Thermostat wiring color code conventions Q&A

Page top photo: a typical round Honeywell T87 type wall thermostat base plate showing where the principal wires are connected.

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.

Photo just above: White Rodgers 1F56N-444 room thermostat discussed below.

Will an electronic thermostat still power the zone valve for my radiant heat system?

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 zone 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 2019-04-16 by Richard

Reply by (mod) - yes if you choose the right model thermostat - here's where to look

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.

You need a thermostat that provides a SPDT switch - that's Single Pole Double Throw. Such are common and available.

Look for a four wire compatible zone valve compatible thermostat like the White-Rodgers 1F56N-444 that I show above

and that we discuss in detail along with wiring instructions

at THERMOSTAT WIRING WHITE RODGERS

or a thermostat that has an O/B terminal to control zone valves that require voltage to close.

Some older mechanical thermostats will work with your zone valves as well as many newer electronic or digital thermostats.

Daniel F

What do I do at the thermostat if my apartment is always too hot?

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 2018-09-09 3 by Karen

Reply by (mod) -

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.

Step through the diagnostic and repair procedure

at HEAT WON'T TURN OFF

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

Why does my heat blow cold air and air conditioner blow hot air

What would cause my heat to blow cold air and and ac to blow hot air? On 2016-05-17 by Jeff

by (mod) - wiring error

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

Current Thermostat wire bundle colors are red, white, orange, green blue

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 On 2015-07-17 by Nick

by (mod) - thermostat wire color codes are unchanged

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.

...

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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