Re-locate water heater - does this move work?

[gthomson]

I'm looking to change out my 20 year old water heater (thought it was 18, but time flies...) And want to replace it with a tankless, and possibly re-locate it from inside the garage to outside the garage about 20' away on the other side of the garage.

I did a crude photo of what I'd like to try to do...

The blue circle on the left is the input to water heater below it.
The red X next to it would be capped off.
The water line would be run up into the attic instead, and over to the right side of the house. The external tankless water heater to be there. And then it would put the hot water out, to be run over, and tapped in, to somewhere that makes sense, by the two bathrooms where the red circle is.

The main water comes in just to the left of that wall to the left of the blue circle.

I don't understand the flow of the water in the pipes behind the walls.
Have only torn out one room of drywall so far to understand what goes on behind there better so far, and no plumbing there

Is this a simple re-route of things, but it's still a closed loop?
Or in doing this kind of thing, am I somehow interrupting the normal flow of the water through the pipes in a bad way?

Is there a good online animation graphic that helps show how this all works, or is every house (tract of houses) pretty much unique in how they have gone about it?
Anything like this - [ame]https://www.youtube.com/watch?v=fTAUq6G9apg[/ame] - for how the plumbing works in a house?

 

[havasu]

Is the tankless gas or electric? You first need to check your code and understand the installation instructions on the tankless water heater. If natural gas, do you have enough pressure/volume at the proposed site? Does your bathroom have windows? Many tankless water heaters prohibit installing their water heaters within 4' from any window.

Years ago, I moved my tanked water heater from the garage to a better outside location. It was a great move but needed assistance to calculate natural gas volume/pressure, and since I was re-piping my entire house, I really was not concerned with flow mapping.

 

[gthomson]

Thank you havasu, that's very much what I'm looking for - questions to ask.
That outside wall is a 'utility wall' for me - gas meter, breaker panel, A/C units, etc... along that side. So I'd very much like to move things there if I can - water heater, whole house water filter, etc..
Neighbors are down level a grade (not sure if that's the right lingo ), so what I do up to about 7' is mostly non-visible to them on that wall.

I'm okay with it staying in the garage, or moving outside - both have their pros and cons. Just wanting to better understand those so I know what to ask to get the right setup in the end.