3M Filtrete WiFi Thermostat 3M-50

Aron Schatz
December 23, 2010
Provided By
3M Filtrete WiFi Thermostat 3M-50
The 3M-50 with the Marvell WiFi chip is a great step in the smart home direction. Now just give us the ability to control it directly and we're sold.

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We live in a world where everything is wired (actually, wireless). One of the latest pieces to go online is your home thermostat. Marvell produces WiFi radios for use in certain 3M Filtrete thermostats and the promise of being able to remotely control your own thermostat is a tempting offer. Think about going on vacation or a short trip and forgetting to turn down the heating. This isn't a problem anymore with the WiFi thermostat. In fact, you could warm up your house on the trip back.

About Marvell


A Next Generation Semiconductor Company

Founded in 1995, Marvell Technology Group Ltd. has operations worldwide and approximately 5,000 employees. Marvell's U.S. operating subsidiary is based in Santa Clara, California and Marvell has international design centers located in the U.S., Europe, Israel, Singapore and China. A leading fabless semiconductor company, Marvell ships over one billion chips a year. Marvell's expertise in microprocessor architecture and digital signal processing, drives multiple platforms including high volume storage solutions, mobile and wireless, networking, consumer and green products. World class engineering and mixed-signal design expertise helps Marvell deliver critical building blocks to its customers, giving them the competitive edge to succeed in today's dynamic market.




This is the packaging you'll see if you buy this at a retail store like Home Depot. The Filtrete product line has a few different models. Make sure you pick up the correct one. The model is 3M-50.


The back of the hard-to-open shell contains some extra information and the Marvell WiFi controller. It snaps into one of the expansion ports in the back of the thermostat.
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    * Assembled Depth (in.) : 1.7 in
    * Assembled Height (in.) : 4.5 in
    * Assembled Width (in.) : 5.9 in
    * Automatic Heating/Cooling Changeover : N
    * Backlit : Yes
    * Batteries Included : No
    * Battery Back-Up : Yes
    * Battery Operated : Yes
    * Battery Type : AA-Alkaline
    * CSA Listed : No
    * Color Family : Whites
    * Daylight Savings Time Ready : No
    * Display height (in.) : 1.5
    * Display width (in.) : 2.9
    * ETL Listed : No
    * Energy Star Compliant : No
    * Item Package Type : Plastic Container
    * Item Weight : .48 lb
    * Lockable : Yes
    * Low Battery Indicator : Yes
    * Manufacturer Warranty : 5 year Limited Home Depot warranty
    * Number of HVAC Zones : 1
    * Periods per Programmable Day : 4
    * Product Depth (in.) : 1.7
    * Product Height (ft.) : 4.5
    * Product Width (in.) : 5.9 in
    * Removable Interface : No
    * Shape : Rectangle
    * Thermostat Type : Heating and Cooling
    * Touch Screen Programming : Yes
    * UL Listed : N-No UL Code Rating
    * Vacation Mode : Yes
    * Voltage Rating : 1 millivolt to 24 volts
    * Wi-Fi Capability : Yes

Package Contents


The Filtrete 3M50 is packaged with the thermostat, the Marvell WiFi module, wire indication stickers, some literature, and a wire management sticker for the top of the thermostat.



The 3M-50 thermostat is a generic looking touch screen programmable model. It is about the standard size of the newer rectangular types. The sticker on the LCD looks nice, but the backlighting doesn't have any gradient to it. It is a good representation of the LCD as a mock up, though. The front of the 3M-50 has a few hard buttons. To the top left is a save energy button. To the bottom right are buttons for the menu and programming functions. There are status LEDs in the left and the WiFi logo on the top right.


There are two more hard buttons on the side of the 3M-50. There is a fan control button and a mode button for switching the HVAC unit from heating, cooling, auto, or off. Regardless of the hard buttons, the 3M-50 is totally electronic for the controls. There is no hard switch and it can change any option on the fly. Most programmable thermostats have a hard switch for heating and cooling modes and it can't be automatically changed.


The WiFi model plugs into the back of the 3M-50 on the side. Either side would probably work, but we chose the left side in this picture which happened to be radio 2.


The Marvell WiFi model is a USNAP type of plug. It is a standard type of connection that should fit a few different thermostats or other devices that use USNAP type of plugs.
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The 3M-50 thermostat has two covers that pop off of the top and bottom. The top has a sticker warning you to turn off the HVAC power before removing the old thermostat. If you've ever watched HVAC technicians, they rarely do this. We did it, just to be safe. You can see all the touch areas in this photo very well. A set of anchors and screws for mounting were located under the bottom panel.


The top panel contains the wire ports for various HVAC systems. Once you remove your old thermostat, make sure you label each wire BEFORE you unhook them. If you forget what was was hooked into what, you'll end of tracing the lines back to the HVAC system. There is no standard coloring for HVAC wiring.


A caveat about the 3M-50. The thermostat requires that the HVAC "C" wire is provided for power. Many installations don't bother running this power wire since the thermostats run off of battery power. If you don't have a "C" wire (we didn't), you'll end up running another line from the HVAC unit. If you can't do that, you can put a 12-24V transformer to the 3M-50 for power. Batteries alone will not be able to power the WiFi model. The thermostat will work with batteries alone, but you lose the WiFi function. Make sure you have power going to the thermostat.


After a few days of tracing wiring and running a new "C" wire, we had the 3M-50 up and running on HVAC power. Since the batteries are now only for backup, you'll probably never notice when they run out unless there is a power failure... but our batteries are already dieing in this image.

WiFi Setup


After correctly wiring the thermostat, you'll need a device that can connect to a WiFi network. This could be anything like a smart-phone or a laptop, but if you don't have a device, you won't be able to set the thermostat up. If you're reading this site, you'll be able to manually setup the thermostat. Once you connect to the thermostat wireless network, you navigate to the WiFi module by going to over HTTP. Once on the internal webserver, you can setup the thermostat for DHCP or a static address and the rest is fairly simple.


The network setup is easy enough to understand. You'll have to type everything in manually, the model won't scan networks for you. Even if it did, you should be hiding your SSID. The model supports 802.11i, so WPA2 will work fine with the thermostat.


After the wireless setup is completed, you'll be given a PIN and access code. The PIN is located on the thermostat on the top left (where the time would be). You need to go to http://www.radiothermostat.com/wifi/ and complete the setup from there.


Once everything is setup, you are given a web based control that mimics the thermostat display. You operate it the same way. It is a bit clunky, but it works.

One thing that we don't like is the privacy policy (pdf) of the Radio Thermostat website. Once you sign up, you're basically giving up your personal information for sale by the company. This includes your name, address, and even temperature status. This is a VERY huge problem for a system like this. Why should this random company be able to sell all my information? ASE Labs will not recommend use of this website for this very reason. Privacy is too important to lose on a thermostat.

There may be a saving grace, though. In Q1 of 2011, there will be an API released that will allow you to control the thermostat directly. Once this happens, we'll be happy to recommend the product without using the website. Your privacy is important, protect it.

While there may not be an API released, if you are handy with a packet sniffer, you can figure everything out on your own. We'll try to list what we've found from our inspection or from around the web. The thermostat uses JSON for data and it is RESTful. If you do a GET /tstat/info, you will get the current conditions of the thermostat (in JSON). You can change the URL of the "cloud" service the thermostat uses by going to the internal web server of the thermostat. We tried changing that to another computer, but we didn't capture any packets... We'll have to wait for the API for control.
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As a thermostat, the 3M-50 works great. It keeps the temperature fairly constant. It will have to drop a degree before turning the system on for heating or cooling. In addition, the large display is very nice for controlling the thermostat and the touch screen works great. You have a variety of different programming options for automatically setting the temperature. Since this is targeted to the WiFi crowd, we found the best way to use it is to turn it down when we left and back up on our way back. This is great for trips and such or extended stays. No longer will you need to worry about the thermostat. Another good feature of the 3M-50 is the electronic system switch. The thermostat can change from heating to cooling automatically. The Marvell provided WiFi module works great and once an API is released, you'll be much happier. Using the website is not something we want to do.


While this product was provided by Marvell to show off their WiFi module, we're reviewing the 3M-50 as a whole. The concept is excellent and the price is fine at $100. Being able to remotely control your thermostat is a welcome addition to the smart home. The current website for controlling the 3M-50 needs a privacy policy change, but we're on the tip of getting a true API released and once that happens, you'll be able to control the thermostat directly. This is where we want to be. Only then will we recommend the 3M-50. Technology should be easy, and we (the home owner) should be in control of our devices. Marvell's WiFi technology is great and it works well. Marvell makes so many support products and chips. You probably have a Marvell LAN controller or SATA controller in your computer.

ASE Labs would like to thank Marvell for providing this product for review.


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