Description:
Wiring:
Coming from the wall: 2 white (on the right side) and 2 black wires (on the left side) and no 5th wire (ground) that I can see. The wall wires are single strand copper.

Wiring:
The new thermostat (LUX brand basic 120/240 double pole) has 2 red wires = Line 1 & 2 (on the top) and 2 black = Load 1 & 2 (on the bottom) and a screw for the ground attachment. The wires are multiple strand aluminum.

Question:
1) What wire attaches to what color on the new thermostat?
2) What if there is no ground wire in the wall?
3) Can I attach copper to aluminum or do I attach the copper directly to the posts and not even use the short thermostat (red and black) wires provided.

Thank you,
TS

What wire attaches to what color on the new thermostat?

Follow the directions. It makes no difference as long as you do not short the different legs of 220 together.

What if there is no ground wire in the wall?

Bad news all units should be grounded with a green or bare conductor back to the service panel. Replace wiring or repair.

Can I attach copper to aluminum or do I attach the copper directly to the posts and not even use the short thermostat (red and black) wires provided.

Copper and aluminum do not get along well together due to the different expansion and contraction properties. Special connectors are available for that purpose. Direct to the posts sounds sounds good BUT the wires on the thermostats are probably not aluminum to start with. Did you test the wires or read the printing numbers letters on the wires to see what they really are made of.

I think you posted earlier on this basic subject.

The t-stat wires are not likely aluminum, but rather tin-plated or silver-plated copper.