Electronic Thermostat STELPRO ST402NP 4000 W | Montreal, Laval, Longueuil, South Shore and North Shore

The Stelpro ST402NP is a non-programmable electronic thermostat rated at 4000 W for electric baseboard heaters and convectors. It's made for rooms with a high installed wattage, like a large living room, an open-concept area or a finished basement, and for homeowners who want to swap an old bimetallic thermostat for precise electronic control, with no programming and no app. Its standout feature is ECO mode, turned on with a single button, which lowers the temperature when you don't need full comfort. At AirGreen, we install it when the goal is precision and simplicity.

Precise electronic control for heavy loads

You feel the difference between an old mechanical thermostat and an electronic one right away. A mechanical thermostat lets the temperature swing by several degrees: the room gets too hot, then too cold. The ST402NP reads the temperature with a thermistor and holds it within ±0.5 °C (1 °F) of the set point. The result is a steady temperature and heating that doesn't needlessly overshoot the set point. According to Stelpro, this type of control can bring up to 12% in energy savings, based on an independent study.

ECO mode, at the touch of a button

The ST402NP has no schedule, but it offers an ECO mode that lowers the temperature in one move. At bedtime, when you leave for work or when you head out for the weekend, one press is all it takes; when you get back, another press brings back your comfort set point. Many people find this more natural than programming: you stay in control, with no menus.

Who it's for

This thermostat is mainly for people who want controls with nothing to learn: one screen, two arrows, one ECO button. It's also popular in rental units, where a simple device means fewer calls from tenants, and with seniors who would rather adjust the setting themselves than rely on a schedule. It also fits rooms with irregular use, like a basement family room or a rec room, where a fixed schedule would make little sense.

A 4000 W capacity

The thermostat runs on 120, 208 or 240 V. Its load range is 150 to 2000 W at 120 V, 260 to 3475 W at 208 V and 300 to 4000 W at 240 V. That capacity lets it control several baseboard heaters on the same circuit, a common setup in the large rooms of Quebec homes. For a room with a more modest wattage, the ST202NP, ST252NP and ST302NP models from the same family cover 2000, 2500 and 3000 W respectively.

Easy to read, easy to install

The digital display shows the temperature in °C or °F, your choice. The set point range is 5 to 30 °C (41 to 86 °F). Installation uses a 2-wire connection, and the S3 mounting plate makes mounting easy, solid and safe. The white moulded plastic casing blends in with most decors. The thermostat is certified to CSA C828-19, the standard that governs the performance of thermostats for electric heating.

Non-programmable or programmable

The ST402P is the programmable version of the same thermostat, with a schedule of 4 periods on weekdays and 2 on weekends. If your schedule is regular and you want temperature setbacks to happen on their own, the ST402P is the right fit. If you'd rather decide for yourself, when you want, the ST402NP and its ECO mode are simpler. For a fan heater, choose a model from the FF series instead, like the ST402NPFF.

Technical specifications

• Type: non-programmable electronic line-voltage thermostat
• Systems: electric baseboard heaters and convectors (2-wire)
• Voltage: 120/208/240 V
• Load range: 150 to 2000 W at 120 V; 260 to 3475 W at 208 V; 300 to 4000 W at 240 V (max. 4000 W at 240 V)
• Display: digital, °C or °F (selectable)
• Accuracy: ±0.5 °C (1 °F), thermistor sensing
• Set point: 5 to 30 °C (41 to 86 °F)
• Function: one-touch ECO mode (temperature setback)
• Connection: 2-wire; S3 mounting plate
• Savings: up to 12% according to Stelpro (independent study)
• Certification: CSA C828-19
• Colour: white, moulded plastic

Installation by AirGreen and tips for everyday use

Replacing a baseboard thermostat is electrical work on a 240 V circuit. Our qualified technicians shut off the circuit at the panel, confirm there's no voltage, then measure the total wattage of the baseboard heaters being controlled to make sure it falls within the ST402NP's range. They install the S3 plate, connect the two wires and secure the thermostat. Once the power is back on, they check that it works and that the display reads correctly.

If you're replacing several thermostats, we help you pick the right model for each room based on its installed wattage, so the whole house keeps a consistent look.

Saving through the winter

ECO mode is your main tool for saving. Turn it on at bedtime in your living spaces and when you leave the house for several hours. Don't crank the set point to the max to heat faster: a baseboard heater always heats at the same speed, whatever the set point. A steady temperature, turned down slightly at night, gives you the best balance between comfort and consumption.

Maintenance

Dust the thermostat and the baseboard heaters at the start of the heating season. Keep the space in front of the baseboards clear of furniture and curtains, so warm air can move freely and the thermostat reads a representative temperature.

Why AirGreen

AirGreen is a family-owned HVAC company that holds an RBQ licence, with more than 15 years of experience and a showroom in Boucherville. We modernize electric heating and install wall-mounted and central heat pumps that take some of the load off the baseboards. We can assess your home and suggest the combination that works best for you.

Contact AirGreen to buy the Stelpro ST402NP thermostat and have it professionally installed. We serve Montreal, Laval, Longueuil, the North Shore and the South Shore.

Stelpro documents

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