Hot Water Re-Circulating Loop (Retrofit)

[naicidrac]

Hello all, I have a home built in 1986 with copper water lines and slab on grade. I have 3/4'' copper line running from my water heater into the slab and then 1/2'' copper lines running into bathroom faucets and kitchen. The kitchen is the last on the hot water circuit. I have timed it and the kitchen is last and it takes a VERY, VERY long time to get hot water to the kitchen. I have seen those retrofit kits at the big box store but I have tools and like to work so I wanted to make a dedicated retrofit return line back to my water heater and install a pump and do it right. I have access under my kitchen sink and the counters are connected to an interior wall. I wanted to connect a dedicated return PEX line and run it up the wall in the attic (Insulated) and back to the water heater with no junctions in the attic. I live in Texas and it gets cold but I was going to insulate the pex line well. I want to put a pump with a timer and most designs I have seen have the pump located down close to the water heater drain faucet and that is where the hot water is returned. My question is what size of PEX return line do I use? I was going to do 3/4'' but I only have 1/2'' coming out of the slab under the kitchen sink to the faucet. Would that be pointless to have a junction or manifold from 1/2'' then convert to 3/4'" return line back to the water heater???? Also, what kind of junction or manifold should I use. I have looked at some nice copper sioux chief manifolds with one 3/4'' connection and 2 X 1/2'' and they specifically say "Do Not recirculate back through any manifold branch"???? I am not sure what this means and wanted to ask you guys. Also, what recirculation pump do you guys recommend? Thanks so much!

 

[Twowaxhack]

1/2” pex insulated return. All you need is a tee to connect the hot water pipe under the K-sink, if you want to call that a manifold, ok.

https://www.supplyhouse.com/Armstro...MIutvQ3dbVhAMVym5_AB03pwbvEAQYASABEgIGj_D_BwE

 

[naicidrac]

Thanks! So 1/2'' will be plenty to return the water back to the water heater? Also, I think I understand what I was reading about manifolds. A re-circulating pump won't do anything for a manifold system and it must be a trunk and branch system which is what I have. I think I misunderstood what I was reading on the manifolds and I thought for some reason they would not work in what I want to do but it will be fine. Thanks for the info!


Here is an example of what I was referring to about the manifold. You can see in the description it says "Do Not recirculate back through any manifold branch". I am guessing that just means a manifold will not supply hot water any faster if you put a pump through it.

https://www.siouxchief.com/products...0-branch-manifold/3-4-f1960-x-3-4-f1960-trunk