Is there any reason why I cannot use a 4 wire thermostat (Honeywell T410B, DPST) to control two separate heaters (they are fairly close to each other)? The contacts are each(?) rated for 22 A and let's say hypothetically the heaters are going to draw 15 A each @ 240 VAC, so I cannot have both connected in the traditional sense. My plan is to have one heater on L1-T1 (thermostat contacts) and one heater on L2-T2 (N.O).

Below is the schematic of the typical system. Usually the L2-T2 contacts are used to break the neutral side of the heater (I'm assuming for extra safety). Since both the thermostat and N.O contacts operate simultaneously I can't see why this shouldn't be done. Both sets of contacts should be rated for 22 A since both will experience the same current when used in the traditional manner.

The real challenge is that I have one heater per wall receptacle (space heater) and I'd like both to turn off at the same time with one thermostat, rather than two separate thermostats.

I did contact Honeywell support, but I'm not confident in their responses.

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UPDATE: I believe Eugene Sh and Charles Cowie are correct. The second set of contacts is only controlled via a adjustment knob. Ensures that when you switch the knob to OFF it remains off, regardless of the room temperature.

  • \$\begingroup\$ Oh and I'd prefer to not use a relay. Sorry if that was not obvious. \$\endgroup\$ – Djames Apr 11 at 20:30
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    \$\begingroup\$ As far as I understand one pair is thermally controlled and the other one is a manual switch on/off. Is that your intention - have one thermally controlled and he other manually? \$\endgroup\$ – Eugene Sh. Apr 11 at 20:50
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    \$\begingroup\$ The instructions indicate that the second contact "breaks on positive off." That seems to mean that the heater connected to that contact will be on all the time and can be turned off only by turning the knob to zero. \$\endgroup\$ – Charles Cowie Apr 11 at 20:55
  • \$\begingroup\$ I understand now guys. You guys should work for Honeywell support because they could not explain this lol. \$\endgroup\$ – Djames Apr 12 at 12:43

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