Verify cold water design

[Russell Harris]

Hello,
I'm looking for input/suggestions on changing out both cold and hot lines in my 1952 pier and beam house. This post mainly deals with the cold water as that is where I need to start given my service entrance.
- 3/4" copper from meter to old galvanized as it enters the house (pic)
- I'm questioning if I can use 3/4" PEX from the 3/4" copper service entrance
- Is there a benefit to using 1" PEX from the 3/4" service and then changing the manifold to 1" x 1/2" out and use 1" x 1" x 3/4" tees for the WH and addition? (see diagram)
- The hot water from the water heater I was going to make 3/4" PEX to the hot water manifold then out to the various locations 1/2"
Anything is going to be an improvement as I can only imagine the buildup in the galvanized cold water lines.
Please ask if I have not provided enough information. Any advice is greatly appreciated!
Thanks!
RH in Austin

View attachment 61927

 

[Russell Harris]

Ok, I'm going to reply to my post to see if I can get a bump/response. I'll boil it down to just one question.

Would I benefit in ANY way from using 1" PEX-A (Uponor ProPex fittings and manifolds) pipe to connect to the existing 3/4" copper water supply?

Or should I just stick with 3/4" PEX-A to match the incoming main supply?

(please see diagram in post above)

Thanks for any advice!
RH

 

[Sponsor]

 

[Reach4]

Yes to your first question.
1 inch pex will have less pressure drop than 3/4 inch. Pressure drops add, rather than being determined by the smallest pipe.

Also, 3/4 inch pex is smaller than 3/4 inch copper.

On the other hand, 1 inch pex is stiffer. If your expansion tool is a hand tool, it will be harder to expand than 3/4. If it is a good power tool, you won't need to worry abou that.

 

[Russell Harris]

Yes to your first question.
1 inch pex will have less pressure drop than 3/4 inch. Pressure drops add, rather than being determined by the smallest pipe.

Also, 3/4 inch pex is smaller than 3/4 inch copper.

On the other hand, 1 inch pex is stiffer. If your expansion tool is a hand tool, it will be harder to expand than 3/4. If it is a good power tool, you won't need to worry abou that.

Thanks Reach4! I initially didn't understand the notion of what you said about pressure drops add but did some Googling and now I get it.

I'll go with 1" PEX into the house from the 3/4" copper in the yard and then keep it 1" to the single manifold and the addition and the WH. And I did just pickup a Milwaukee M12 expander tool on eBay today!

I appreciate the advice!
RH

 

[Russell Harris]

One thing I'm trying to figure out, the best way to get from 3/4" copper pipe to a 1" PEX-A fitting. I thought there was a brass sweat adapter from 3/4" pipe to 1" PEX but can't find one. Am I missing it? Putting a sweat fitting on the street copper would be my preference as this will be outside in a valve box, in ground.
RH

 

[Terry]

The make 3/4" to 1" copper couplings for soldering.
The sooner you bump up a size the better. It's about friction loss.
Also since PEX is the same OD as copper, the inside dimension is smaller and passes less water and has more friction loss.
For a three bath home they sometimes require a 1-1/4" PEX line to a 3/4" meter.

 

[Reach4]

Elkhart 30556

I think it would go into a 1 inch aquapex C to F1960 adapter.

But you check.

A 1" x 3/4" Copper Coupling would take a 1" ProPEX x 1" Copper Fitting Adapter

And if you wanted to do something like mount something that could mount a pressure gauge on occasion, such as a boiler drain, think about a reducing tee.

 

[Russell Harris]

Elkhart 30556

I think it would go into a 1 inch aquapex C to F1960 adapter.

But you check.

A 1" x 3/4" Copper Coupling would take a 1" ProPEX x 1" Copper Fitting Adapter

And if you wanted to do something like mount something that could mount a pressure gauge on occasion, such as a boiler drain, think about a reducing tee.

Ah ok, thanks guys! I actually came across a small bit of 1" copper pipe so I think between that and buying the fitting Terry mentioned and then a F1960 adapter I'll be able to make up a transition. In addition to adding the cutoff ball valve.

Once again thanks for your help!!
RH