Meross Matter Thermostat Review: Check Your Wiring First
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The Meross MTS300 has kept my Apple Home schedule running since January 2026 without a dropout,. Fit decides everything: without a C-wire, or with baseboard, millivolt, or two-wire heating, it won't run, so confirm what's in your wall before ordering.
Jump to where to buy →What works
- Six months running the HVAC schedule with no dropout or re-pairing
- The trim plate covered the old thermostat's footprint, so no patching or paint
- Matter hardware, so it can be shared into other ecosystems
- Install took about twenty minutes including removing the old unit
What doesn't
- A C-wire is mandatory, and older installs often do not have one
- The deeper scheduling lives in the Meross app, not in Apple Home
- Baseboard, millivolt and two-wire heating systems are not supported
The Meross Matter thermostat has been running my HVAC since January 2026 and I have no real complaints about it. Whether you’ll be able to say the same comes down to what’s behind your existing thermostat.
The compatibility problem, first
Meross says this thermostat suits about 95% of HVAC systems, heat pumps, air conditioners, furnaces, boilers, dehumidifiers, humidifiers. That’s true and it’s a lot of coverage. The part that sends units back is the other side of the sentence:
It requires a C-wire, and it is not compatible with:
- 110V / 120V / 240V electric baseboard heaters
- Millivolt systems (many older gas fireplaces and wall heaters)
- Two-wire systems
The C-wire, the “common” wire, is what continuously powers a smart thermostat. Older installations frequently don’t have one run to the thermostat location.
So before you buy anything: kill the power at the breaker, pull your current thermostat off its plate, and photograph the terminals. You’re looking for a wire in the terminal marked C. If there isn’t one, your options are running a new wire, fitting an add-a-wire adapter, or choosing a battery-powered thermostat instead.
Here’s the back plate of the Honeywell unit I replaced, before I disconnected anything:
A blue wire is sitting on C. Note what’s printed on the plate itself, just to the right of the terminals: C IS OPTIONAL WITH BATTERIES. That line explains why so many houses fail this check. Older thermostats could run on batteries and ignore the common wire entirely, so plenty of installers either never pulled one or left it tucked unused in the wall. A smart thermostat has no such option, because it needs continuous power.
The install
About twenty minutes, start to finish, including taking the old thermostat off the wall.
The single thing that makes a thermostat swap easy is labeling. The photo above is the old Honeywell plate before I touched it, and that photo is itself half the technique. As each wire came off I tagged it with the terminal letter it had been sitting in, so wiring the Meross up afterwards was a matter of matching letters rather than working out what a previous installer had intended. Thermostat wire bundles are color-coded by convention rather than by rule, and the convention gets ignored often enough that the colors alone aren’t safe to trust. Take a photo of the old terminal block before you disconnect anything, then label as you go.
Kill the power at the breaker first. The wires are low voltage, but the equipment they control isn’t.
The trim plate
The thermostat ships with a trim plate, sometimes called a wall plate, and it does more work than the spec sheet suggests.
Pull an old thermostat off a wall and you’re usually left with a rectangle of unfaded paint, two or more screw holes, and often a ragged opening where the wire bundle comes through. Every one of those has to be patched, sanded and touched up unless whatever replaces it happens to be bigger.
The Meross plate is wider and taller than the thermostat body, so it covered all of it. That meant no filler, no sanding and no trip to match a paint color mixed years ago. The old thermostat’s footprint is hidden completely and the edges sit flush against the wall.
Check for one on any thermostat you’re considering.
It is a Matter device that does not look like one
Nothing on the hardware says Matter. There is a Wi-Fi glyph in the top left corner and no Matter logo anywhere on the unit, and the name it arrives with in Apple Home is “Smart Wi-Fi Thermostat.” That name is just the factory default, which you can change in a second and which I never bothered to change.
The accessory’s own data identifies it as Matter, and because it is, it can be shared into other ecosystems alongside Apple Home rather than being locked to one app.
Living with it
It holds a setpoint and reports state accurately in Apple Home, currently showing “Cooling to 68°” as I write this, which is exactly what the schedule asked for. Setpoint changes from the Home app take effect promptly, and I haven’t had it drop off and need re-pairing.
The Apple Home integration gives you what you’d expect: current temperature, mode, target temperature, and inclusion in automations and scenes. If you want the deeper scheduling, that lives in the Meross app, the same split as their other accessories, where the core control is standard and the extras are vendor-side.
Hands-on notes
Purchased January 17, 2026 (White, US version) and installed on my own HVAC, which has a C-wire. It has been the thermostat for the house since, roughly six months at the time of writing.
Apple Home files it in the Living Room, reporting model MTS300 on firmware 9.3.2 with a Matter vendor ID of 4933 and product ID 57345. No re-pairing has been necessary since setup.
Who should skip it
- Anyone without a C-wire who isn’t prepared to add one or fit an adapter.
- Anyone with a system on the incompatibility list above; no configuration will change that.
- Anyone wanting a battery-powered thermostat with no rewiring at all.
Verdict
A solid Matter thermostat that has been dependable for six months. If you have a C-wire and a conventional HVAC system, buy it. If you don’t know whether you have a C-wire, go find out.
Where to buy, tested picks
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Common questions
Does the Meross thermostat need a C-wire?
Yes, a C-wire is mandatory. Line-voltage baseboard heaters, millivolt fireplaces and wall heaters, and setups with only two conductors are also out. Pull the cover off your current thermostat and see whether anything is attached at C before you spend the money.
Is the Meross MTS300 a Matter thermostat?
Yes. Nothing on the casing says so, but the accessory's own data registers it as Matter hardware, so it can join more than one ecosystem at once.
Runs the homekit.reviews test home, a real mixed Matter/Thread/HomeKit house. Everything reviewed here was set up, paired, and lived with. See how I test →