3/8" supply line to house, 1/2" manifold for homeruns?

[Jebusfreek666]

I am in the process of renovating and updating my entire house. Currently, I am looking into redoing the entire water supply runs as there are no outside water bibs, and I am adding a bathroom and moving around the kitchen. Due to these changes, I would like to switch to a manifold system. The issue I am researching now is the subject of this post. My house is about 120 years old. The supply line in the basement from the city appears to be 3/8". The best manifolds that I see that have the number of outlets I need, plus a couple for expansion if needed, are all 1/2 inch in/out. Can I use these manifolds? I realize I can use an adapter to make the inlet on the cold side 3/8", but doesn't that completely negate the benefits of using the 1/2" outlets and PEX? I also realize I can still do 1/2" from the water heater to the manifold. But that water heater will still be fed originally from the 3/8" cold supply line.

Basically, am I okay with this setup or should I be looking into getting 1/2" supply line to the house? It will be a 2 bath when I am done, one with both tub and multi-head shower.

Thanks!

 

[Reach4]

I realize I can use an adapter to make the inlet on the cold side 3/8", but doesn't that completely negate the benefits of using the 1/2" outlets and PEX? I also realize I can still do 1/2" from the water heater to the manifold. But that water heater will still be fed originally from the 3/8" cold supply line.

Not totally negated, but largely negated. I would pipe the inside as if you are going to get that supply line replaced in the future. While piping, you might add a boiler drain valve early in the path where you could mount a garden hose thread pressure gauge to see just how much drop you are facing on the incoming water with flow.

Basically, am I okay with this setup or should I be looking into getting 1/2" supply line to the house? It will be a 2 bath when I am done, one with both tub and multi-head shower.

If you are going to get the supply line to the house replaced, I would go at least to 3/4. Most would run 1 inch.

I never heard of a 3/8 supply line to a house.

 

[Sponsor]

 

[Bruce Garrison]

3/8" is really small. I think you need to double-check what your supply line size is. I have a 2" copper pipe for my whole building that branches to a 3/4" for my unit. The PEX manifolds I use are 3/4" that branch to 1/2" for each fixture.

 

[Bruce Garrison]

BTW if you are using PEX supply lines, don't make the mistake I did and use the standard PEX-B compression fittings that they sell at the big box stores. The flow is atrocious. Special order or go to a supply house and get PEX-A and use expansion fittings. The difference is more than noticeable. I am having to replace all this garbage I bough from HD because once I turned it on the shower felt as if someone was spitting on me the pressure was so bad. The previous plumbers had wisely used Rehau PEX-A expansion fittings and all was well. Then I remodel and use PEX-B for the additions and it is terrible. If you doubt me, look at page 6 of this.

 

[Jadnashua]

120-years ago, who knows what was standard...I think that they were just glad to have running water that they didn't have to carry from the pump.