How to Wire a Thermostat to a Relay

The first thing you need to do is turn the power off to all the heating units.
Next, open up your thermostat and attach the back plate to the wall. Verify the wires and identify which are for heating and which are for cooling if that applies.
Luckily, ours have labels. If yours do not, you may need to use a toner.
The wiring we are using is 18 gauge with 5 conductors. For this demonstration, we'll say that it's a heat only set up, so there is only one wire.
You will want to peel back the wires you aren't using. In this case we will peel back yellow and green as a relay is a 3 wire system. The colors don't technically matter, but they are an easy way to remember.
Strip off about an 1/8th of an inch for each remaining wire.
You will notice on the thermostat, that there are a number of labeled ports. These are the same for all thermostats. (Show graphic)
You may not use all of them because they are for features your system may not have.

With this installation, we used blue as a common, it is common through out the system as it originates from the 24 volt transformer.

The R is the 24 volt transformers, power. We wire that to the R of the stat to provide "control" voltage & when used in conjunction with the "C" wire it provides power FOR the stat.

the W, is the call for heat, and is wired to the W of the furnace/heater/heat zoning panel or actuator valve depending on your system.

Then, push the wires back into the wall, and attach the thermostat to the plate.

Next, we will wire this thermostat to our switching relay.

We wired one thermostat, but for this example, we will wire two zones to this relay. This might be a thermostat on the first floor and a thermostat on the second floor. First, cut back your wires about a quarter of an inch.

The first thermostat, lets say from the second floor, will come in to the relay and connect to zone 2. We will only use the W wire for this thermostat since it will be stealing power from the furnace or boiler.

For the first floor thermostat we will use all three wires. First, connect the white wire to the W, the red wire to the R and the blue wire to the common. The R and the Common provide power to this thermostat from the switching relay.

Take care to make sure that you have a good connection under the screws, you can wrap the wire around if you want. Also, do not over-tighten as that can cause the wire to break.

Now, the relay will convert the 24v signal from the thermostat into a high voltage signal to activate a circulator pump, zone valve or actuator connected to the bottom portion of the relay.

If you want to learn how to wire a circulator pump to a relay, click here.

Видео How to Wire a Thermostat to a Relay канала SupplyHouse.com