Expert old thermostat wiring diagram - Word: a preceding installer may additionally have used a different set of coloration wires. This could be a non problem to hold tune of if an entire new set of thermostat wires is pulled. In any other case tag the wires before getting rid of from the existing thermostat, or be aware of the terminals each wire is connected to. If you have smooth access to the prevailing thermostat wires, simply cast off and follow the same direction with the brand new set of wires. You could use cable ties, electric tape, or staples (securing wires and cables article). Make certain to take a completely conservative size on how long your new set of wires should be. You don’t want to start over, if you arise short. Going into your furnace may additionally sound intimidating, but if you have the fundamental knowledge of wiring, and know the way to get rid of the proper furnace panels to access the electronics, you then should be best. The com 24v terminal could be related to the c (24 vac common) of the thermostat. A few programmable thermostats (e.G. Honeywell status wiring necessities) need a minimum of 5 wires, and maybe greater relying on what features you need to function (humidifier, etc). The extra 5th twine may be for common; offering stepped down power from a transformer.
In a scenario wherein the authentic thermostat wires may additionally have been stapled to an indoors wall stud, and no longer run thru conduit, you may be higher off leaving the present set of wires, and cutting them off on the entry and exit factors of the wall. Then feed new wires with a fish tape (klein gear). Check your local home development stores, or nearby device apartment, for apartment availability. A: in case you plan to upgrade to a new thermostat ensure you've got the right variety of wires to be had, otherwise your new thermostat received’t paintings (most advanced honeywell thermostats require a not unusual (c) wire to power on). In case you do need extra wires, you will want to don't forget how hard installing new wires may be to your software, and in case you need to budget for an electrician or hvac tech to put in the proper wiring.