Thermostat STELPRO D010 24 V | Montreal, Laval, Longueuil, South Shore and North Shore

A dial you turn, clearly printed markings, no batteries and no menus: the Stelpro D010 is all about simplicity. This 24 V low-voltage thermostat with a round dial controls electric heating units through relays. It is designed in particular for SDHx and SDHR duct heaters, installed directly in the ducts of a warm-air or ventilation system. At AirGreen, we install it when the system calls for a three-wire 24 V thermostat, or when the client prefers a mechanical control that every occupant finds intuitive.

A dial thermostat for relay systems and duct heaters

Even though its trade name includes the word "electronic", the D010 is a dial thermostat with no screen. The dial has markings in °C and °F, and the set point adjusts from 10 to 30 °C (50 to 86 °F). You use it just like an old-style thermostat: turn it right for more heat, left for less.

Low voltage and three wires

The D010 runs on low voltage, with a capacity of 1 A at 24 VAC. It connects with three wires: R, W and C. The C (common) wire completes the 24 V circuit. That is an important difference from the ET180, which only needs two wires. So before a replacement, our technicians check that the existing cable really has three conductors, or plan to run a new one.

On/off control

The thermostat works in on/off mode at 24 VAC: it closes the circuit when the room is below the set point and opens it once the set point is reached. It is compatible with all RE, RM and R841D1036 relays, which in turn control the electric heating unit.

Duct heaters

A duct heater is an electric resistance element installed in an air duct. It is used, for example, to heat the air supplied to a zone, to supplement a central system or to preheat fresh air. This type of unit takes a low-voltage control signal and must not be connected to a line-voltage baseboard thermostat. The D010 is made for SDHx and SDHR models; for other heaters, we check compatibility with the relay and the unit's wiring diagram.

Simplicity, durability and everyday comfort

The D010's main strength is how easy it is to use. It suits seniors, shared spaces where occupants change often, utility rooms and rooms where a digital thermostat adds nothing. With no screen and no battery, it needs no special maintenance: no batteries to replace, no clock to reset after a power outage.

For saving energy, the rule is the same as with any non-programmable thermostat: pick a reasonable set point and keep it steady. During a Quebec winter, a room or zone heated by a duct heater runs for long periods. A set point one or two degrees lower, when the use of the space allows it, reduces the heater's running time. For zones that are rarely occupied, we can talk with you about the most suitable set point.

How it compares to other 24 V thermostats

The ET180 shares the same compatibility with RE, RM and R841D1036 relays, but it connects with two wires and has a battery-powered digital display, with a range of 5 to 35 °C. The D010 connects with three wires and stays fully dial-operated, with a range of 10 to 30 °C. The STE241, a 24 V electronic thermostat, adds a daily setback and ±0.5 °C accuracy. The D010 is the logical choice for an SDHx or SDHR duct heater, or when you want a 24 V thermostat with no screen.

Technical specifications

• Systems: electric heating units via RE / RM / R841D1036 relays; designed for SDHx and SDHR duct heaters
• Power supply: low-voltage, 1 A at 24 VAC
• Connection: 3 wires (R, W, C)
• Control: on/off at 24 VAC
• Compatibility: all RE, RM and R841D1036 relays; SDHx / SDHR duct heaters
• Display: round dial marked in °C and °F (no screen)
• Set point range: 10 to 30 °C (50 to 86 °F)
• Programming: non-programmable
• Dimensions: 89.9 x 89.9 x 39.9 mm (3.54 x 3.54 x 1.57 in)
• Colour: off-white

Installation by our technicians

Our technicians shut off power to the transformer and the heating unit, identify the R, W and C wires, then connect the D010. With a duct heater, they also check the relay, the heater's safety devices and the airflow in the duct, since the heater must only run with enough air moving through it. They finish by testing start and stop at different dial positions.

1. Shutting off power and identifying the wiring.
2. Connecting R, W, C and mounting the thermostat.
3. Checking the relay and the controlled unit.
4. Testing operation and adjusting the set point.

Placing the thermostat right

The D010 should be installed on an interior wall of the zone it serves, away from a supply vent, a window or a heat source. A thermostat in the stream of warm air from a grille would shut the heat off too early, while one on a cold exterior wall would keep it running too long. When we replace one, we assess the existing location and suggest moving it if it throws off the reading.

Maintenance

The thermostat itself just needs a wipe with a dry cloth. For duct heaters, maintenance is mostly about the air system: clean filters, clear grilles and a fan in good condition. Have the system inspected before the heating season.

AirGreen is a family-owned HVAC company with an RBQ licence, active in residential and commercial work for more than 15 years. Contact us to buy the Stelpro D010 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)