Thermostat wiring color code conventions Q&A

This article series describes the standard wire color conventions for HVAC thermostats and gives several tricks of the trade to get your theromstat wired correctly. .

Thermostat Wiring Color Conventions & Tips FAQs

These FAQs about thermostat wiring color codes or conventions & wiring tips were posted originally

at THERMOSTAT WIRING TIPS & COLOR CODES - be sure you check out the advice given there.

On 2019-04-16 by (mod) - will an electronic thermostat still power the zone valve?

Richard

I'm a bit nervous about a thumbs-up or down without knowing more such as how your zone valves are already wired.

Take a look at ZONE VALVE MANUALS & WIRING INDEX

Then see see THERMOSTAT WIRE CONNECTIONS

detailed room thermostat installation & wiring guide for each heating or cooling system type and each thermostat wiring specification

I would buy a replacement TT that indeed provides the connections for all 3 of the wires your present TTs use. Yes such are common and available.

On 2019-04-16 by Richard

Hi, I've got radiant hot water boiler heat in my house where there is a 3 wire (RBW) thermostat that works a separate heating valve on 3 floors.

So 3 thermostats work 3 vavles. R and W turn the heat valve on as in open it, when the thermostat is satisfied R and B close to close the valve and shut the heat off.

So my question is can I replace on of those thermostats with an electronic one? Would any of them provide power to B to shut the heating valve off? thx.

On 2019-03-31 by (mod) - wiring a Lennox unit

Austin you might want to check the ARTICLE INDEX to find live links to

Or see THERMOSTAT WIRE CONNECTIONS detailed room thermostat installation & wiring guide for each heating or cooling system type and each thermostat wiring specification

Or see THERMOSTAT WIRING DIAGRAMS - wiring diagrams for various thermostats

Or see THERMOSTAT WIRE FUNCTIONS - what each wire does

On 2019-03-30 by Austin Weber

I have a Lennox unit

The connectors labeled

X3 -y1-3- f/g- y/w1-w2-vr

There is a bridged wire from /w1 and f/g

My old mercury thermostat had

W1-W2-G-RC/RH-Y2 connected

My new thermostat has

B-O-G-Y-W-not used-R-RC

The heater used to get to temp and shut off now it just runs all the time

Heat turns on and off but the fan never stops until manually shut off

Trying to get it working and ac working again

On 2019-01-11 by Brett Fisher - 5-wire thermostat hookup

On a 5 wire thermastat are there wires on the furnace that will need to be put together.

On 2018-09-09 by (mod) - apartment is always too hot

Unless it has been damaged or mis-wired, when the thermostat is set below the room temperature it will not call for heat.

If the heat never turns off even with the thermostat set all the way down I'd try disconnecting its wires - first at the thermostat end, next at the heater end.

Perhaps you can post a photo or so (one per comment) so we know the brand and model and then we can comment further.

On 2018-09-09 3 by Karen

My niece lives in an apartment building with baseboard heating. It has old style thermostat with mercury bulb. The apartment is always hot.

When you turn the thermostat down the bulb moves and makes contact to call for more heat. It is a two wire connection, the only terminals are r and y. Any idea how to stop the heat?

On 2018-01-16 by (mod) - red yellow green hookup to red white yellow ?

John

We can't know from your text just how your system was wired, but t he article above on this page gives the sta ndard color codes

On 2018-01-15 by John

I have a three wire thermostat red, yellow, green. My new unit has spots for red, white, and yellow. How do I wire?

On 2017-09-15 by Rc

I have a robertshaw digital programmable thermostat n a round honeywell thermostat. Im changing out the honeywell qith the robertshaw but its a newer gas furnace abd i only have 4 wires( red, blue, green, and white) i hooked the red up to the R, the blue up to the B, grren up to G and white up to E/W1.. There is also a W2. Inside there is (in order from left to right) C, BLANK, R, O, B, G, Y1, E/W1, W1, BLANK, L. Did i wire up this thermostat correctly?

On 2016-12-02 by Tom

my furnace was just checked yesterday and i got heat but today i get cold air is it possible my Thermostat is dying and not relaying the correct info to the furnace?

On 2016-05-22 by (mod) - heat blows cold air AC blows hot air

Jeff. A heat pump that is not working or a control board that is mis-wired

On 2016-05-17 by Jeff

What would cause my heat to blow cold air and and ac to blow hot air

On 2015-07-17 by (mod) -

Thank you Nick. The thermostat wire color code usages remain the same. Some standard TT wire bundles include the addition of orange for use with heat pump systems. If you have different opinion or suggestion about the color assignments let us know.

On 2015-07-17 by Nick

Lately the company that makes thermostat wire changed the colours around, so older homes have the colours above, but if you bought a spool of thermostat wire lately, its going to be red, white, orange, green, blue are the new colours

...

Continue reading at THERMOSTAT WIRING COLOR CODES - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• THERMOSTAT INSTALLATION STEPS
• THERMOSTAT WIRE CONNECTIONS detailed room thermostat installation & wiring guide for each heating or cooling system type and each thermostat wiring specification
• THERMOSTAT WIRING DIAGRAMS - wiring diagrams for various thermostats
• THERMOSTAT WIRE TERMINAL ID CODES / FUNCTIONS - what each wire does

Suggested citation for this web page

THERMOSTAT WIRING TIPS & COLOR CODES FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HVAC THERMOSTATS

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