifolds.

R

[Brian]

I just saw at @Menards they started to carry pex manifolds.

Copper 8's for 1/2" pex with 3/4" supply, and shut-offs are $49.95. Not terribly bad.

Local plumbing supplies also sells 'em pretty cheap. Our plumbing supply carry almost entire line of Wirsbo Pexs, and prices would beat

30% below lowes, and HD.

[Martino]

Are we talking here about:

- one hot and one cold tube per appliance (like shower) or

- one hot and one cold tube per bathroom (like shower, bathtub, lavatory, toilet) and then split per appliances or

- one tube per section of the house (like 2nd floor west wing) and then split per appliances or event rooms at first and appliances later?

Interestingly I just did a quick cost comparo and it looks like the material price is not much different between the different approaches.

If I used method one; would it be of any benefit to me to shut-off water access to appliances I am not using long term; like guest bathroom?

Cheers

[MC]

I only use CPVC (and PVC for some cold only use) and main line

Never had any problems.

[CR]

Yes, you can run it "straight" on through but having a manifold is a better way to go. Each system in the house can be tested as it is finished and left on while you work on the next. If at sometime someone, somehow, someway damages a line or you have to replace a leaky stop, you can turn off the one system at the manifold and the rest of the house never knows it. This is a feature that I like because I can just shut it off and then drink beer and watch football all weekend and wait until Monday to fix it. You have to think ahead.

The only down side to Pex is the price of the tools, a plumbing supply house here rents them for $25 a day, which I thought was reasonable.

CR

[Edwin Pawlowski]

Only problem with a manifold system is that he is re-doing an old house. If the layout allows it, yes, great idea, but sometimes with old homes it does not work out that easy. Then you do what you have to do.

[CR]

True, but if you use a manifold and something breaks, you just shut it off and then do what you have to do. You know, like drink beer and watch football until you want to fix it.

CR