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Upgrading to PEX

I have a small house that has a rat's nest of copper piping that's been patched and extended and capped over the years. I'm doing a kitchen remodel and heating system upgrade (switching from air to hydronic), and have decided to just rip it all out and switch to PEX.

I am planning not to do a manifold because the house is tiny, but rather a 3/4" trunk with 1/2" branches to the fixtures.

However, every pipe in the house is 1/2" at the moment, including the pipe that connects the main shutoff to the inlet of the water meter. I'm pretty comfortable changing out the pipe at the outlet of the meter, but should I change this inlet pipe to 3/4" copper to match? Seems like a real bottleneck.

Or maybe I don't NEED 3/4" and should just stick with 1/2" everywhere?


Re: Upgrading to PEX

I'm sure you'll get advocates on both sides of the ledger on this issue.

The trunk lines from the water meter, as you note should be 3/4"---then 1/2" to the fixtures.

I prefer copper because of its neat appearance & low cost of its fittings.

On the other hand, if you live in a northern climate, PEX is much less likely to burst if the house loses heat in freezing weather.

Since the cost of copper has shot up in recent months, nearly everyone is using PEX for such things as new distribution lines for a HW heating system.

Re: Upgrading to PEX

Usually the water feed to the meter is one of two sizes .... the older 5/8 inch or the more common 3/4 inch.
It's not uncommon to see the transition downsized to 1/2 inch copper with the 5/8 couplings attached to inlet of the meter and 1/2 copper feed for the home from the outlet of the meter. Sometimes this is done to maintain a required pressure level but this can have an impact by reducing the gpm flow.

If the incoming water pressure can be maintained at a reasonable pressure of around 50 psi with 3/4 inch feed that would be an ideal situation.

I agree with JacktheShack ...... having the 3/4 inch tubing for the main feed trunk and the 1/2 inch tubing for the branches would be nice for providing good flow distribution .... proving the supply can support this.

The other thing is in a smaller home .... if the distance of the run is reasonably short then the 1/2 inch trunk and branch may be reasonable with little impact of flow distribution.

Just a thought. :)

Re: Upgrading to PEX

Thanks for the insight. I think I'll leave it alone for now, and see what kind of pressure I measure at the outlet.


Re: Upgrading to PEX

Define tiny, as in the size of the house. I did a PEX home run style system in my 1380 sq ft house. Built my own manifolds out of brass 3/4x3/4x1/2" tees and ran a 1/2" hot & 1/2" cold line to each of 4 rooms about 25' each, using about 225' total. Including fittings, & tool rental, the whole thing cost around $250. Originally there were 1" galvanized trunks running to the farthest room & it was taking 2 min to get hot. Now its 20 sec for any room. It was really worth it!
When I pulled permits for the addition this was part of, I was advised to go at least 1" pipe from the meter, that way the water line was upgraded for all future use. Did 1 1/2" & have no pressure probs. City delivery is pretty high pressure in my area, esp. being almost across the street from the well. If you can swing it, I would really consider a home run system. Don't buy a 20-fitting manifold, just make your own to suit your needs. Just don't forget to add shutoff valves everywhere you might want them, like to individual runs & a master before thy "manifold."

Re: Upgrading to PEX

About the 1 1/2" supply, the way the guy at the permit counter explained it, larger diamerter pipe is going to reduce wear on the inside of the pipe. Compare 1 gpm moving through 1/2" pipe. 1 gallon of water has to move quickly through the pipe. Now if the pipe was 1", it would move 4X SLOWER because 1" has twice the area of 3/4", which has twice the area of 1/2" pipe. Slower water movement is supposed to equal less wear on the insides of the pipe, but I am sure there are some experts here who can verify or refute that, as needs be.

Re: Upgrading to PEX

I think alot of the posts forgot the fact that he also plans to use hydronic heating with this system. And yea once the system is in place, it is seperate of the water, however using straight lines of PEX can look as nice as copper. And PEX-Al-PEX for heating will be betweeen the joists, but use the same tools. I think comming off the meter and then having a shutoff valse and a tee for a water pressure guage would be worth the few extra dollars and peace of mind.

Good luck. Process of elimination.

Re: Upgrading to PEX

CAUTION...This just in!

There are now law suits being filed against PEX just like a few years ago with polybutylene. As a home inspector I try and stay on top of current technologies and issues and I just had this sent to me this mortning and thought that I should pass it on to TOH.

Go To: http://www.zurnclassaction.com/?gclid=CKKEg5v2vpICFR8MIgod6BWNXA for further information.

Re: Upgrading to PEX

I've been checking in on this myself, my galvanized pipes need replacing.

So far I've received quotes from $2000.00 to $3500.00 to do the work.

I've worked with copper & cast iron pipe.
I think I can do it myself.
But any feed back or instructions would be greatly appreciated!
BTW: I heard of the law suits, the law suits are against Zurn fittings, not the PEX tubing it's self.
Check this site: http://www.zurnclassaction.com/

Re: Upgrading to PEX

thanks for the heads up on Zurn fittings,i personally refuse to use plastic for anything except drains,the prob now a days is the price of copper and home builders go for the cheapest cost,i cant compete w/the guys using plastic...but i can sleep at night..lol,if ANYTHING i'd rather see you use cpvc over a pex style compression fitting

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