How to wire a thermostat to a baseboard heater depends on the type being installed. This article will help with the wiring and connections.
You will simply connect the line and load of the wall thermostat to the wires in the box going to the heater. Make sure to shut the power off before doing this.
How To Wire A Thermostat To A Baseboard Heater For Line Voltage Single Pole
Most single pole line voltage thermostats should be mounted at a height of 60 inches on the wall. The thermostats usually go on an inside wall so they did not get draft.
As per the diagram provided you will see that the red and black wires come into the wall box in the back of the wall box to the heater.
To make this connection it is very similar as a standard single pole light switch.
You will connect the red wires through the box to the heater. This allows power to go directly to one side of the heater.
The two black wires remaining would go onto the thermostat.
One wire we go onto the load of the thermostat which goes to the heater and the other wire goes to the line of the thermostat which comes from the power source.
Turn dial thermostats are not important to get the line and load correct however it is important for the digital thermostat.
You should make sure you have a meter to test the power or has the wire clearly mark that comes from the power source.
How To Wire A Thermostat To A Baseboard Heater For Line Voltage Double Pole
To wire a double thermostat is very simple. They are almost like single pole thermostats. Both sets of wires will be broken inside of the wall box.
So you clearly have a line from the power source and clearly have a load going to the heater.
The red and black wires on the line side of the thermostat will get hooked to the line side wires coming from the panel, simply match the colors. The line side wires on the thermostat will be matched up with the load side wires going to the heater matching the colors also red and black.
This gives a full line break when the thermostat is shut off and there will be zero voltage to meter.
How To Wire A Thermostat To A Baseboard Heater For Low Voltage
Low voltage thermostats are used in instances where the rooms are too large to supply one circuit of electric baseboard heat.
This usually entails two circuits or more of electric baseboard heat for larger rooms.
Instead of having multiple thermostats control the same room you can control the same room with one low voltage thermostat.
We will write more on relays in another article. You should know for the purposes of this article that the low voltage thermostat controls the relays.
Much like a switch in your car to control your headlights. A low voltage thermostat does the same thing.
The low-voltage thermostat comes in a variety of selections.
You can use a simple two wire thermostat with batteries or a fancy Wi-Fi thermostat.
Most of these models have only two wires. The two wires which are low voltage then go back and turn the relays on.
What Are The Differences between The 3 Types?
When talking in terms of how to wire a thermostat to a baseboard heater.
The differences between actual thermostat parts come down to control and pricing.
You can get a simple turn dial single pole thermostat for around 20 bucks.
You can also control the same heating load with the fancy white I have Wi-Fi thermostat that cost hundreds of dollars.
The same applies for the low voltage thermostat which cost between $30 and $500 depending on how fancy you would like them to be.
Can I Have Power At The Heater Instead Of The Thermostat?
When it comes how to wire a thermostat in a baseboard heater, yes you can have power at the heater.
It is simply called what we referred to as a switch leg.
When the power comes directly into the heater from the power source or the panel in this case.
One side of the power source will go directly to the heater.
The other side of the power source will go up to the thermostat.
Other side of the thermostat will come back down to the heater.
When you break the line of the thermostat. Shut it on and off and break the line of the year this is actually a big loop.
Please refer to the diagram below. This can get a little tricky if you have more than one heater with the power to it so it’s always better to run power to the thermostat first.
How To Wire A Thermostat (In) A Baseboard Heater?
If you are looking to wire a thermostat directly in the heater then the diagram below will help you.
The power feed will go right to the heater. The one side of the 240 volt will get attached directly to the wire in the heater.
The other side (black wire) will go to one side of the built in thermostat.
The other side of the thermostat kit will go to the wire on the heater.
This method is commonly used to save money for fishing wires into walls to have a wall stat.
It does make the installation of the heater easier as you can usually run the wire right up from below or bottom of the floor.
You can find out more on baseboard heater wiring here.
How Do I Know Which Thermostat To Buy?
Knowing which type of thermostats to buy can be a little tricky…. Make sure when you take the old thermostat off that you shut the power off first.
Try to match the part numbers up so you can find something that will work.
If you have a digital thermostat and you would like to know more on what we recommend you can find that out here.
One of the most important things when making a purchase of the thermostat it’s a make sure you have the correct amount of wires.
Some thermostats will have more wires than what you need.
Consult your local electrician.
What Happens If I Wire The Thermostat Wrong?
If a thermostat is wired wrong several things can happen as an outcome. The first thing that can happen is a direct short in the circuit.
This will cause the breaker to trip or the fuse to blow.
The second issue that could happen it the heater comes on and won’t turn off. This is usually due to the connections being done wrong inside the wall box. It can usually be fixed by changing a simple connection.
Finally the heater may just not work at all. This is also caused by a connection issue.
What Is The Difference Between A Single Pole And A Double Pole?
The difference between a single pole and a double pole thermostat is this.
A single pole thermostat will only go down to 5 to 7°C. So when you turn it off it is not completely off. This is offered as a frost protection.
If you wish to shut the heater completely off then you will need to turn the breaker off .
A double pole thermostat is a complete line break of both sides of the 240 V circuit. This means when is actually off.
Some people don’t like this method for obvious reasons. If you shut it completely off then there’s a chance the pipes freezing.
How Many Heaters Can I Hook Up To This Thermostat?
Most thermostats have a rating right on the package of how many watts they will handle of electricity.
Most thermostats are also rated for 4000 watts. As a rule of thumb you cannot exceed 3840 W or 16 A on a standard 20 amp 240 V electrical circuit.
This is sufficient for the thermostat to supply. This means you can hook up a number heaters. From 300 watt on word up through to 2500 Watt.
You can wire your installation larger. However you will need a relay system with a low-voltage thermostat to control up the multiple circuits of 3840 W.
Can I Install A Smart Thermostat?
You can control heating load with a smart Wi-Fi thermostat.
This can be relatively expensive in the few hundred dollar range. For more on those you can see here.
Be careful on the type of thermostat that you purchase as it can slow down your Wi-Fi signal considerably.
Wi-Fi thermostats are great because you can control the heating mode of your home from away or from anywhere.
The bottom line is this you should always consult with your local licensed electrician if you feel like you’re in over your head.
They should be more than willing to off the advice to you as we never recommend to do your own electrical work.
The images in the post were used as we are certified Stelpro and Eaton installers.
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