NGC: in-line AC thermostat

[Testarossa]

I'm sure someone here can solve this simple problem.  I'm happy with DC circuits but 240vac makes a coward of me, and when frightened sometimes I don't think straight.

The electric baseboard heater in Gail's studio won't turn off, so I pulled the circuit breaker and took the thermostat off the wall. The original Mears unit (at least 25 years old) is out of production so I ordered a modern two-pole Honeywell CT410B.

The Mears has three wires: Red for line, black for load and white for neutral, which confuses be because I thought you get a neutral wire only with 110v circuits. The Honeywell has four: L1 and L2 for line (red), T1 and T2 for load (black). I assume the line wire (black) from the box should go to L1 and/or L2.

• Should I twist the line wire together with both L1 and L2 (red), or just one of them? 
  Should I twist the load wire (black) together with both T1 and T2 (black) or just one? 
  What do I do with the remaining white neutral wire from the box?

Any help?

[Kiwi_Roy]

Its using the line and the neutral for the control circuit as 110 Volts, may have hat a relay or some electronics
I think the Honeywell is just a simple mechanical device.
If the Honeywell doesn't require a Neutral just tape it up or put a marette to stop it shorting something out

How to wire it?, that depends on how the heater was originally wired, did the electrician wire it as single pole or 2 pole?
Could you take a picture of the electrical box showing the wires.

I should mention I'm an industrial Electrician, house wiring is not really my thing.
If I was doing it from scratch I would run the two wires from the switchboard to L1 & L2 with the switch wires T1 & T2 going to the heater terminals.