Garage Heater Wiring Plan

My new-to-me Cadet #BH752 electric garage heater needs a new wall thermostat and 220v connection. The unit is 17-1/2" high x 16-1/2" wide x 12" deep and has a heavy gauge steel swivel/tilt mounting bracket. It will hang from the ceiling in one corner of the new shop. The unit draws 240v and 31 amps for 7.5 KW. The fan motor is a Dayton 1/50 hp. I bought it off Craigslist for $75 from a guy in Wasilla. Manufactured in 1983, it looks pretty much unused since 1985, the year it was disconnected. When I opened it up, I was struck by how much wiring it had. It took awhile, but I was able to figure out how best to wire it in.

Parts Used

- Double-pole, 220v, 4-wire, non-programmable thermostat w/ OFF setting (Honeywell Home CT410B, $18)

- #6 aluminum (SE wire), I'll only use 3 of the 4 wires; 35' feet needed ($25)

- 40A breaker

- Knock out connectors

- J-box w/ cover

- Single gang box for thermostat

- Flex conduit w/ connectors (~4 feet) w/ connectors

- Wire nuts

- Ground screw (?)

- Electrical tape

- Long wire staples

-NoAlOx shmoo

I think this is how it should go, but change the wire gauge to #6 and breaker size to 40A based on the answers to these two questions...

Question #1: Line power comes in at left into terminals 1 and 5. But I have two dangling wires (for a single pole thermostat that has been removed) which I don't know what to do with. In my plan, I'm bringing power from the panel through the thermostat (line voltage) to the heater. How to deal with these "extra" lines?

Answer: Connect the two wires for "Single Pole Thermostat" together w/ a wire nut.

Question #2: The heater draws 31 amps. Will a 30A breaker work or do I need a 50A breaker?

Answer: #10 gauge wire handles 30 amps, while #8 wire handles 40 amps. This unit pulls 31 amps, so I'll go with a 40A breaker and slightly oversized wire - #6 aluminum SE 4-strand cable in gray jacket. The take home lesson for me is that #8 gauge wire is kind of no man's land. #10 and #6 wire are very common and widely available, but #8 doesn't come in Romex (at least it doesn't near me) and is pretty much irrelevant. And while I can probably run separate #8 THHN stranded copper wire inside EMT conduit, that's a pain and a clunky solution. The #6 SE cable behaves like Romex (several wires in one jacket), is cheap, and is available everywhere.