Electronic Thermostat STELPRO ET180 24 V | Montreal, Laval, Longueuil, South Shore and North Shore

In some Quebec homes, the wall thermostats do not control the baseboard heaters directly. They send a low-voltage signal to a relay, which then powers the heater. You can spot this setup by the thin wires at the thermostat instead of 240 V conductors. The Stelpro ET180 is a 24 V electronic thermostat made for these systems. At AirGreen, we use it to replace an old low-voltage thermostat that controls RE, RM or R841D1036 relays, with a two-wire installation and a digital display.

A low-voltage thermostat for relay systems

The ET180 runs on low voltage, with a capacity of 1 A at 24 VAC. It connects with two wires (R and W), which makes it a simple replacement in most existing setups. It is compatible with all RE, RM and R841D1036 relays, which in turn control the electric heating units.

On/off output, NO or NC

The thermostat works in on/off mode: it closes or opens the relay circuit based on the set point. The output can be set to normally open (NO) or normally closed (NC), depending on the relay type and the system logic. That flexibility makes it easier to replace an existing thermostat, whatever the original setup. Our technicians check what type of relay is in place before setting the output.

A battery-powered digital display

The ET180 has a digital display in degrees Celsius, powered by two AAA batteries, not included. The batteries run the display; the control circuit itself runs on 24 V. The display lets you read the temperature precisely, where an old dial thermostat only gave a rough idea. The set point adjusts from 5 to 35 °C (40 to 95 °F).

A compact, discreet housing

At 83.1 x 83.1 x 30.2 mm with an off-white finish, the ET180 takes up little room on the wall and blends in with most interiors. Its square shape usually covers the footprint of an old low-voltage thermostat well.

Why upgrade a relay thermostat

Original low-voltage thermostats are often mechanical and imprecise. They let the temperature drift by several degrees, so you end up setting the thermostat higher to make up for the dips. An electronic thermostat with a digital display lets you choose an exact set point and check it at a glance. In an electrically heated home, through a Quebec winter that lasts several months, better control of the set point in each room helps reduce energy use.

Replacing the thermostat is also a chance to have the relays themselves checked. An aging relay can stick or stop closing properly, which shows up as a room that heats nonstop or stays cold. During our visit, we test each relay controlled by the thermostat.

Finally, a digital thermostat makes everyday life simpler. Occupants see the actual room temperature, adjust the set point in precise steps and can tell right away if the heat is responding. For a building owner, matching thermostats that are easy to understand also mean fewer calls from tenants at the start of each winter.

Who it's for

The ET180 suits owners of a house or condo whose electric heating is controlled by relays, building owners who want the same thermostats throughout a building equipped with RE or RM relays, and anyone who wants a digital display without programming. It is not suited to a direct connection to a 240 V baseboard heater. In that case, a line-voltage electronic thermostat like the Stelpro ST302NP is the right choice.

How it compares to other 24 V thermostats

The D010 is a 24 V thermostat with a round dial, wired with three wires (R, W, C), no screen, and a range of 10 to 30 °C. The ET180 offers a digital display and a two-wire connection. The STE241 goes further, with a daily setback and ±0.5 °C accuracy. For a simple electric heating relay, the ET180 is the most direct solution.

Technical specifications

• Systems: electric heating units controlled by RE / RM (or R841D1036) relays
• Power supply: low-voltage, 1 A at 24 VAC
• Connection: 2 wires (R, W)
• Output: on/off, normally open (NO) or normally closed (NC)
• Compatibility: all RE, RM and R841D1036 relays
• Display: digital, in °C, powered by 2 AAA batteries (not included)
• Set point range: 5 to 35 °C (40 to 95 °F)
• Programming: non-programmable
• Dimensions: 83.1 x 83.1 x 30.2 mm (3.27 x 3.27 x 1.19 in)
• Colour: off-white

Placing the thermostat right

Like any thermostat, the ET180 measures the temperature where it is installed. If it sits near a window, an exterior door or an appliance, or in the airflow of a convector, it will read a temperature that does not reflect the room. When we replace one, we use the visit to assess the existing location. If the original thermostat is poorly placed, we can suggest moving it to an interior wall, at a suitable height, when the wire routing allows it.

Installation and maintenance

Our technicians shut off power to the transformer and the relay, identify the R and W wires, connect the ET180 and set the output to NO or NC to match the relay. They put in fresh AAA batteries, check the display and test the heat turning on and off. Replace the batteries as soon as the display starts to fade, ideally in the fall, before the heating season. Keep the baseboard heaters clear for an accurate temperature reading.

AirGreen is a family-owned HVAC company with an RBQ licence, active in Greater Montreal for more than 15 years, with a showroom in Boucherville. Contact us to buy the Stelpro ET180 thermostat and have it professionally installed in Montreal, Laval, Longueuil, the North Shore or the South Shore.

Stelpro documents

Stelpro spec sheet (PDF) · Stelpro user guide (PDF)