Hot Water Recirc Systems

['Stormin]

Can someone explain why a "Demand" type system is NOT a cross connection of hot & cold sections of my plumbing?

I want to install a "recirc" system and am biased towards a loop system instead of "demand" system installed at furthest fixture group.

Doesn't this type of system introduce the possibility of ingesting water from HW tank (even if for an extremely short time period)

Where can I get more than just the very basic info on a HW loop system? How much can the "down side" of massive heat loss can be mittigated with incredible amounts of expensive foam pipe sleave insulation combined with burrying hot water line in the middle of fiberglass floor insulation of crawl space?
Talking about 3/4" pex loop well under 120' total length with remote 1/2" manifolds at fixture groups.
Thanks.

[PLUMBER RICK]

a demand system is usually used as an afterthought when there is no hot water return line.

the cross you're referring to is no different than a what you have when you hook up a water heater. there are check valves built into the manifold.

it's a good system with little wear when you have no other choice. the ones i've installed for owners are happy with the results.

rick.