Any electricians on here?

[Elite]

I recently bought a house and noticed there is 2 different sets of thermostat wires going to my furnace and a spare 3rd? Wondering if some one could explain what this is for? House only has 1 thermostat

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[oldillini]

Interesting read might offer some light ...

1 or 2 Transformers for Heating Cooling System Quality 101

1 or 2 Transformers for Heating Cooling System? I get this question a lot and I also see this question used in my stats on how people find

highperformancehvac.com

 

[StuckoYota99]

Well the pictures show 2 separate step down transformers. Most likely 120v to 24v.
Without seeing the inside of the furnace and where they are landed its hard to say why they are there.
I would recommend having an hvac tech look into it.

 

[Jstumbaugh]

Definitely two step down transformers. What kind of system are you controlling? Any indoor air quality system? UV, Humidifier, ect....

 

[ranchhand02]

People are usually shocked when they find out I am not an electrician.

 

[def90]

Generally electricians aren't the ones that pull TStat wire in a house and few of them know anything about how they work.

Second and extra wire could be for any number of things. Humidifier, air exchanger damper, zone dampers. You would have to remove the cover of the furnace and take a pic of where the wires are connected to know what is possibly going on.

 

[Boblee]

Generally electricians aren't the ones that pull TStat wire in a house and few of them know anything about how they work.

Second and extra wire could be for any number of things. Humidifier, air exchanger damper, zone dampers. You would have to remove the cover of the furnace and take a pic of where the wires are connected to know what is possibly going on.

Most if not all the electricians I work/worked with know how to pull and wire a thermostat , it's not difficult, there is a standard color/letter code for t stats.

 

[roadrunner]

Get advice from a licensed electrician instead of getting poor advice on a forum from mostly electrocuted hunters...

 

[packer58]

I have an electrical contractor buddy that also hunts...........so i guess you can be both.... but he does glow in the dark a little...

 

[oake]

Just a guess but it’s possible that the single wire going from one transformer could be for the doorbell

 

[Adrico]

The third picture shows a transformer powering a relay. Depending on where the wires coming out of the relay are connected to, (normally open, or normally closed contacts), that relay controls something that is activated either when the power coming in on that white wire goes off, or when the power is on.
The rest of the wires are possibly for other locations thermostats?

 

[Still Hunter]

Those are just two wire cables. Wires are just that, wires. You have two control transformers there. One is wired to a relay. Neither may even be wired to your HVAC. A typical T- stat has more conductors than just the two wires. One could be a Door bell transformer, one could be a relay to a heat sensor/ a smoke detector in your duct/ a float for your condensation lines, power to a security system etc., etc. You would really need to trace the wiring out to the devices they are attached to. Some systems have Heat Pumps/Exterior condensers' units/ Furnaces etc. Typical T-Stat Below ( has more than two conductors).

Marking	Wire Color Code	Description
R	Red	Power, 24 Vac transformer
Rc	Red	Power from cooling, 24 Vac transformer
Rh	Red	Power from heat, 24 Vac transformer
C	Black/Blue	Common of 24 Vac transformer
W	White	Primary heat cell relay
E	Brown	Emergency heat relay
Y	Yellow	Primary cool call relay
Y2	Yellow	Secondary cool call relay
G	Green	Fan relay
O	Orange	Change-over relay to cool relay
B	Blue	Change-over relay to heat relay

As long as the AC works, don't worry about it,