Running radiator supply lines across garage ceiling

[dave11]

About half of my house sits above a 750 SF unheated garage. I'm penciling out a plan to add hot water radiators to those five rooms, but the only way to run pex or copper supply/return lines to those rooms would be across the ceiling of the unheated garage. It seems most people recommend a home run system in this situation normally, but I'm wondering if a two pipe reverse return would be better, as it would lead to less piping and less heat loss to the unheated garage.

Also, pex is more resistant to freezing, but since these would be pipes for heating, I'd assume they'd never freeze unless the system wasn't working in cold weather. The ceiling is low and the garage is busy, so I'd prefer to use copper, but could use pex if it made more sense in this situation.

So my questions are: two pipe vs home run, and copper vs pex.

Thanks.

 

[E Yoder]

What about pex inside a 2 or 3" PVC conduit to keep it straight?

 

[maple1]

What about pex inside a 2 or 3" PVC conduit to keep it straight?

Hmm, you just accidentally helped me with a water pipe issue under our cottage, with that idea.

 

[dave11]

Do you mean--use a pvc sleeve to help protect the pex from damage?