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Glad I found this site, happy to be on here and I look forward to learning from the crew and sharing.

In any case, I'm in the process of buying a four family. I have it under contract, am buying at a discount because I understand it needs a good bit of work, and the price tag for having someone replumb all the supply lines is such that I'll figure it out and spend a month doing it.

In any case, again, I'm just starting this process and was over there studying the current plumbing system today. It is absolutely ridiculous and this will be a major system upgrade that needs to be done at some point anyways, and if the city comes through they'll be making me do it...

House was built 1890, so the plumbing is a total hack job done piece-meal. Combination of copper, galvanized steel, and PVC. At this point I don't want to address the drainage unless it's hard to ignore when I'm opening things up (which it might be).

So I have a lot to read about supply line diameters, velocity, etc., etc., but as I'm starting to brainstorm about where to put the system and manifolds and start building out from there, I had some simple questions.

First, some details about the house: bathrooms are all back to back on top of one another, so this will mean that tearing out one wall will give me access to the other bath across the hall as they more or less mirror one another. The kitchen supply planning is a little more difficult, but they only need supply lines for the sink. No dishwashers.

So, my initial though process is that I'll need one master manifold with 15 valves. 3 per unit = 1 kitchen, 1 bath, 1 to hot water heater. Total 12 for cold water unit supply. Then 1 for washer and 1 for hose. Plus an untapped valve for pressure testing should I even need to check.

Then off the hot water heaters I'll need simpler manifold with just 2 lines (or one will have to have an additional line for the washer).

Again, I'm early in the planning stage, but does that sound about right? Additionally, what type of manifold would be the best way to go about this? I saw some guy on youtube (who was a legit plumber) build a circuitous one which maximizes water pressure (as he explained). That way it could be easily customize with the right number of valves. It also sounds more complicated.

Alternatively, I could purchase two closed copper manifold with 8 ports and branch the main supply to the two, and kick out from there.

Any advice as I begin planning this project?

  • I take it that all four units share a common laundry facility, and that it's a master metered complex? Do your locale's plumbing code and your water utility's rules allow for master metering, or will they require you to convert it to individual metering? – ThreePhaseEel May 12 '17 at 3:16
  • Thanks for the response. Laundry facility is shared, yes. It is also master metered. I think master metering is permitted as in my locale the owner almost always pays water and sewer. I'll check tomorrow, however, if the individual metering is required. – JTM May 12 '17 at 3:25
  • Why are you running a single line to each bathroom? One of the significant advantages of PEX is no connectors hidden behind walls. With one line to each bathroom, you'll have to split at the bathroom. – longneck May 12 '17 at 14:16
  • Longneck, does it make sense to do otherwise? 4 fixtures per unit off the cold manifold, one hot water line, plus a few extras, I'm at a master cold manifold of 22-24 lines. Plus hot water manifolds for each unit with 3 valves. Is splitting in the bathroom really that much of a problem? It's a Homerun vs. a branch and trunk system (from what I've read), and there's debate about it. – JTM May 12 '17 at 19:46

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