Return to the Plumbing Forum | Post a Follow-Up

Planning PEX Pipe/Manifold

Posted by eferrini (My Page) on
Tue, Dec 27, 11 at 13:59

Hi all,

I'm looking for some advise on planning my PEX project. I am planning to use a home-run system with copper manifolds (1/2", 12 cold, 6 hot)).

I figure that I'll buy the copper manifolds with the 3/4" inlet. However, the main water line to my house was replaced last year with 1" PEX coming into the house. From there everything is galvanized that I'll be replacing with PEX.

Is it okay to continue the 1" PEX pipe all the way to the hot water heater, then split the 1" into a 3/4" to the water heater and 3/4" to the cold PEX manifold, then run the hot water heater 3/4" over to the hot PEX manifold? (so basically, is it a bad idea to split the supply line before it gets to the manifold, even if it's a 1" line?)

We are in a 1,000 sqft house with 2 bathrooms. Is it overkill for me to run 1" pipe at all? Would a 3/4" main line that then splits to the hot water heater and cold manifold work out just fine?

Thanks for your advice as I start my PEX project. I am looking forward to getting started.


Follow-Up Postings:

RE: Planning PEX Pipe/Manifold

Yes, you can run 1" to the water heater and make the split as you describe, however, before you do anything towards desiging your PEX system I would strongly advise you to download a free copy of the PPFS (Plastic Pipe & Fitting Assoc) PEX Installation Manual.

The manual is a free download in PDF format and it will not only answer your immediate question, it will give you all the tables and design parameters to correctly design your system. Handbook_draft_rev_2008.pdf

RE: Planning PEX Pipe/Manifold

Thanks for the suggested reading. I found a good basic installation guide from Zurn. I'll take a look at this one, too.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Plumbing Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here