Question about Honeywell Programmable Thermostat Heater

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Thermostat installation I am installing a new thermostat for my baseboard electric heat. The electric box has 2 wires comming into it. So I have 2 black, 2 white and 2 ground. The old thermostat had a place for all 4 wires (one side line one side load) the new thermostat is a honeywell RLV430 High voltage (at least I got the high voltage part right). It only has 2 wires so I am at a loss as to what to hook up where.My inclination is to hook the load to one and the line to the other. But I don' know if this is right

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Re: thermostat installation

On paul 306, I don't have any info on you're system, but the old thermostat that has the smaller wires with the colors you described is a low voltage (24volt) controls. The new one you purchased sounds like it is for a system that is made for line voltage (120 volts or more) connecting this to the unit may have bad results. This also may apply to GUEST.
COACOOCHEE, the white and black coming into the box is the line, even though white should not be used for line, the connections for the other side of the thermostat is the load. The new thermostat you have be a single pole break as opposed to the old one may be a double pole. You should have a meter to check the voltage coming into the box, it may be 120 or 220 depending on what you have. Without any more info I cant be sure, but you may be able to connect the black wires to the switch and the white together. But it would be wise to test with a meter to be sure before doing this.

Posted on Dec 17, 2007

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Re: thermostat installation - Honeywell Programmable Thermostat Heater Thermostats

How do I install a basic digital thermostat?

Posted on Feb 04, 2008

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SOURCE: I am installing a new thermostat for my baseboard

Any thermostat for elecric heat breaks the line/load connection as you said. Your old thermostat broke both the hot and the neutral. I would recommend first that you consult the instructions with the new thermostat or go to their website at
to use their online help. Without seeing the instructions or the thermostat I think you are probably right. I would hook one black to one, the other black to the other, and the whites (which are neutral) together. Let me know if you need more help but check the website.


Thanks for using FixYa

Posted on Mar 04, 2010

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SOURCE: The middle of the touchscreen of my Honeywell

it not a touch screen, its manual old style honeywell, square box, not round, not rectanglur.

Posted on Nov 03, 2013

Testimonial: "It is a touchscreen. I have seen references to the battery being round and lithium CR2450; however, not sure if this is accurate. Does anyone know?"

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My existing thermostat is a Electromode for baseboard heater. The wires that are connected to the old unit are 2 black and 2 white wires. How do I go about connecting the new Honeywell??

U need to find out what those connections were for on the original thermostat and then rewire the new thermostat to conform.

Mar 14, 2016 | Thermostats

1 Answer

Fahrenheat md26r

This thermostat is a DPST (Double Pole Single Throw) type meaning it will switch BOTH pairs of wires either ON or OFF. It is a type used primarily for 220 - 240 volt circuits and can switch up to 22 amps of load current. Most heaters will provide a wattage rating and some also provide a current rating as well. Since most electric heat circuits are connected to a 2 pole 15 or 20 amp circuit breaker (or fuses) via #12 copper wires it should work well. If connected to a circuit greater than 20 amps - as long as the heaters connected to the circuit do not draw more than 22 amps will also work fine.

If all is well so far, the continue. The thermostat should have 4 wires. Two of one color, two of another (black and red are common colors). One color group will be the LINE (powered) side, and the other group is the LOAD (heater) side. You should verify WHICH color group is which for best results. The switch will open and close a connection between the LINE wires and the LOAD wires.

The thermostat should be installed in an electrical switch box located on an interior wall at about 5 feet high and not above any heater or heat source. Do not locate it behind a door that swings open, etc. The box should be supplied by a circuit from the electrical panel that will connect to the LINE side color group wires *and* a circuit that will extend from the thermostat's LOAD color group wires to the heater's wire connections / terminals.

If running common #12/2 (for a 20 amp circuit breaker) or #14/2 (for a 15 amp circuit breaker) romex cable from the panel will have the Black and White wires connected to the thermostat's LINE wires and the Black and White wires in the #12/2 or #14/2 romex cable from the heater will be connected to the thermostat's LOAD wires. The ground wires will connect to each other AND a short length of the same size wire should be run from this same point to each: the ground terminal screw of the thermostat and (if using a metal electrical box) to the electrical switch box with a separately purchased green ground screw designed specifically for this purpose. Plastic boxes are not grounded.

Leave a comment if you have other questions & good luck!

Dec 09, 2013 | Fahrenheat Thermostats

1 Answer

Can't figure out how to wire RobertShaw 4220 thermostat for heat pump and electric air handler

Do you have the wiring Diagram If not you can look online for them or go to the place you purchased it I would like to tell you the Color code But not all installers use a color code Properly.

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Above some of the baseboard electric heating vents (the whole house is wired with electric (not gas, oil, or coal) heat there are black marks on the walls. what is causing this??? I do not burn candles,...

While it could be nothing, it is a good idea to have a heating professional check them once in a while. Sounds a little odd, though, as most electric baseboard heaters have no vents. You will be comforted by the reassurance of having them looked at. Farmerbear at

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2 Answers

I am installing a new thermostat for my baseboard electric heat. The electric box has 2 wires comming into it. So I have 2 black, 2 white and 2 ground. The old thermostat had a place for all 4 wires (one...

One wire is "IN" the other is "OUT" A Thermostat works by "Breaking" the "Phase" line. It is just that simple. You usually have a pair of wires that connects, on the "Hot" side, to the always power ON line, & neutral. The Circuit, or Load, on the "Cold" side, has a a pair of contacts that open & close depending on Thermostat, in series with that conductor. Hot Contacts Cold P In-------------------><-----------------P Out

Mar 04, 2010 | Honeywell Programmable Thermostat Heater

1 Answer

Turned t stat off baseboard is still hot and has been for 2 days

Turn off the power to the baseboard at the breaker box. Remove the cover on the thermostat, check that there is no power going to it, remove the thermostat from the wall and bring it to yor local electrical supply house for a replacement. Most liokely the contacts are welded closed. Make a small diagram of the wiring or take a picture to be able to put the new one on without confusion.

Oct 18, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

Want to replace analog Honeywell thermostat with digital

Your system uses 24 volts and that thermostat should work. You should only have a two wire system and that should work using the RH and W connection on the thermostat. My personal opinion about that thermostat...I don't like it. It will timeout for 15 minutes after furnace does not fire up. I deal with this thermostat all the time because that is what they install in the new homes. I always have to pull it off the wall, remove the batteries and wait for it to completely drain power becuase it does not have a reset switch. Very irritating...Might be too complicated for your application.

Oct 17, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

Replace three wire thermostat with four wire thermostat

From the two red and two black wires (and the specs in the pdf), your new thermostat sounds like it's designed to directly control the line voltage (120 or 240) to the heater. That's the usual way baseboard heaters are controlled.

Could your wires be red, black, and (old, yellowed) white, the standard colors in a 3-wire power cable? Just the red and black should be enough to control a 120-volt heater so I don't understand what the white would have been used for. If it were my heater I'd take off the cover(s) -- with the power off, of course -- and find out what those wires actually connect to.

Jan 26, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

Installing CM900 Honeywell into Junior 24 Bosch Combi

What kind of boiler are using is this boiler a on the demand electric or gas? You need low voltage wires. If you get me make and model # of off boiler i can try and find wiring diagram . Tell me a little more about you heat system to. Like baseboard heat or in floor how many zones

Jan 16, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

I have no display and i checked the braker box

what is the thermostat running?(furnace,boiler or baseboard) if it is electric then you will have to install a new one.

Jan 08, 2009 | Honeywell Programmable Thermostat Heater

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