Hot Water Recirculation through shower cold line?

[nikg]

First time posting. I am renovating our master bath and re-doing a lot of the plumbing for sinks, tub, shower as all of these are being relocated within the bathroom. The master bath is all the way on the other side of the house from the water heater, so it takes a very long time to get hot water in the sink and shower. After a little research, it seems a hot water recirculation pump on a timer like the Watts 500800 is probably a good solution. However, if I understand correctly, the way it works is by using the cold line as a return, so you don't get cold water until the hot recirculated water is flushed from that line. So now this creates the same problem of wasting water waiting for cold to do stuff like brush teeth or wash hands in hotter months when you want cold.
Questions are:
1- Is the cold water "flush out" a big problem? Does it take just as long as waiting for hot?
2- Since I am doing everything new, is there a way to locate the "under sink" bypass valve somewhere else in the system or instead of connecting the cold end to the sink cold line just run it to the cold line of the shower or tub where we almost never want pure cold water anyway?

Thanks

 

[GReynolds929]

If you're going to have walls opened up to move and redo plumbing, I would run a dedicated line back to the water heater, instead of using the crossover system.

 

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[nikg]

If you're going to have walls opened up to move and redo plumbing, I would run a dedicated line back to the water heater, instead of using the crossover system.

Is this easy to do? I'm assuming that involves a very long run all the way back. What kind of valve would that require? Or would it just be like some kind of t-fitting or something?
I was thinking kind of the same concept but being more efficient by just using an existing line close by such as the shower cold line. Just tap into that one because we essentially never want full-out cold from the shower. But if the dedicated line is better then maybe I just do that. I'm sure there is already a thread on this topic...could somebody point me in the right direction?
Thanks

 

[Breplum]

You should run a dedicated return off a tee near the end of the hot run. Hire a professional. Insulate the supply and the return and use either a Grundfos Comfort system or pump of your choice and Smart Recirculation control like: https://smartrecirculationcontrol.com/