Sizing water pipes to and from hot water tank

Hi guys!

I am running new pipes in the basement before I close all walls with drywall.

Right now I have the following set up:
5/8 copper service to a 5/8 water meter, down to 1/2 copper after the meter, and then 1/2 pex to hot water tank and 1/2 from hot water tank.

I have 2 full bathrooms, 2 kitchens and 2 washing machines.

My plan is to run 3/4 pex after the water meter, with two 1/2 take offs from the cold pipe to different fixtures, to the water tank. Also, run a 3/4 hot water pipe to the 2 nearest 1/2 take offs to fixtures. Btw, by local code (Ottawa, Ontario), I have to have a hot water mixing valve installed.

Or should I just run 3/4 cold to the water heater, and then just go with 1/2 pex from there?

What do you think?

Thanks!

 

I'd run 3/4" pipe for all your main lines. Branch off to the various fixtures/rooms in 1/2", and when you get to your last branch, branch both as 1/2". Keep it simple, but make sure you have enough volume everywhere you need it!

 

I run 3/4" PEX trunk lines and come off with 1/2" to feed each fixture. 3/4" x 3/4" x 1/2" T fittings make the job really easy and you have good flow to all your fixtures.

 

Is there really such a think as 5/8" copper?

 

Thank you for your responses.

Yes, the house is 60s construction so the service pipe is 5/8 copper, they don't even sell those anymore. This is why I would like to expand to 3/4 pex because the inside diameter of 3/4 pex pipe and fittings is close to the inside diameter of 5/8 copper.

So what I will do is run 3/4 pex after the water meter, with 2 main 1/2 " take offs before the 3/4 cold pipe reaches the HWT, then run 3/4 of hot pipe to the nearest 1/2" takeoffs to two bathrooms, kitchen sinks and washers.

 

Sounds like you have a good plan forward. Let us know how it goes!