No C-Wire Smart Thermostat Install | Emerson Sensi WiFi | Step by Step | Robert Shaw Replacement

[@ThraciusRex]

At 5:06 we can see that you've connected 5 wires with what looks like a brown wire connected to the C (common) slot. The blue wire is usually reserved for common and your old thermostat did not have the blue wire connected and only had 4 wires. What did you need to do and why did you end up connecting a C wire?

[@PoolarityChannel]

There was an extra wire that had voltage that I though might have been mislabelled but it did not work as the C wire. I ended up using Lithium AA batteries (see links in description) that gave lasted 3+ years and still has 5/5 bars full charge, which basically by my accounts is permanent power source for all practical purposes. So I didn't fuss around with a C wire for that reason

[@caweyskadalmar]

Thanks

[@TechCrazy]

Man you missed the need for batteries and C Wire topic which I believe lot of old thermostat owners are going to have to deal with. So I see there are batteries in there, so does it mean I don't need to bother with 'Common Wire" to power the device?

[@AshGreen359]

How do you know which wire is which if you just have no thermostat but 4 wires sticking out the wall? I have white with blue stripe White with red stripe Red and blue

[@panjavijit]

I too have 4 wires RC, G, Y, W. I did see you connected the respective points. Do we need the brown wire in C or it will work without that.

[@PoolarityChannel]

I use Lithium batteries in mine , and on 1 charge it will last more than a year.

[@mythos000000025]

Mine wont turn off, everything is setup just like yours, 4 wire, even the old panel the same but when I try to turn it off it just kicks on the fan. Problem is it turns on the heater to. Seems like it runs both ac and gas at the same time

[@qaswed854]

my old thermostat has a blue wire connected to the C, a black wire connected to W/E, red wire connected to RH and white wire connected to W2

[@billevans2400]

Why do I get the message that I need a C wire when comparing the wiring configuration between the new and old thermostats? Early in your video you comment that the old system had no C wire and had batteries and the new Sensi also has batteries and would not need the C wire. My old Robert Shaw unit had and O wire. The Sensi unit has an O terminal combined with another letter. Same is with the W terminal which also has another letter. I could not duplicate the same test you did when comparing the two wiring configurations. Yours were the same for both units and you had no C wire but indicated that you had a valid configuration. I did see that the wire to the G connection could be used at the C connection which would make the Fan mode only operate when the unit was either heating or cooling. By the way my unit is electric and is a heat pump. Thanks for any comments you might suggest.

[@twitter.comfixwifi992]

Without the C wire will the WiFi work? I have a 2 wire system and been checking if the built in jumper could be removed between RC and RH terminal? If it could I could connect a transformer to this thermostat on the RC and C terminal.

[@PoolarityChannel]

I use the Sensi without the C-wire, it requires 2 AA Batterys, so I use the Lithuim which so far has lasted 3+ years, WiFi and all. (see the description area for the ones I got). But no issues its been over 3 years.

[@monique85]

I have 2 wire system also and I purchased a 24 volt ac plug in transformer

[@eswords1]

@@PoolarityChannel hello I am very confused . When you take apart the old tstat you have no c wire attached but then at 5:08 there is suddenly a brown wire and it is attached to the sensi C wire lug?? I thought the whole point of this video was not needing the C wire? I ask this not just because of the confusion; but because is that then meaning your batteries are not being necessary (as you do indeed use a C wire ?) ,and so all bets are off for having wifi with no C wire and running the Wi-fi completely off batteries? I have no C wire for my ST55U model sensi smart thermostat but I Do get the flashing network icon in the upper left corner of the screen but it will not ever connect; and I have been troubleshooting this for hours now and cannot make the thing connect. I have R W Y G wires in the app setup. So my question is is your video representative of actually not having a C wire or not; And if you don't have a C wire can you get the wifi without the C wire or not? Thank you

[@PoolarityChannel]

@@eswords1 so sorry for the confusion this was many years ago, so from my recollection I was trying out multiple additional wires that was hiding behind the drywall. In fact there is absolutely no C-wire. I have been using 2 AA Energizer Lithium batteries for 5+ years to power this, and it has been absolutely great, have not yet changed batteries at all. The wifi is powered by the 2 AA batteries and have run flawlessly.

[@eswords1]

did you leave any wire attached to the C lug at all, and if so, is it possible that that is providing power for the wifi?

[@dbaranek]

Did you ever make a video for the Honeywell thermostat?

[@PoolarityChannel]

Never did, I got too busy. But I'm very happy with this Sensi Thermostat.

[@dbaranek]

@@PoolarityChannel Thank you!

[@ggjflyguy]

are you still using this thermostat and are you still happy with it? looking to change my thermostats, the one for my upstairs unit has no c wire and im considering this one.

[@PoolarityChannel]

Still using it, I use rechargeable AA lithium batteries on it, it's been 6+ months and the battery level.is still at 95%. I use the remote Wi-Fi feature a lot through my google home hub, hey google turn on the heat, increase temp...all by voice command

[@PoolarityChannel]

Those lithium AA batteries still at 95% after 2 yrs

[@lawrencelin9763]

Hi! Do you remember if your box came shrink wrapped or was it just the seal but no wrap outside? Thank you.

[@PoolarityChannel]

It was not shrink-wrapped

[@ralphmb8959]

I have a 2 wire system, oil heat only. The Sensi app says that wire configuration is not compatible with the Sensi thermostat. But you say it will work without a C wire using battery power only. Why wouldn’t the Sensi app say it would work? It doesn’t make sense to me. I don’t want to begin replacing my old thermostat until I’m sure. Please help.

[@PoolarityChannel]

I don't think this works with Oil Heat, I believe my brother had the same problem. Mine is Gas Furnance, and apparently it works with a Gas Furnance without a C wire, but not with the Oil Heat.

[@ignoranamus22]

I saw a blue wire wrapped around the other wires in your wall. Isn’t this your common wire?

[@ThraciusRex]

The blue wire would be the common. May not be connected to anything on the other end. Mine is like that. I'm wondering if that might be the reason why I can't get my Sensi to add into Homekit.

[@francoisnguyen6623]

You have an unused C wire in your wire bundle. You should use that to power the thermostat

[@nlcwilson2017]

Hi Poolarity, I was wondering how the wires came out of your Robertshaw. Did you have to cut them?

[@PoolarityChannel]

No need to ut, you unscrew the screws behind the wires and then they just pull out. If you see the 5 round holes above the wires at 2:30, in those round holes is a flat screw, just unscrew that screw in the holes and the wires will come out

[@nlcwilson2017]

@@PoolarityChannel than you so much!

[@soufianemess7681]

A quick question about the C wire if anyone has the answer. Yes this thermostat works also without C wire (then must be powered by batteries) but does it mean that if powered with batteries you won't benefit from the Wi-Fi features? Because I just bought the same and I didn't install it yet, just playing with it (batteries plugged in). When turning on the Wi-Fi feature, I can see an X at top left rather than the Wi-Fi logo. I was wondering if the C wire is really required for not only powering it more efficiently than with batteries (you won't have to worry about changing batteries) but C wire would also be required for full Wi-Fi features?

[@PoolarityChannel]

Use it with AA Energizer lithium batteries, been lasting 4+ years without changing. WiFi works well, you need to program it in the app

[@soufianemess7681]

@@PoolarityChannel Thx for the tips man! I'll hope that once i connect the C wire, i'll be able to use the wifi Features. I'm suspecting that this thermostat needs the C wire absolutely for the Wifi features, otherwise with batteries, it would just run as a normal thermostat

[@Cello69.]

My furnace only has 2 wires. Will it still work you think?

[@PoolarityChannel]

Download the instructions to check that

[@1232bluejays]

How long do the batteries last with no c wire?

[@PoolarityChannel]

Using lithium AA batteries, 4+ yrs, I use rechargeable lithium batteries in the links in description area, those last 4+ yrs on one charge

[@michaelvaughan9157]

You never removed the wires from the old one