Hot water main 1/2 inch? Update system

[8seconds]

Running Pex A to replace old galvanized water line. I noticed that my main incoming is 3/4 inch, but coming out of the water heater it is 1/2 inch. I did a little research and found this was common practice (less cold water to flush) and helps to get hot water to a fixture quicker. Given I am going to replace the system, should I just replace the same diameters using the existing trunk and branch or would a manifold or sub manifold system be a better option.
Water flow is adeqaute and I will not be putting in any high demand fixtures.

 

[Jeff H Young]

I would run 1/2 inch if just feeding a lav and shower , no bath tub and flow was no concern. Thats old school work Thats how they did it the first half of last century It works . just like a 57 chevy with a powerglide it works. 3/4" minimum my opinion

 

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[wwhitney]

To the OP, depends on how many hot water fixtures and how far away each is from the water heater, and how they are grouped in proximity. Please specify.

Cheers, Wayne

 

[8seconds]

To the OP, depends on how many hot water fixtures and how far away each is from the water heater, and how they are grouped in proximity. Please specify.

Cheers, Wayne

The main bath is 50' of pipe run to the water heater. The second bath is 25' of pipe run. Kitchen and laundry are with in 10' of WH (kitchen upstairs, laundry in basement). There is a tub in the main bath, but only a shower in second bath. Each bath has only one vanity sink and faucet. There is a noticable differance in time to get hot water to the bath that is 25' away vs the kitchen sink.

 

[Jeff H Young]

I usually run 3/4 to a kitchen D/W and wash machine (who knows might even have a laundry sink) and a bathroom 50 foot away using pex 1/2 inch? Im telling you no bueno thats not good work. adress your time waiting for hot by either relocating your water heater or more likely a recirculating system and pipe to proper sizing

 

[Sylvan]

Why not run 3/4" all the way and at the last fixture reduce the supply to 1/2" and run the 1/2" back to the water heater for return circulation?

This will save water and time as now you do not have to wait for the water you already paid to heat up again

 

[8seconds]

I usually run 3/4 to a kitchen D/W and wash machine (who knows might even have a laundry sink) and a bathroom 50 foot away using pex 1/2 inch? Im telling you no bueno thats not good work. adress your time waiting for hot by either relocating your water heater or more likely a recirculating system and pipe to proper sizing

That is what they originally did 60+ years ago. I guess that is why I asked about re-configuring the system. No way to relocate the water heater. Could you just do a manifold recirc system for the hot water side?
I may have another issue with the PRV system. I see the PRV is at the end of the cold water system right before it goes into the water heater. I need to check with a pressure gauge to verify the main pressure, but cant figure why they would put it there instead of at the house entry point. The cold side branches to all the fixtures before getting to the PRV? It has worked for many years, but I think this is not set up correctly.

 

[Jeff H Young]

Sure a recirc system for the hot. if you want to run 1/2inch pex 50 ft to a full bath have at it it will work water will still come out the end its just not right Pex is already small and if you use those crimp fittings they are even smaller on the inside than expansion fittings.
PRV could mean pressure relief valve ? but a pressure reducing valve is very differant with same initials
Never seen a pressure reducing valve only regulating water to the heater that would be wrong

 

[8seconds]

Sure a recirc system for the hot. if you want to run 1/2inch pex 50 ft to a full bath have at it it will work water will still come out the end its just not right Pex is already small and if you use those crimp fittings they are even smaller on the inside than expansion fittings.
PRV could mean pressure relief valve ? but a pressure reducing valve is very differant with same initials
Never seen a pressure reducing valve only regulating water to the heater that would be wrong

Not sure I understand, you stated "I would run 1/2 inch" earlier (post #2). There is 50' of 1/2 inch galvanized going to it from the original build. All the hot water lines in the house coming out of the WH are 1/2 inch original. Are you recommending running 3/4 from the water heater and a sub manifold closer to the full bath? Without moving the water heater sounds like I will just have to put up with the hot water lag time.

I will take a pic of the valve going into the water heater and post.

Thanks for the advice.