help with 2 pole manual to digital thermostat install


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Old 03-10-07, 02:22 PM
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help with 2 pole manual to digital thermostat install

I'm in the process of replacing old 220v electric baseboard thermostats (honeywell t498B1512) with Aube/honewell TH115-A-240D 3600W 240v - 15A programmable digital thermostat. The old thermostat had l1 and l2 connections for the hot wires and t1 and t2 for the load connections. When I connected the two line wires to the new Aube (L1 and L2, L1 is black and L2 is red on new thermostat) and the the two load wires to the new aube and turned power back on, the display didn't come on. For more info, the switch box has 3 NM bundles coming in - L1 had two of the whites tied together from 2 NMs and L2 had two blacks tied together from the same 2 NMs. T1 was the white wire from the third bundle and T2 was the black wire from the third bundle. The old thermostat still works but is pretty inacurate. Any ideas what to try next?

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Old 03-10-07, 08:34 PM
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OK - I figured that one out - after getting a multimeter in this home (it's a vacation home), I figured out that the electrician had hooked up the loads and line inputs backwords. With an old style manual thermostat it doesn't matter if the lines are hooked to the loads and vice versa.

Now - I'm trying to figure out another thermostat that is hooked to two blower in floor electric heaters. The old thermostat works fine but when I hook the 4 wires up to the new thermostat in the same way as the old - no power to the stat. Since I've got the right four wires (the old thermostat works), I'm thinking that one of "load" wires is actually line. I'm having trouble using the multimeter since this hooks up to two separate breakers (two 20 amp breakers each). It looks like this box is wired differently than the other two I've tried with the white wires (neutrals) wired together like lighting circuits. Any ideas? thanks!
 
 

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