Baseboard Setback Thermostat installation

I've wanted to install programmable setback thermostats for my electric baseboard heaters for a long time.  This type of programmable setback thermostat has only become readily available in the last few years.  These thermostats are actually pretty easy to install, but they can be a bit pricey because you need so many; one for each room just about.  I've now installed three setback thermostats, one in the living room, another in the dining room, and the third in our kitchen.  In our home this is really just one big living space.  I now just purchased a fourth from a vendor on Ebay, and I intend to install this one in our bedroom.  I believe Ace Hardware is actually selling the same baseboard heater setback thermostat, model ELV1 from LUX at a very competitive price.  The thermostat is also known as model PSPLV510.  The bedroom setback thermostat will probably have a slightly different program than the other thermostats in the living area.

Testimonials

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Warning:

You must use this information at your own risk.  You are responsible for meeting your local building codes and the National Electrical codes.  On this web page I've simply documented my household project.  Make absolutely sure you turn off the correct 240 Volt circuit(s) at your breaker panel before you proceed with any electrical installation, and please, follow the instructions provided with your product.  This article truly only applies to a 240 Volt installation.  A 120 volt installation may require a true two pole thermostat which the ELV1 is not.

The National Electrical Code documents may be purchased through the National Fire Protection Association.  See codes NFPA 70 in the NEC Link above.

Electric baseboard thermostats are different from virtually all other thermostats

These setback thermostats operate at "line" voltage, the same voltage as all the appliances in your house.  Actually in most cases 240 Volts, the voltage your electric stove, dryer, or water heater typically run on.  This is a dangerous voltage and obviously a serious (deadly) shock hazard.  Most home thermostats operate at low voltage, 24 Volts, a much lower, safer voltage.  A typical home heating and ventilation unit will have an internal "power relay" that a low voltage thermostat controls using this low voltage, and therefore low power level.  This article is about high powered, high voltage thermostats used primarily for electric baseboard heaters.

Some comments about setback thermostat technology from the Dept. of Energy

Please see my article regarding heating our basement and floors!

The thermostats I'm replacing

You've all probably seen these basic thermostats.  They do have an "off" position which actually the programmable baseboard setback thermostats don't always seem to have.  If you have a vacation home this might be important to you if you want to completely shutdown and winterize your vacation home.  Frankly I think it's safer and potentially less costly just to set the thermostats at a safe low temperature to protect your home in the winter.  I must say though that if you do fully winterize your house you will be less likely to have "mice in your attic" (please see my trick to aid solving this) like we did at one point.

You can fully turn off the programmable ELV1 by unplugging it from its base plate.  The ELV1's are removable so you can sit in your easy chair and program them.  This is one way to achieve full shutdown if you still need it, but also want a programmable baseboard thermostat setup.  I didn't realize this thermostat had this feature (removability) until I had purchased it.

Baseboard thermostats and "poles"

My original thermostat would be known as a "two pole" unit, basically because it has a built in on/off switch as well as the thermostatically controlled switch.  Note: In my opinion this is not what "two pole" means but it is how this original thermostat is labeled.  In my house these two switches were set up to each turn off a "side" of the incoming 240 Volt circuit.

The LUX ELV1 is a "single pole" setback thermostat, but that's OK, because it can still be used to replace the "two pole" original.  Single pole in this case simply means the ELV1 only has the one thermostatic switch, which is completely sufficient to properly control your 240 Volt baseboard heaters.  If you have 120 Volt baseboard heating setup the ELV1 may be a "drop in" replacement; you wire it exactly as the original thermostat, but only if the original circuit and thermostat was "single" pole unit.  To the right is the Ace version of the LUX Elv1 Thermostat.  Ace is selling this unit at about $39.00 which is a reasonable price.  In 2003 this type of thermostat seemed easy to find but when I shopped in late 2004 I couldn't find them readily at my home centers.  Perhaps people just don't want to chance installing them, but at least Ace is carrying them, and sells them from their web site.

The existing thermostat wiring.

Again before you start make sure the circuit is off to this thermostat.  One way to do this is, assuming you know the heater worked, turn off the appropriate circuit breaker and turn the thermostat way up, then verify the baseboard heater simply remains cold.

This is the original thermostat removed from the wall.  The first thing to notice is the properly installed base copper ground wire.  One red and black wire pair on this thermostat was an on/off switch and the other red and black wire pair was the thermostatic switch.  The "circuit box" had two cables each with two wires and each also had a copper ground wire.  The copper ground wires are wrapped together, crimped, and a the wire is also tied to the metal case of the existing thermostat.  Since the new thermostat is all plastic this wire is unused in the new installation.  In my case the one incoming cable is the 240 Volt circuit.  The wires are called L1 and L2 which means Line 1 and Line 2.  A 240 Volt circuit has two 120 Volt "Lines".  The voltage "across" these two wires, or lines, is actually 240 Volts.  The electrical code states there shall be no voltage higher than 120 Volts in the typical household, but when you combine two circuits (properly) the "difference" is 240 Volts, but each line (L1 and L2) only has a 120 Volt potential when measured with respect to "ground"!  Ground in this case can be thought of as the bare copper wire.  This type of circuit (240 Volt) can carry more "power" with slightly smaller wires, saving money on wiring costs; copper is expensive.

If your wiring is aluminum I'd stop right now and hire a professional, don't even disconnect anything.  Aluminum wiring is difficult to work with and can be a fire hazard.

The other cable in the junction box goes to my electric baseboard heater elements.  How do I know this?

Here's some additional information about codes, and color coding at Wikipedia.  Electrical Wiring.

Which incoming cable is 240 Volts and which comes from the baseboard heaters?

I can use my volt/ohm meter to determine this.  With my volt/ohm meter in ohms mode, if I measure the resistance (ohms) between one of the incoming cable's two insulated wires, I'll read a very high value.  (Again the circuit must be OFF!)  This is the incoming 240 Volt circuit.  If I measure the other two insulated wires from the other cable I might read something like 40 ohms, this is the cable to the baseboard heating unit(s).

My new thermostats

To the right, the new ELV1 thermostat and below a shot of the base plate after wiring it in place.

You can see the ELV1 base plate only has two wires since it is a "single pole" device.  This base plate seems to house the actual relay or switch that will turn the baseboard heater(s) on and off.  Of course for this photo the ELV1 thermostat itself is removed from the base plate.

Preparing the wires

As you proceed with your installation you may note that there is some discoloration or oxidation that remains on the "stripped" or bare ends of the wires from the incoming cables.  It would be a good idea if you have excess wire length to cut off these ends and "re-strip" the ends so you have shiny un-oxidized wire for a good clean connection.  An alternative is to lightly sand the existing wire ends with a fine grit sandpaper until they are nice and shiny.

Wiring the ELV1 base plate

The old thermostat as mentioned above had two switches, on / off, and the thermostatic switch.  Each wire from a switch (red and black) was connected to one wire from each cable entering the box.

Note: if you have more than two cables entering your box you have some type of complicated wiring setup.  You may be able to figure it all out using your ohmmeter, but this article was written for the simple, and what should be typical, case.

To use the new "single pole" thermostat you must first connect one wire from each incoming cable directly to one wire of the other incoming cable.  In my case this is the upper wire nut in the photo above and I tied the two black wires together.  I could have tied the two red wires together instead.

The incoming wires should be a red and black pair or black and black pair for both cables.  If their is a white wire in your box, somebody didn't follow the electrical code, or you have some type of complex setup.  In my house I ran into both color schemes (black/black, red/black).  My home is modular so the two half's were probably built at different times and wired by different electricians.  I've actually noted differences in quality in the two half's of our house!

The two remaining wires, (red in my case) one from each incoming cable, are wired to the two wires from the ELV1.  If you want to be thorough, the wire from the cable that you found above that went to the circuit breaker should be wired to the "line" wire of the thermostat.  The wire from the cable that you determined went to the baseboard heating unit should be wired to the load wire of the thermostat.  You can see in my case I do have a black wire from the thermostat wired to a black wire from a cable, BUT, I also have a red wire from the thermostat wired to a BLACK wire of the other cable.  This is OK; both colors simply mean the wire is "HOT" or has high voltage on it.

With this wiring you have now created a loop with the thermostat and baseboard heater wired in series and then each end of this loop is tied to the 240 volt power source coming in on the one cable.

For this simple case it's hard to do it wrong

In this simple case, as long as a wire from one cable is not connected to a wire in the same cable, there really is no way to wire this circuit so that it will not function correctly using the ELV1 thermostat!  This may not be true of other thermostats! For this simple case make sure that each wire nut only has two wires connected together.

The bare "ground" wires

Again the bare "ground" wire is unused with the new installation and should be neatly dressed into the rear of the junction box.  The bare ground wires should remain twisted and connected together between the two incoming cables.  This is your safety ground circuit which must remain but does not have to be connected to the new plastic thermostat in any way.  The old thermostat was metal so a "ground" connection was mandatory for safety.

Other setback thermostats

It may be important for other baseboard thermostats to have one of the wires from the 240 Volt cable tied to the "line" side of the thermostat.  That's why it's good to go to the trouble to stick to the conventions so there is never an error, even if someone else were to rewire this circuit in the future.  Also other thermostats may need a ground wire connection!

Finishing up

With all the wires connected you can neatly insert them in the circuit box and mount your ELV 1 base plate to the wall.  Put some batteries in the thermostat, program it, and you're ready for a more comfortable home and hopefully some savings on your electric bill.

Testmonials

From:    Patti
To:       Bob
Cc:
Subject: Baseboard thermostats

Thanks, Bob! After reading your page on electric baseboard thermostats, and using your handy link to buy them at Ace, I've replaced all the crummy old thermostats in my house. I wouldn't have had a clue it could even be done without your site! You are an example of the Internet at its best -- people from all over sharing information and helping each other out. I've sent my little contribution -- worth all 150 pennies. Thanks again. Patti

11/12/2005 Thanks Patti !   Patti's right the internet is a great source of information, but please make sure you're confident it's accurate information, check several sources, and make sure you feel comfortable.

02/11/2007 My setback thermostat controllers are still working well.  In fact I haven't yet replaced any batteries!  I probably should just do them all on some period.  I've decided to leave the baseboard thermostats on Daylight Savings Time, since I and my cat seem to stay on EDT anyway.

I hope this helped with your baseboard setback thermostat installation.  I really love it now, the bedroom just cools down around bedtime and warms up automatically in the morning.

Thanks,
Bob