I am replacing old line voltage thermostats and want to use Honeywell digital programmable units.

My current configuration is 2 wire but new thermostats are 4 wire. This is a 240V system with multiple heaters in parallel.

Can I use the new thermostats and how do I wire them if I can use them?

Thanks,

JR

Model numbers?

Quote:

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Originally Posted by hvac1000

Model numbers?

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Honeywell Digital LineVoltPro™ 8000 TL8230A1003

The spec sheet says it is a 4 wire stat

Does the thermostat box have 2 pair of wires in it, one from the breaker box, and one to the heaters? If so, easy enough. If 2 of the terminals are marked line, connect the pair from the breaker to the line terminals, and the pair to the heaters to the load terminals.

If you only have 2 wires, connect one to the line, and the other to the matching load terminal. I am not sure that meets current codes, but may be allowed as a retrofit. It will be just as safe as the old one was. The 4 wire system is safer, and I hope somebody is able to clarify the code issue.