Élios COMM 24 V Smart Thermostat – ST1S42RW1
Élios’ Wi-Fi smart thermostat, wired as a communicating control or as a standard 24 V thermostat.
AirGreen codeAG-AC-060
514 316-2973 · sales@airgreen.ca
Quick facts
The Élios ST1S42RW1 smart thermostat is a programmable wall thermostat, powered at 24 V AC and connected to Wi-Fi. What sets it apart: it can be wired two ways. In communicating mode, its HA and HB terminals connect it directly to the Élios unit; in 24 V mode, it controls a conventional system through the usual terminals.
A thermostat for Élios ducted systems
Élios lists it as an accessory for its GGHLA wall-mounted air handlers, its GPHLA extra-slim fan coils, its EAHM air handlers and its GCHMA coils. It replaces the supplied controller with a thermostat that has a familiar look, with scheduling, app control and remote updates.
What it controls in 24 V
- 1- or 2-stage cooling or heat pump compressor (Y1, Y2).
- 1- or 2-stage heating or auxiliary heat (W1, W2) and emergency heat.
- Reversing valve (O/B), fan (G) and power (R/Rc, Rh, C).
Before installation
Depending on the type of unit, some functions are not available with this thermostat, the manufacturer notes. It is powered by the common wire (C); the manual provides a PEK+ terminal for a common wire extender. 18 to 24 AWG wires are stripped 0.3 to 0.4 in. It operates from 0 to 35 °C. Élios covers it with a standard 5-year warranty, subject to its terms.
Installed by AirGreen in Greater Montréal
We install and configure the ST1S42RW1 with your Élios system in Montréal, Laval, Longueuil, on the South Shore and the North Shore. RBQ licence 5645-9605-01. For availability or a quote, call us at 514 316-2973 or email sales@airgreen.ca with your indoor unit model and the quantity.
A real wall thermostat for your Élios system
The ST1S42RW1 talks directly to the Élios unit through the HA and HB terminals, or runs a conventional 24 V system.
- GGHLA wall-mount air handlers, GPHLA slim fan coils and EAHM air handlers
- Central-Elios GCHM coils added to a furnace
- Heat pump with auxiliary and emergency heat on 24 V (O/B, W1, W2)
- 24 V systems with 1 or 2 stages of heating and cooling
Specifications
From the manufacturer’s documentation. A value the manufacturer does not publish is not listed.
What to know before installing
- Depending on the unit type, some functions are not available through the ST1S42RW1, Élios notes.
- Strip wires 0.3 to 0.4 in; 18 to 24 AWG accepted.
- It operates from 0 to 35 °C: mount it indoors, away from heat sources.
- The thermostat is powered through the common (C) wire; the manual provides a PEK+ terminal for a common-wire extender.
- Smart thermostat
- Trim plate
- Mounting base
- Wire labels
- 2 screws and 2 anchors
- Manual
Manufacturer documents
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Frequently asked questions
What does “COMM” mean?
The thermostat can communicate with the Élios unit through the HA and HB terminals, without the usual 24 V wiring. It can also work as a conventional 24 V thermostat.
Is my Élios unit compatible?
Élios lists it in the submittals for GGHLA and EAHM air handlers, GPHLA units and GCHMA coils. Send us your indoor unit’s model number and we confirm before ordering.
Which app do I use?
The Élios ST1S42RW1 sheet lists Wi-Fi control through the manufacturer’s mobile app. We pair it with your network at installation.
Can you install it?
Yes. We mount the thermostat, pick the wiring mode, set the stages and backup heat, and join it to your Wi-Fi, everywhere in Greater Montréal.
The smart thermostat for your Élios system
Tell us the size and the quantity: we confirm availability and send you a quote. Or let our technicians install it for you.
Specifications from the manufacturer’s documentation, checked on October 7, 2026.