Aluminum-Copper tubing

[Makeit go Right]

Saw a couple of ads about this new construction of tube for aircon/refrig systems and wondered if anyone has been using it yet and what are their experiences with it.

AFAIK, these two metals have different co-efficients of expansion, so will expand/contract to differing lengths when heated/cooled. And that constant stress going on during the life of a system, repeatedly expanding and contracting, must take it's toll before too long.

And if used on an air heat-exchanger, doesn't the ali tarnish in a different way to copper and reduce heat transfer?

Guess it's a bit early to answer these questions but maybe someone already has come up against it(?)

[monkey spanners]

Seen the adds, don't see whats wrong with copper on its own really.

Seems to me the only thing its got in its favour is price and i've never been one to buy on price.

Jon

[JoeAT50A]

Galvanic effect caused by Aluminium reacting with Copper and impact to the system is uncertain.
The strength of Aluminium pipes are uncertain compare to Copper pipes that had been in use for decades.
Copper has a high thermal conductivity of 400 W/mk compared to 237 W/mK for Aluminum.
So CU is the winner but expensive than AL.

[desA]

I've seen aluminium tubing, with copper flash outer layer - in Asia. Knocks the bottom out of pricing for Asian systems. The copper flash layer allows usual brazing techniques - if you're careful.