Electronic Thermostat STELPRO ST252NP 2500 W | Montreal, Laval, Longueuil, South Shore and North Shore

Choosing a baseboard thermostat starts with choosing the right capacity. A thermostat that's too small for the connected load is non-compliant and wears out early; one that's far too big adds nothing. The Stelpro ST252NP fills a useful spot in the lineup: with 2500 W at 240 V, it suits rooms whose load goes over 2000 W without reaching 3000 W, a common situation in master bedrooms, offices and medium-sized rooms. It's a non-programmable electronic thermostat for electric baseboard heaters and convectors, with a one-touch ECO mode. At AirGreen, we choose it when the measured load calls for it.

The in-between capacity in the Stelpro lineup

The ST252NP runs on 120, 208 or 240 V. Its load range is 150 to 1250 W at 120 V, 260 to 2160 W at 208 V and 300 to 2500 W at 240 V. In practical terms, it can control a 2000 W baseboard heater plus a small extra baseboard, or a single longer baseboard, with a reasonable margin. On our visits, we often see rooms where an old 2000 W thermostat was controlling a load slightly above its capacity; the ST252NP fixes that without moving up to a bigger model than needed.

ECO mode

ECO mode lowers the temperature with a single button. It's designed for times when you don't need full comfort: at night, during work hours, when you head out for the weekend. A second press brings back your usual set point. For many people, this simple move is easier to adopt than programming. According to Stelpro, this thermostat's electronic control can bring up to 12% in energy savings, based on an independent study.

Fine control

The temperature is measured by a thermistor and held within ±0.5 °C (1 °F), over a set point range of 5 to 30 °C (41 to 86 °F). The digital display can be set to °C or °F. No more of the temperature swings typical of old bimetallic-strip thermostats: the room stays right where you set it, to the degree.

Mounting on the S3 plate

It connects with 2 wires, and Stelpro's S3 mounting plate makes for an easy, solid and safe installation. The white moulded plastic casing matches the other models in the lineup, so the whole house keeps a consistent look even when capacities vary from room to room. The thermostat is certified to CSA C828-19.

Which rooms

The ST252NP most often ends up in master bedrooms, home offices, medium-sized kitchens and rooms where the baseboard was replaced with a longer model during a renovation. It also suits corner rooms with two exterior walls, where a bit more wattage was sometimes installed than in the other rooms. In all these cases, it brings precise control and a simple ECO mode, with no programming to learn.

Its neighbours in the lineup

The ST252NP shares its features with the ST302NP (3000 W) and the ST402NP (4000 W). The ST202NP (2000 W), for its part, focuses on a freeze warning and a safety mode instead. For a fan unit, go with the ST252NPFF, designed for fan heaters. The right model depends only on the load and the type of unit; we check that for you.

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 1250 W at 120 V; 260 to 2160 W at 208 V; 300 to 2500 W at 240 V (max. 2500 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

Professional installation and everyday use

The first step is measuring: our qualified technicians note the wattage marked on each baseboard heater connected to the thermostat and confirm that the total falls between 300 and 2500 W at 240 V. The circuit is then shut off at the panel, the absence of voltage is confirmed, the S3 plate is mounted and the thermostat is connected. Once the power is back on, we test that it works, set the display unit and show you ECO mode.

For a full replacement, we draw up a list of rooms with their load and the matching Stelpro model. This method avoids capacity mistakes and ensures a compliant installation in every room.

Good winter habits

ECO mode is this thermostat's best ally. Get in the habit of turning it on at bedtime and when you leave, and turning it off when you get back. Avoid turning the set point all the way up to warm the room faster: the baseboard heats at the same speed, and the room may simply overshoot the temperature you want. Keep the doors of unused rooms closed and their thermostats in ECO mode.

Maintenance

Dusting the thermostat and the baseboard heaters at the start of fall is all it takes. Leave some free space in front of the baseboards for good air circulation. If you replace a baseboard heater with a higher-capacity model during renovations, have the thermostat's capacity checked before putting the circuit back into service.

Why AirGreen

A family-owned HVAC company that holds an RBQ licence, AirGreen has more than 15 years of experience in heating and air conditioning and welcomes customers at its showroom in Boucherville. To buy the Stelpro ST252NP thermostat and have it professionally installed, contact us. We serve Montreal, Laval, Longueuil, the North Shore and the South Shore.

Stelpro documents

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