MEROSS connected radiator head test: an almost test for an almost good product ...

The Alexiens always try to find you new products, out of the ordinary, of good quality and / or with the extra thing… We have been following the brand for a while Meross with his catch et its multiple sockets and we have never been disappointed with the product quality of the Chinese brand.

Confident, we decided to test, in January 2019, the connected radiator thermostat Meross MTS100H. A product at 69,99 € only that we have not since included in our selection of the best connected thermostats for lack of having been able to carry out a convincing test of it at the time… But Meross having since rectified the situation, we will come back to it and present it to you again without really testing it since we have since opted for another model.

A radiator thermostat: what is it?

Let's start by seeing a bit of what it is… We are therefore faced with a thermostat for a water radiator. But, how do water heating systems work? There are different solutions knowing that the principle is always the same: to enter more or less hot water in the radiator to heat the room more or less.

  • The standard faucet: we will act on the quantity of water that will enter the radiator by more or less closing the tap, without being able to really act precisely and this, above all, will work continuously.
  • The thermostatic valve: there are several types but in general there is an incompressible fluid in the head of the valve which will expand according to the ambient temperature and come more or less to close, with a transmission rod, the water inlet in the valve. radiator via the valve body. You choose the target temperature with graduations or with an LCD display.
  • For connected heads: it is a bit the same thing with the presence of a liquid, a gas or a gel, in most cases, but with the expansion which will be done mechanically, according to the temperature recorded in the parameters and temperature given by the room sensor.

The MEROSS thermostatic head is battery operated for LCD display and Wi-Fi communication with the module takes place via the Meross MTS100 hub which requires two 1.5V AA batteries. It is this module, therefore necessary, which will make it possible to raise the temperature of the room and to control the heads of each radiator from the mobile application and by voice thanks to Alexa or Google Home.

MEROSS MTS100H: nice design… and… that's it

Le Meross connected thermostat comes in a very basic, brown cardboard box with the thermostat display. We find, in a foam, the thermostat, the module and a manual, in English only. This manual is quite simple and does not bring us much ...

We find there the MEROSS quality on the finishes and the quality of the plastic. However, the disappointments begin:

  • The 2 AA batteries required for the module are not included,
  • Le micro USB cable for the module is not included neither, nor the plug to connect it to the sector.
  • Edit 18.12.19: Meross added 3 Danfoss RA / RAV / RAVL connectors suitable for most installations.

In terms of operation, it is necessary to use the Meross application which has already proved its worth. We were therefore quite confident for the future, the brand having always pleasantly surprised us. But that was before proceeding with the installation and configuration!

MEROSS MTS100H: almost installation for an almost test!

The radiator thermostats are normally delivered with a specific valve body to come in place of your already installed fitting. So you have to get your hands dirty in most cases in order to change your equipment if you do not have a suitable valve body. It is not very simple even if possible: cut off the water supply to the radiator, turn off the boiler, bleed the radiator, dismantle the valve in place, put the one purchased, taking care to seal and put everything back into operation. .

If you had understood correctly how the thermostatic heads, you may have noticed a first problem ... Looking more closely, this Meross material is not a thermostatic valve but a thermostatic head. The difference ? The head will adapt to a valve already in place, whereas in general, thermostatic valves are supplied as a Kit with the valve body… Why? Because the heads are generally dedicated to one type of adapter, probe, etc.

So second problem: which thermostatic body and which adapter to put in place to go to the MEROSS? No information on the installation manual, nor on the brand's website, let alone on… Nothing at all… At the time of the test in any case, because Meross has since rectified the situation, we can only be congratulated.

Wanting to complete this test, yours truly went to different DIY stores showing them the thermostatic head Meross… Nothing to do, no one had been able to answer our questions at the time. Without additional information, it is therefore impossible to go further. The valve body adapter was not supplied with the device. Change the valve body? Yes, but without knowing the compatible models, in the absence of adequate documents, it was mission impossible and we were going in circles.

Since then, the Chinese company has revised its copy and specifies that a M30 X 1.5 connector or a Danfoss RA / RAV or RAVL adapter. It's clearer, isn't it? Yes, especially since Meross now supplies a copy of each. Too bad that we have, in the meantime, equipped ourselves with more expensive thermostatic heads following the Netatmo thermostat test that we even taught you to install in a installation tutorial on a gas boiler.

Why such a lack on the part of Meross? The answer seems to be the origin of the manufacturer. You have noticed that for the sockets, there are sometimes unpleasant surprises concerning the plugs that do not fit on our French wall sockets (the Alexians have already had problems directly with manufacturers). Certainly due to a lack of knowledge of the local market. And in this case, it seems to be. In the absence of a standard, the supplier has adapted to the main markets… Loupé… So we can only advise you to go for local brands in this type of installation like Netatmo, supplied in addition with adapters.

update 18.12.19/XNUMX/XNUMX - As you can see in the comments, Meross has visibly corrected the shot since our test! So much the better because, at this price, their solution is interesting. Currently marketed at € 39 each, these thermostatic heads therefore offer good value for money. Note that you will also need to invest in the Meross MTS100 hub which will be used to connect up to 16 of these heads. Thanks to our readers for bringing this to our attention.

MEROSS MTS100H connected radiator head:










Price quality



  • Nice design even if basic

The lessers

  • No information on valve body compatibility
  • Unable to install
Did i choose Alexa or did she choose me? Let's say that as a beta tester, it's a bit of both! And I do not regret having met our favorite assistant nor this adventure undertaken with Alexien Modo. Technophile, self-taught and loving popularization, I try to make our common passion easy to access!